Neutrality remake batch: from-scratch field derivation with project parameters and derived fields
---
title: Wood Flooring
category: Architectural / Finishes
−toc_depth: 3
description: >
− When to use: Interior wood finish flooring in commercial and institutional projects — solid strip and plank, engineered multi-ply strip and plank, wood parquet tile and block, and end-grain industrial block. Covers species and grade selection, moisture management and acclimation, subfloor preparation over wood and concrete substrates, nail/staple-down, glue-down, and floating attachment methods, adhesives and fasteners, factory-prefinished and site-applied finishes, gymnasium maple sports floors, and maintenance provisions.
− Not intended for: Resilient wood-look flooring such as luxury vinyl plank, VCT, and linoleum (see [[sync/resilient-flooring]]); carpet and carpet tile (see [[sync/carpet]]); ceramic, porcelain, and stone tile (see [[sync/ceramic-tile]]); polished, ground, or sealed bare concrete floors (see [[sync/polished-concrete]]); poured and precast terrazzo (see [[sync/terrazzo]]); structural wood subfloor sheathing, joists, and framing (IBC Chapter 23 and the structural drawings); and bamboo, cork, and access/raised flooring, which fall outside NWFA/NOFMA grading and this standard.
+ When to use: Interior wood finish flooring — solid sawn strip and plank, engineered multi-ply flooring, parquet tile and block, end-grain block, and maple sports flooring — installed over wood framing, wood panel subfloors, and concrete slabs above, on, and below grade. Covers construction, species, cut, grade, and dimension selection; in-service interior climate and acclimation criteria; concrete and wood substrate moisture testing and moisture control; nail-down, staple-down, adhesive, and floating attachment; factory-applied and site-applied finish systems; expansion provisions; fire and emissions requirements; and field verification, maintenance, and warranty provisions.
+ Not intended for: Resilient wood-look flooring including luxury vinyl plank, vinyl composition tile, and linoleum (see [[sync/resilient-flooring]]); carpet and carpet tile (see [[sync/carpet]]); ceramic and porcelain tile (see [[sync/ceramic-tile]]); natural stone tile (see [[sync/natural-stone-tile]]); polished, ground, or sealed bare concrete (see [[sync/polished-concrete]]); poured and precast terrazzo (see [[sync/terrazzo]]); resinous and epoxy floor coatings (see [[sync/resinous-flooring]] and [[sync/epoxy-flooring]]); walk-off and entrance flooring (see [[sync/entrance-flooring]]); raised access floor systems (see [[sync/raised-access-flooring]]); structural framing, sheathing, and subfloor panels (see [[sync/wood-framing]] and [[sync/wood-sheathing]]); wood base, shoe, and running trim (see [[sync/architectural-wood-trim-and-paneling]]); and bamboo, cork, and laminate flooring, which are not graded under the wood flooring rules referenced here.
---
# Scope {toc}
−## This standard governs the materials and installation of interior wood finish flooring — solid strip and plank, engineered multi-ply flooring, wood parquet tile and block, and end-grain block — installed over wood and concrete substrates in commercial and institutional construction. {note}
−## Wood flooring is specified where the appearance, warmth, resilience, or sports performance of a real wood surface is required: corridors, offices, classrooms, lobbies, gymnasiums and multipurpose rooms, residential units within commercial projects, and specialty commercial spaces. {note}
−## Unlike a manufactured floor covering laid down as a finished sheet, a wood floor is a hygroscopic natural material that gains and loses moisture with its surroundings and changes dimension as it does; its long-term performance is inseparable from the moisture condition of the substrate, the acclimation of the wood, and the building's ability to hold a stable interior climate. {note}
+## This standard governs interior wood finish flooring together with the substrate preparation, moisture control, attachment, and finish work that make it perform. {note}
+## A wood floor is an assembly rather than a covering. The prepared substrate, the moisture control layer, the attachment medium, the wood itself, the finish, and the perimeter expansion provisions each carry part of the performance, and a defect in any one of them surfaces as a defect in the floor. {note}
+## Wood is hygroscopic: it exchanges moisture with the air and the substrate around it until it reaches equilibrium, and it changes dimension as it does. That single property is why the moisture condition of the substrate, the moisture content of the wood at the moment it is installed, and the interior climate the building can actually hold in service govern this standard more than any appearance or hardness property. {note}
+## The product families within this scope are the following: {note}
−## A wood floor is a system of substrate, attachment, wood, and finish, not a single product. {note}
−## It consists of the prepared and tested subfloor, any required vapor retarder or sleeper assembly, the attachment medium (fasteners or adhesive), the wood flooring itself, and the finish — factory-applied or field-applied — together with perimeter expansion provisions, transitions, and the maintenance regime that preserves it. {note}
+- Solid sawn flooring milled from a single piece of hardwood or softwood, in strip, plank, and mixed-width formats
+- Engineered flooring built from a hardwood face over a cross-laminated plywood, high-density fiberboard, or edge-glued lumber core
+- Parquet tile and block, including finger block, herringbone, chevron, and patterned assemblies
+- End-grain block set with the grain vertical as an industrial or specialty wearing surface
+- Northern hard maple sports flooring installed over an engineered resilient subfloor assembly
−## The Contractor shall verify that the wood flooring, the adhesive or fasteners, and the moisture-control measures are compatible with the measured substrate condition and with one another.
−## The Contractor shall not begin installation until the substrate, the ambient conditions, and the wood have met the moisture and acclimation acceptance criteria of this standard.
−## Coordinate the concrete slab, its curing method, and its under-slab vapor retarder with [[sync/cast-in-place-concrete]] and [[sync/concrete-curing-and-finishing]].
−## Coordinate transitions and finish-floor elevations with adjacent finishes specified under [[sync/resilient-flooring]], [[sync/carpet]], [[sync/ceramic-tile]], [[sync/polished-concrete]], and [[sync/terrazzo]].
−## The species, grade, dimensions, attachment method, and finish are selected together for the service the floor must survive — a wide solid plank that performs in a stable, conditioned residence will cup and gap in a high-traffic lobby with swinging humidity, where a narrow engineered product is required. {note}
−## The dominant causes of wood flooring failure are moisture-related — installation over a wet or untested slab, installation of wood that was not acclimated to its in-service moisture content, and operation of the building outside the humidity band the floor was specified for; all three are preventable and all three are controlled before and during installation, not after. {note}
+## The following are outside this standard: {note}
+- Resilient wood-look flooring, including luxury vinyl plank, vinyl composition tile, and linoleum, specified under [[sync/resilient-flooring]]
+- Carpet and carpet tile, specified under [[sync/carpet]]
+- Ceramic, porcelain, and natural stone tile, specified under [[sync/ceramic-tile]] and [[sync/natural-stone-tile]]
+- Polished, ground, and sealed bare concrete, specified under [[sync/polished-concrete]]
+- Poured and precast terrazzo, specified under [[sync/terrazzo]]
+- Resinous and epoxy floor coatings, specified under [[sync/resinous-flooring]] and [[sync/epoxy-flooring]]
+- Walk-off matting and entrance flooring, specified under [[sync/entrance-flooring]]
+- Raised access floor systems, specified under [[sync/raised-access-flooring]]
+- Structural framing, sheathing, and subfloor panels, specified under [[sync/wood-framing]] and [[sync/wood-sheathing]]
+- Wood base, shoe, thresholds, and running trim, specified under [[sync/architectural-wood-trim-and-paneling]]
+- Bamboo, cork, and laminate flooring, which are manufactured under product rules other than the wood flooring grading rules referenced here
+
+## The Contractor shall verify that the flooring, the attachment medium, the moisture control measure, and the measured substrate condition are compatible with one another before flooring material is ordered.
+## The Contractor shall not begin installation until the substrate condition, the interior ambient conditions, and the moisture content of the wood all satisfy the acceptance criteria of this standard.
+## The concrete substrate, its curing and sealing method, and its under-slab vapor retarder shall be as specified in [[sync/cast-in-place-concrete]], [[sync/concrete-curing-and-finishing]], [[sync/slab-on-grade]], and [[sync/vapor-barriers-under-slab]].
+## Patching and leveling of the substrate shall use products specified in [[sync/cementitious-self-leveling-underlayment]] and approved in writing by the flooring and adhesive manufacturers.
+## Finish floor elevations and transitions at every boundary between wood flooring and an adjacent floor finish shall be as detailed on [[drawing: the interior finish details]].
+## Curing compounds, sealers, and bond breakers left on a slab are a frequent cause of adhesive bond failure, which is why the curing method is coordinated with this standard rather than left to the concrete trade alone. {note}
+
# Referenced Standards {toc}
| Standard | Title |
|----------|-------|
−| NWFA Installation Guidelines | Wood Flooring Installation Guidelines (2025 revision) |
−| NWFA/NOFMA Unfinished | Grading and Manufacturing Standards for Unfinished Solid Wood Flooring (2018 revision) |
−| NWFA/NOFMA Factory Finished | Grading and Manufacturing Standards for Factory Finished Solid Wood Flooring (2019 revision) |
−| ANSI/HPVA EF 2020 | American National Standard for Engineered Wood Flooring (Decorative Hardwoods Association) |
−| MFMA Grading Rules | Maple Flooring Manufacturers Association Grading Rules for Northern Hard Maple, Beech, and Birch |
+| NWFA Installation Guidelines | Wood Flooring Installation Guidelines |
+| NWFA Sand and Finish Guidelines | Wood Flooring Sand and Finish Guidelines |
+| NWFA/NOFMA Unfinished | Grading and Manufacturing Standards for Unfinished Solid Wood Flooring |
+| NWFA/NOFMA Factory Finished | Grading and Manufacturing Standards for Factory Finished Solid Wood Flooring |
+| ANSI/HPVA EF | American National Standard for Engineered Wood Flooring |
+| MFMA Grading Rules | Grading Rules for Northern Hard Maple, Beech, and Birch Flooring |
+| ASTM D2047 | Test Method for Static Coefficient of Friction of Polish-Coated Flooring Surfaces as Measured by the James Machine |
| ASTM D2394 | Test Methods for Simulated Service Testing of Wood and Wood-Based Finish Flooring |
+| ASTM D4442 | Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials |
+| ASTM E648 | Test Method for Critical Radiant Flux of Floor-Covering Systems Using a Radiant Heat Energy Source |
+| ASTM E1007 | Test Method for Field Measurement of Tapping Machine Impact Sound Transmission Through Floor-Ceiling Assemblies |
+| ASTM E2179 | Test Method for Laboratory Measurement of the Effectiveness of Floor Coverings in Reducing Impact Sound Transmission Through Concrete Floors |
+| ASTM E492 | Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using the Tapping Machine |
+| ASTM F710 | Practice for Preparing Concrete Floors to Receive Resilient Flooring |
| ASTM F1667 | Specification for Driven Fasteners: Nails, Spikes, and Staples |
| ASTM F1869 | Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride |
| ASTM F2170 | Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes |
−| ASTM F2772 | Standard Specification for Athletic Performance Properties of Indoor Sports Floor Systems |
−| IBC | International Building Code, Chapter 23 — Wood (current adopted edition) |
+| ASTM F2659 | Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement and Anhydrite Floor Slabs Using a Non-Destructive Electronic Moisture Meter |
+| ASTM F2772 | Specification for Athletic Performance Properties of Indoor Sports Floor Systems |
+| NFPA 253 | Test Method for Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat Energy Source |
+| CDPH Standard Method v1.2 | Method for the Testing and Evaluation of Volatile Organic Chemical Emissions from Indoor Sources Using Environmental Chambers |
+| SCAQMD Rule 1168 | Adhesive and Sealant Applications (volatile organic compound content limits) |
+| SCAQMD Rule 1113 | Architectural Coatings (volatile organic compound content limits) |
+| 40 CFR Part 770 | Formaldehyde Standards for Composite Wood Products (TSCA Title VI) |
+| IBC | International Building Code, Chapters 8, 12, and 23 |
−## All materials, testing, and installation shall comply with the latest edition adopted by the Authority Having Jurisdiction for each of the standards listed, unless a specific edition is cited.
−## Where the contract documents, a referenced standard, or the flooring manufacturer's written instructions impose a more stringent requirement than the minimum of any other standard, the more stringent requirement governs unless the Architect of Record directs otherwise in writing.
−## The Contractor shall follow the manufacturer's written installation instructions in addition to this standard.
−## As with all field-installed wood finishes, the manufacturer's written installation instructions define the conditions under which the product warranty is valid; an installation that departs from them — wrong adhesive, wrong fastener, wrong substrate, or wrong moisture condition — voids the warranty regardless of workmanship quality. {note}
−## The NWFA Installation Guidelines are the de facto industry installation reference, universally accepted by manufacturers; the NWFA/NOFMA standards define the grade of unfinished and factory-finished solid hardwood; ANSI/HPVA EF 2020 is the governing product standard for engineered wood specifically, defining veneer thickness, the three-cycle-soak bond-line delamination test, moisture content, and machining tolerances; and the MFMA rules together with ASTM F2772 govern the specialty case of maple gymnasium sports floors. {note}
+## Materials, testing, and installation shall comply with the latest edition of each standard listed above as adopted by the Authority Having Jurisdiction, unless a specific edition is cited.
+## Where a referenced standard, the Contract Documents, and the flooring manufacturer's written installation instructions impose differing requirements, the more stringent requirement shall govern unless the Architect of Record directs otherwise in writing.
+## The Contractor shall install the flooring in accordance with the flooring manufacturer's written installation instructions in addition to this standard.
+## A manufacturer's written installation instructions define the substrate, moisture, ambient, adhesive, and fastener conditions under which its product warranty remains valid, which is why they are enforceable alongside the consensus standards rather than subordinate to them. {note}
+## The reference set divides along product lines: the NWFA guidelines are the industry installation reference for every wood flooring type; the NWFA/NOFMA rules define the grade of solid hardwood; ANSI/HPVA EF defines veneer thickness, core construction, moisture content, machining tolerance, and the three-cycle-soak delamination test for engineered flooring; and the MFMA rules together with ASTM F2772 govern northern hard maple sports flooring. {note}
# Submittals {toc}
## Action Submittals {toc}
−### The Contractor shall submit the following for the Architect's review prior to procurement and installation:
+### The Contractor shall submit the following for the Architect of Record's review before flooring material is ordered:
−- Product data for the wood flooring, identifying species (by botanical name where ambiguous), grade and the governing grading standard, nominal thickness and face width, edge and end profile, wear-layer (veneer) thickness for engineered products, factory finish or unfinished, and the manufacturer's written installation instructions
−- Product data for the adhesive, fasteners, vapor retarder, underlayment, sound-control mat, and any moisture-mitigation or sleeper components, demonstrating compatibility with the wood flooring and the substrate
−- Substrate moisture test reports for the actual subfloor — wood moisture content for wood subfloors, and ASTM F2170 in-situ relative humidity (and ASTM F1869 emission rate where used) for concrete slabs — identifying test locations, ambient conditions, and dates
−- Samples of the wood flooring showing the specified species, grade, surface texture, finish, and the natural range of color and grain to be expected
−- For site-finished work, samples of the finished floor showing the specified stain color, finish type, and sheen
−- For gymnasium maple sports floors, MFMA grade certification, the floor-system performance class, and ASTM F2772 performance test data for the proposed system
−- Maintenance instructions identifying approved cleaning agents and the recoat or refinish compatibility of the delivered finish
+- Product data for the wood flooring, identifying construction, species and botanical name, governing grading rule and grade, sawing method, nominal thickness, face width, length distribution, joinery, edge profile, surface texture, wear layer thickness for engineered products, and factory finish
+- The flooring manufacturer's written installation instructions, including the substrate, moisture, ambient, and attachment limits under which the product warranty remains valid
+- Product data for the adhesive, fasteners, vapor retarder and moisture control membrane, acoustical underlayment, sleeper and panel subfloor components, patching and leveling compounds, and transition profiles
+- Not fewer than three samples of the flooring, each at least 12 in long, showing the range of color, grain, and character marks within the specified species and grade
+- Samples of the site-applied finish system on the specified species and grade, showing the sealer, stain color, finish, and sheen
+- Shop drawings for pattern floors, borders, feature strips, sleeper and panel assemblies, expansion breaks, and transitions
+- MFMA grade certification, system component data, and ASTM F2772 test results for the proposed sports floor assembly
+- Documentation of formaldehyde emission compliance under 40 CFR Part 770 for flooring containing a composite wood core
+- Documentation of low-emitting materials compliance and volatile organic compound content for the flooring, adhesive, underlayment, and finish
```datasheet
label: Action Submittals Required
type: checkbox
options:
− - "Product data — wood flooring (species, grade, dimensions, profile, finish)"
− - "Product data — adhesive, fasteners, vapor retarder, underlayment, sound mat"
− - "Substrate moisture test reports (wood MC; F2170 / F1869 for concrete)"
− - "Samples — species, grade, texture, finish, color/grain range"
− - "Site-finish samples (stain color, finish type, sheen)"
− - "Gymnasium: MFMA certification + ASTM F2772 performance data"
− - "Maintenance instructions (cleaning + recoat compatibility)"
−default: "Substrate moisture test reports (wood MC; F2170 / F1869 for concrete)"
+ - "Product data — wood flooring, construction, species, grade, dimensions, profile, finish"
+ - "Manufacturer's written installation instructions"
+ - "Product data — adhesive, fasteners, vapor retarder, underlayment, subfloor components, transitions"
+ - "Samples — species, grade, color and grain range"
+ - "Samples — site-applied finish system, stain color, sheen"
+ - "Shop drawings — patterns, borders, sleeper assemblies, expansion breaks, transitions"
+ - "Sports floor — MFMA certification and ASTM F2772 test results"
+ - "Formaldehyde emission compliance under 40 CFR Part 770"
+ - "Low-emitting materials and volatile organic compound documentation"
```
−### Installation shall not begin until the substrate moisture test reports have been submitted and reviewed.
−### The substrate moisture condition determines whether the specified product and attachment method are appropriate at all, and whether a moisture-mitigation measure is required; it is the gating submittal. {note}
+### Wood is a natural material whose color and grain vary within any grade, and a single sample cannot represent that variation; the multiple-sample requirement exists so the accepted range is established before the floor is manufactured rather than argued after it is laid. {note}
+## Informational Submittals {toc}
+
+### The Contractor shall submit the following before installation begins:
+
+- Substrate moisture test reports identifying the test method, the number and location of tests, the ambient conditions, the date, and the technician, covering ASTM F2170 internal relative humidity for concrete and ASTM D4442 or calibrated meter readings for wood
+- Slab surface pH test results and the surface preparation report required by ASTM F710
+- The acclimation record, including delivery date, storage location, stacking method, daily interior temperature and relative humidity, and dated moisture content readings of the flooring and the substrate
+- Qualification data for the installing firm and the on-site foreman, listing comparable completed projects with contact references
+- The pre-installation conference report, listing attendees, decisions, and unresolved items
+- Certification that the moisture control measure installed is rated for the substrate condition actually measured
+
+```datasheet
+label: Informational Submittals Required
+type: checkbox
+options:
+ - "Substrate moisture test reports — ASTM F2170 for concrete, ASTM D4442 or calibrated meter for wood"
+ - "Slab surface pH and ASTM F710 preparation report"
+ - "Acclimation record with dated moisture content and ambient readings"
+ - "Installer qualification data with comparable project references"
+ - "Pre-installation conference report"
+ - "Certification that the moisture control measure matches the measured substrate condition"
+```
+
+### Installation shall not begin until the substrate moisture test reports have been submitted and reviewed by the Architect of Record.
+### The substrate moisture reports are the gating submittal because they determine whether the specified product, attachment method, and adhesive are usable at all, and whether a moisture control measure has to be added to the assembly before any flooring is ordered. {note}
+
## Closeout Submittals {toc}
−### The Contractor shall provide the following at project closeout:
+### The Contractor shall submit the following at Substantial Completion:
−- Manufacturer product warranty documentation executed in the Owner's name
−- Record of the final substrate moisture test results, the wood moisture content at installation, the acclimation period and conditions, and the attachment method and adhesive or fastener actually used, retained for warranty purposes
−- For gymnasium sports floors, the ASTM F2772 field or certified performance test results and the game-line layout record
−- Maintenance materials transmittal documenting attic stock, touch-up, and finish material delivered to the Owner
+- Manufacturer product warranty and, for factory-finished flooring, finish wear-through warranty, executed in the Owner's name
+- The Contractor's written installation workmanship warranty
+- The complete moisture record, comprising final substrate readings, wood moisture content at installation, the acclimation period and conditions, the attachment method used, and adhesive or fastener product and lot identification
+- Maintenance data identifying approved cleaning agents and methods, the recoat and refinish procedure with the compatible finish product, and the interior temperature and relative humidity range the floor must be held within
+- ASTM F2772 field verification results and the as-installed game line record for sports flooring
+- Transmittal for the attic stock, touch-up, and finish material delivered to the Owner
```datasheet
label: Closeout Submittals Required
type: checkbox
options:
− - "Manufacturer product warranty (executed in Owner's name)"
− - "Record of substrate moisture, wood MC, acclimation, attachment method"
− - "Gymnasium: ASTM F2772 performance results + game-line layout record"
− - "Maintenance materials transmittal (attic stock, touch-up, finish)"
−default: "Manufacturer product warranty (executed in Owner's name)"
+ - "Manufacturer product and finish warranties executed in the Owner's name"
+ - "Contractor installation workmanship warranty"
+ - "Complete moisture, acclimation, and attachment record"
+ - "Maintenance data — cleaning, recoat procedure, humidity range"
+ - "Sports floor — ASTM F2772 field results and game line record"
+ - "Attic stock and touch-up material transmittal"
```
+### The moisture record is the document a manufacturer asks for first when a claim is filed, and it cannot be reconstructed after the floor is down; assembling it is a closeout deliverable only because the readings themselves were taken during the work. {note}
+
# Quality Assurance {toc}
## Installer Qualifications {toc}
+### The installing firm shall hold the qualification indicated in the datasheet.
+
```datasheet
label: Installer Qualification
−type: radio
+type: select
options:
− - "NWFA Certified Installer (or manufacturer-certified for the specified system)"
− - "Experienced commercial wood flooring installer (documented comparable projects)"
− - "MFMA / sports-floor certified installer (gymnasium maple systems)"
−default: "Experienced commercial wood flooring installer (documented comparable projects)"
+ - "Installer with documented experience on comparable commercial wood flooring projects"
+ - "NWFA Certified Installer"
+ - "NWFA Certified Sand and Finisher"
+ - "Installer certified in writing by the flooring manufacturer for the specified system"
+ - "MFMA accredited sports floor contractor"
+default: "Installer with documented experience on comparable commercial wood flooring projects"
```
−### Wood flooring shall be installed by an installer with documented experience installing the specified product type, attachment method, and finish on commercial projects of comparable size and complexity.
−### Gymnasium maple sports floors shall be installed by an installer certified or approved by the sports-floor system manufacturer.
−### A wood floor is fitted, fastened or bonded, and on site-finished work sanded and finished by hand, and the cured result reflects the installer's judgment about acclimation, fastening schedule, expansion gaps, and moisture readings that cannot be inspected or corrected after the floor is down and finished. {note}
+### The installing firm shall assign a single on-site foreman who is present for the duration of the flooring work.
+### Where the Contract Documents require a certified installer and the certification lapses during the work, the Contractor shall notify the Architect of Record in writing within five business days and shall propose a replacement firm holding the required certification.
+### A wood floor is fitted, fastened or bonded, and on site-finished work sanded and coated by hand, and the finished result records the installer's judgment about acclimation, fastening schedule, expansion allowance, and moisture readings — judgments that cannot be inspected or corrected once the floor is down and coated. {note}
## Mock-Up {toc}
+### The requirement for a mock-up shall be as indicated in the datasheet.
+
```datasheet
label: Mock-Up Required
type: radio
options:
− - "Yes — install a representative area including a transition and, for site-finish, the finish system"
− - "No"
−default: "No"
+ - "Mock-up required"
+ - "Mock-up not required"
+default: "Mock-up not required"
```
−### Where a mock-up is required, the Contractor shall install a representative area of the complete floor at a location directed by the Architect, including a perimeter expansion detail and a transition to an adjacent finish, and for site-finished work the full sealer, stain, and finish system.
−### The mock-up shall remain available for comparison throughout the work and shall establish the acceptable standard for color and grain range, surface texture, stain color, sheen, and joint tightness.
−### Wood is a natural material with an inherent color and grain range within any grade; the mock-up sets the Owner's and Architect's expectation for that range so that natural variation is not later rejected as a defect. {note}
+### Where a mock-up is required, the Contractor shall install a representative area of the complete floor assembly at a location directed by the Architect of Record.
+### The mock-up shall include a perimeter expansion detail, a transition to an adjacent floor finish, and, for site-finished work, the complete sealer, stain, and finish system.
+### The mock-up shall be reviewed and accepted in writing by the Architect of Record before the balance of the flooring work begins.
+### The accepted mock-up shall establish the standard for color and grain range, character mark frequency, surface texture, stain color, sheen, and joint tightness for the remainder of the work.
+### The mock-up shall remain in place and undisturbed until the flooring work is accepted.
+### Where the parties disagree whether installed flooring matches the accepted mock-up, the Architect of Record shall make the initial determination.
+### Setting the acceptable range before production protects both parties: the Owner gets a floor that matches an object rather than a description, and the Contractor gets a defense against natural variation being rejected later as a defect. {note}
## Pre-Installation Conference {toc}
−### Before installation begins, the Contractor shall hold a pre-installation conference with the Architect, the flooring installer, the concrete or framing subcontractor, and the mechanical contractor responsible for building conditioning, to review the moisture test results, the acclimation plan, the HVAC startup sequence, the substrate preparation and flatness, the attachment method, the expansion provisions, the finish schedule, and the protection plan.
−### The HVAC shall be operational and the interior climate stabilized to the in-service range before the wood is delivered, acclimated, and installed.
−### The single most consequential coordination item is building conditioning; the conference exists to confirm that the mechanical and finishes schedules support that sequence rather than collide with it. {note}
+### The Contractor shall convene a pre-installation conference not less than ten business days before flooring is delivered to the site.
+### The conference shall be attended by the Architect of Record, the flooring installer, the concrete or framing subcontractor responsible for the substrate, and the mechanical contractor responsible for building conditioning.
+### The conference shall review the substrate moisture test results, the surface preparation and flatness, the moisture control measure, the acclimation plan, the mechanical system startup sequence, the attachment method, the expansion provisions, the finish schedule and sequence, and the protection plan.
+### The Contractor shall record the conference and distribute the report to all attendees within five business days.
+### Building conditioning is the coordination item that most often decides whether a wood floor succeeds, and the conference exists to confirm that the mechanical and finishes schedules support the sequence the flooring needs rather than collide with it. {note}
−# Acclimation and Service Conditions {toc}
+# Interior Climate and Acclimation {toc}
−## Building Conditioning Before Installation {toc}
+## In-Service Interior Climate {toc}
−### The permanent HVAC system shall be operational and the interior temperature and relative humidity stabilized to the expected in-service range before wood flooring is delivered to the project, throughout acclimation and installation, and continuously thereafter.
+### The permanent heating, ventilating, and air conditioning system shall be operating and the interior temperature and relative humidity stabilized within the ranges indicated in the datasheet before wood flooring is delivered to the site.
```datasheet
−label: Ambient Conditions for Acclimation and Installation
+label: In-Service Interior Temperature
type: range
unit: °F
−options:
− min: 60
− max: 80
− step: 5
+min: 55
+max: 85
+step: 1
+setpoints: [55, 60, 65, 70, 75, 80, 85]
default: 70
```
```datasheet
−label: Interior Relative Humidity Band (in service and during installation)
+label: In-Service Interior Relative Humidity, Minimum
type: range
−unit: "% RH"
−options:
− min: 30
− max: 55
− step: 5
−setpoints: [30, 35, 40, 45, 50, 55]
−default: 45
+unit: '% RH'
+min: 15
+max: 45
+step: 1
+setpoints: [15, 20, 25, 30, 35, 40, 45]
+default: 30
```
−### The interior shall be maintained between 60 °F and 80 °F and within a relative humidity band of approximately 35% to 55% during acclimation and installation, and the building shall be operated to hold that band in service.
−### Wood reaches an equilibrium moisture content set by the surrounding temperature and humidity; if the floor is installed into a dry, unconditioned shell and the building is later humidified, the boards swell and buckle, and if installed into a humid shell that is later dried, they shrink and gap. Stabilizing the climate before installation is what makes the wood's installed moisture content match its in-service moisture content. {note}
+```datasheet
+label: In-Service Interior Relative Humidity, Maximum
+type: range
+unit: '% RH'
+min: 40
+max: 70
+step: 1
+setpoints: [40, 45, 50, 55, 60, 65, 70]
+default: 50
+```
+### The specified temperature and relative humidity ranges shall be maintained continuously from the date of delivery through acclimation, installation, finishing, and Owner occupancy.
+### The Contractor shall record interior temperature and relative humidity at least once daily from the date of delivery until the flooring work is accepted, and shall include the log in the acclimation record.
+### The specified in-service relative humidity range shall be one the building's mechanical systems can hold year round for [[parameter: climate-zone]].
+### Where the mechanical systems cannot hold the specified range year round for [[parameter: climate-zone]] without supplemental humidification or dehumidification, the Contractor shall report the condition to the Architect of Record in writing before flooring is ordered.
+### Wood equilibrates to the temperature and relative humidity around it, and the equilibrium moisture content it reaches is what sets its installed dimension. A floor installed into a dry unconditioned shell that is later humidified swells and buckles; a floor installed into a humid shell that is later dried shrinks and gaps. Stabilizing the climate first is what makes the installed moisture content and the in-service moisture content the same number. {note}
+### The width of the specified humidity range matters as much as its center. A floor held between 30% and 50% relative humidity moves across a narrow band all year; the same floor allowed to swing between 15% and 70% moves several times as much, and the construction, face width, and cut have to be chosen for that swing. {note}
+
## Wood Acclimation {toc}
+### Wood flooring shall be acclimated on the conditioned site until its moisture content is in equilibrium with the specified in-service interior climate and within the differential limit of this standard relative to the substrate.
+
```datasheet
−label: Acclimation Period Before Installation
−type: select
+label: Minimum Acclimation Period
+type: range
unit: days
−options:
− - "3-5 days (engineered, stable jobsite conditions)"
− - "5-7 days (engineered or solid, typical)"
− - "7-14 days (solid, wide plank, or large moisture differential)"
− - "Until wood MC is verified within tolerance of subfloor MC (no fixed period)"
−default: "Until wood MC is verified within tolerance of subfloor MC (no fixed period)"
+min: 0
+max: 21
+step: 1
+setpoints: [0, 3, 5, 7, 10, 14, 21]
```
−### Wood flooring shall be acclimated on the conditioned jobsite until its moisture content reaches equilibrium with the in-service environment and is within the tolerance of this standard relative to the subfloor.
−### Acclimation shall be verified by moisture meter readings of the flooring and the subfloor, not by elapsed time alone.
−### Flooring shall be broken out of its packaging or cross-stacked with spacers as the manufacturer directs so that air can reach all surfaces during acclimation.
−### A fixed number of days is a planning estimate, not an acceptance criterion: the floor is acclimated when its measured moisture content is in equilibrium with the conditioned space, which depends on species, thickness, board width, and how far the delivered wood was from equilibrium. Wide and thick solid boards take longest; engineered products, being dimensionally more stable, take least. {note}
+### Acclimation shall be verified by moisture meter readings of the flooring and the substrate, and elapsed time alone shall not be accepted as evidence of acclimation.
+### Flooring shall be opened, cross-stacked with spacers, or otherwise broken out as the flooring manufacturer directs so that air reaches all faces of the material during acclimation.
+### The Contractor shall take and record moisture content readings at not fewer than five locations distributed across each flooring lot, and at a matching number of substrate locations.
+### A stated acclimation period is a scheduling allowance, not an acceptance criterion. How long a lot takes depends on species, thickness, face width, packaging, and how far the delivered material sits from equilibrium; wide, thick solid boards take longest, and engineered products designed for immediate installation may need none at all, which is why the specified minimum starts at zero. {note}
+### Acclimating material inside sealed packaging accomplishes nothing, because the wrap is what stops the exchange the process depends on. {note}
−## Wood and Subfloor Moisture Content {toc}
+## Wood Moisture Content at Installation {toc}
+### The moisture content of the flooring at the time of installation shall be within the range indicated in the datasheet.
+
```datasheet
−label: Solid Wood Flooring Moisture Content at Installation
+label: Flooring Moisture Content at Installation, Minimum
type: range
−unit: "%"
−options:
− min: 6
− max: 9
− step: 0.5
−setpoints: [6, 7, 8, 9]
−default: 8
+unit: '%'
+derived: "the equilibrium moisture content corresponding to the specified in-service interior temperature and relative humidity"
+min: 4
+max: 11
+step: 0.5
+setpoints: [4, 5, 6, 7, 8, 9, 10, 11]
```
```datasheet
−label: Maximum Wood Subfloor Moisture Content
+label: Flooring Moisture Content at Installation, Maximum
type: range
−unit: "%"
−options:
− min: 10
− max: 12
− step: 1
−setpoints: [10, 12]
−default: 12
+unit: '%'
+derived: "the equilibrium moisture content corresponding to the specified in-service interior temperature and relative humidity"
+min: 6
+max: 14
+step: 0.5
+setpoints: [6, 7, 8, 9, 10, 11, 12, 13, 14]
```
```datasheet
−label: Maximum Wood-Floor-to-Subfloor Moisture Differential
+label: Maximum Flooring-to-Substrate Moisture Content Differential
type: range
−unit: "percentage points"
−options:
− min: 2
− max: 4
− step: 1
−setpoints: [2, 4]
−default: 2
+unit: percentage points
+derived: "the specified face width, per the differential limits of the NWFA Installation Guidelines"
+min: 1
+max: 5
+step: 1
+setpoints: [1, 2, 3, 4, 5]
```
−### Solid wood flooring shall be installed at a moisture content between 6% and 9% per the NWFA Installation Guidelines, and engineered flooring at the moisture content stated by its manufacturer under ANSI/HPVA EF 2020, generally also 6% to 9%.
−### The wood subfloor moisture content shall not exceed 12%.
−### The moisture content differential between solid strip flooring and the wood subfloor shall not exceed 2 percentage points, and for plank 3 inches and wider shall not exceed 2 percentage points unless the manufacturer permits otherwise.
−### The Contractor shall measure and record the moisture content of both the flooring and the subfloor at multiple representative locations before installation.
−### A large moisture differential between the floor and the subfloor guarantees movement after installation as the two equalize: a floor drier than its subfloor will absorb moisture and cup or buckle, and a floor wetter than its subfloor will release moisture and gap. The differential limit, not the absolute reading alone, is what protects against post-installation movement. {note}
+### The moisture content differential between solid strip flooring narrower than 3 in and the wood substrate shall not exceed 4 percentage points.
+### The moisture content differential between solid flooring 3 in and wider and the wood substrate shall not exceed 2 percentage points.
+### The Contractor shall measure moisture content with a meter calibrated for the specific gravity of the species being measured, and shall record the species correction applied.
+### Equilibrium moisture content is a function of the surrounding temperature and relative humidity, so a range appropriate to a conditioned interior held near 70 °F and 35% relative humidity sits around 7%, and one held near 70 °F and 50% relative humidity sits closer to 9%. Specifying a single national number instead of the range the building will actually hold is what puts a correctly manufactured floor into the wrong climate. {note}
+### The differential limit, not the absolute reading, is what predicts post-installation movement. A floor drier than its substrate absorbs moisture and cups; a floor wetter than its substrate releases moisture and gaps. Wider boards concentrate the same percentage change into a larger dimensional change, which is why the permitted differential tightens as face width grows. {note}
+### A pin meter reading is species-dependent because electrical resistance varies with density; reading white oak on a setting calibrated for pine reports a moisture content that can be off by more than the entire differential allowance. {note}
−## Concrete Slab Moisture {toc}
+# Substrate Moisture Testing and Control {toc}
−### The acceptable concrete substrate moisture condition is a governing service condition for wood flooring and shall be established by test before installation and confirmed against the lower of the system manufacturer's limit and the limit of this standard.
+## Concrete Slab Moisture Testing {toc}
+### Concrete slabs shall be tested for internal relative humidity in accordance with ASTM F2170 before flooring, adhesive, or moisture control material is ordered.
+
```datasheet
−label: Maximum Slab Internal Relative Humidity (ASTM F2170)
+label: Maximum Slab Internal Relative Humidity, ASTM F2170
type: range
−unit: "% RH"
−options:
− min: 70
− max: 90
− step: 5
−setpoints: [70, 75, 80, 85, 90]
+unit: '% RH'
+min: 60
+max: 100
+step: 1
+setpoints: [60, 65, 70, 75, 80, 85, 90, 95, 100]
default: 75
```
```datasheet
−label: Maximum Moisture Vapor Emission Rate (ASTM F1869, where used)
+label: Maximum Moisture Vapor Emission Rate, ASTM F1869
type: range
−unit: lb/1000 sq ft/24 hr
−options:
− min: 3
− max: 5
− step: 1
−setpoints: [3, 5]
+unit: lb/1000 ft²/24 h
+min: 1
+max: 10
+step: 0.5
+setpoints: [1, 2, 3, 4, 5, 7, 10]
default: 3
```
−### The relative humidity within the concrete slab, measured by in-situ probe per ASTM F2170 at 40% of the slab depth for slabs drying from one side, shall not exceed the limit stated without a moisture-mitigation measure rated for the actual reading.
−### Where moisture vapor emission rate is used as a screening or supplementary measure per ASTM F1869, the rate shall not exceed 3 lb/1000 sq ft/24 hr for most adhesive glue-down, or 5 lb where a urethane adhesive with an integral moisture-control limit is specified.
−### Failure to test the slab — or testing only with the surface calcium chloride method on a slab on or below grade — is the single largest cause of adhesive failure, cupping, and delamination claims, because a slab interior can remain wet long after the surface reads dry. ASTM F2170 internal relative humidity is the reliable measure for slabs on or below grade. {note}
+```datasheet
+label: Maximum Slab Surface pH
+type: range
+min: 7
+max: 12
+step: 0.5
+setpoints: [7, 8, 9, 10, 11, 12]
+default: 10
+```
−# Wood Flooring Products {toc}
+### In-situ probes shall be placed at 40% of the slab depth for slabs drying from one side and at 20% of the slab depth for slabs drying from two sides.
+### Probes shall be allowed to equilibrate for the period ASTM F2170 requires before a reading is recorded.
+### The slab shall be held within the specified in-service interior temperature and relative humidity range for not less than 48 hours before testing and throughout the test period.
+### Testing shall include three test locations in the first 1000 ft² of slab area and one additional location for each additional 1000 ft² or fraction thereof.
+### Test locations shall include the areas of the slab most likely to be wet, including areas adjacent to below-grade walls, at construction joints, at the lowest point of the slab, and beneath areas that were exposed to weather.
+### The slab surface pH shall be tested in accordance with ASTM F710 at the same frequency as the relative humidity testing.
+### Where the measured internal relative humidity, emission rate, or surface pH exceeds the limit stated in the datasheet or the limit published by the flooring or adhesive manufacturer, whichever is lower, flooring shall not be installed until a moisture control measure rated for the measured condition is installed.
+### Slabs on grade and below grade shall be confirmed to be above [[parameter: seasonal-high-groundwater-elevation]] before wood flooring is installed.
+### The Contractor shall bear the cost of retesting after a failed test and the cost of any moisture control measure made necessary by a slab condition the Contractor's own work caused.
+### ASTM F1869 calcium chloride testing measures only the top 1/2 in to 3/4 in of the slab, so a slab whose surface has dried while its interior remains saturated passes it and fails in service. ASTM F2170 internal relative humidity reads the slab at depth and is the reliable measure for slabs on or below grade. {note}
+### Electrical impedance meters covered by ASTM F2659 are useful for mapping wet areas quickly and choosing where to place probes, but they are a comparative screening tool and not a substitute for an ASTM F2170 result. {note}
+### High slab surface pH is a separate failure path from moisture: alkalinity generated as water migrates through cement paste attacks adhesive polymers directly, so a slab can be dry enough and still degrade the bond. {note}
+### A slab on grade is never finished drying in the way a slab above grade is. Ground moisture supplies it continuously, so the question is not whether the slab dries out but whether the under-slab vapor retarder and any topical moisture control measure hold the drive below what the assembly tolerates. {note}
−## Product Type {toc}
+## Wood Substrate Moisture {toc}
−### The product type is the foundational selection; it determines which substrates and attachment methods are available, the achievable board width, the dimensional stability, and the refinishing lifecycle. {note}
+### Wood substrates shall be tested for moisture content before flooring is delivered and again immediately before installation.
−### The product type shall be selected for the substrate, the climate stability of the space, and the attachment method, and shall be indicated in the [[drawing: finish schedule]].
+```datasheet
+label: Maximum Wood Substrate Moisture Content
+type: range
+unit: '%'
+min: 8
+max: 14
+step: 0.5
+setpoints: [8, 9, 10, 11, 12, 13, 14]
+default: 12
+```
+### Testing shall include not fewer than 20 readings for each 1000 ft² of substrate area, distributed across the area and including locations at exterior walls and above unconditioned space.
+### Crawl spaces beneath a wood substrate shall be ventilated or conditioned and shall have a ground vapor retarder installed before flooring is delivered.
+### Where the wood substrate exceeds the specified moisture content, the Contractor shall identify and correct the moisture source before installing flooring.
+### A wood substrate over a vented crawl space or an unconditioned space is exposed to a climate on its underside that the interior conditioning never reaches, which is why the readings at those locations govern rather than an average across the floor. {note}
+
+## Moisture Control Measures {toc}
+
+### The moisture control measure shall be as indicated in the datasheet.
+
```datasheet
−label: Product Type
+label: Moisture Control Measure
type: select
−drawing_ref: true
+derived: "the measured slab internal relative humidity and the moisture limits published for the specified flooring and adhesive"
options:
− - "Solid strip flooring (tongue-and-groove, face width 3 in or less)"
− - "Solid plank flooring (tongue-and-groove, face width over 3 in)"
− - "Engineered multi-ply strip flooring (hardwood face veneer)"
− - "Engineered multi-ply plank flooring (hardwood face veneer)"
− - "Wood parquet tile / block (finger block or pattern)"
− - "Maple gymnasium sports floor (over resilient sleeper system)"
− - "End-grain wood block (industrial / specialty)"
−default: "Engineered multi-ply plank flooring (hardwood face veneer)"
+ - "No separate moisture control measure in the assembly"
+ - "Asphalt-saturated felt or building paper slip sheet"
+ - "Polyethylene sheet vapor retarder beneath a panel or sleeper assembly"
+ - "Asphalt-laminated kraft vapor retarder beneath a panel or sleeper assembly"
+ - "Trowel- or roller-applied moisture control membrane bonded to the slab"
+ - "Two-component epoxy moisture vapor barrier bonded to the slab"
+ - "Sheet membrane moisture control layer bonded to the slab"
+ - "Adhesive with an integral moisture control function"
+default: derived
```
−### Solid wood is milled from a single piece of hardwood and can be sanded and refinished many times, but it moves the most with humidity and is restricted to above-grade wood subfloors or to sleeper assemblies over concrete; it is not appropriate directly on or below grade. Engineered flooring is built up from a hardwood face veneer over a cross-laminated plywood or HDF core, which dramatically reduces dimensional movement and allows installation over concrete on and above grade by glue-down or floating; its refinishing lifecycle is limited by the veneer thickness. Parquet is small finger blocks or patterned pieces, usually glued down. Maple gymnasium floors are a specialty assembly of solid hard maple over a sprung or pad-and-sleeper system engineered for athletic performance. End-grain block, set with the grain vertical, is an industrial wearing surface, not a typical commercial finish. {note}
−## Species and Hardness {toc}
+### A topical moisture control membrane shall be rated by its manufacturer for the internal relative humidity actually measured in the slab, and a generic rating shall not be accepted.
+### A topical moisture control membrane shall be installed over the full slab area receiving flooring and shall be continuous at penetrations, cold joints, and the perimeter.
+### The adhesive used over a topical moisture control membrane shall be a product the membrane manufacturer approves in writing for use over that membrane.
+### Where a moisture control measure is installed, the Contractor shall test the cured membrane for pinholes, holidays, and bond in accordance with the membrane manufacturer's written procedure, and shall repair defects before flooring is installed.
+### The measure is selected from the reading, not the reverse. A membrane rated to 90% relative humidity installed on a slab reading 97% fails as reliably as no membrane at all, and the manufacturer's rating is the only number that connects the two. {note}
+### A slip sheet, a sheet vapor retarder, and a bonded membrane solve different problems. A slip sheet lets a floating or sleeper assembly move independently of the slab; a sheet retarder blocks vapor beneath an assembly that is not bonded to the slab; a bonded membrane both blocks vapor and provides the surface the flooring adhesive bonds to. Substituting one for another changes what the assembly can do. {note}
+# Flooring Construction and Format {toc}
+
+## The flooring construction shall be as indicated in the datasheet.
+
```datasheet
+label: Flooring Construction
+type: select
+options:
+ - "Solid sawn"
+ - "Engineered, veneer face over a cross-laminated plywood core"
+ - "Engineered, veneer face over a high-density fiberboard core"
+ - "Engineered, veneer face over an edge-glued lumber core"
+ - "Engineered, sawn face over a cross-laminated plywood core"
+ - "End-grain block"
+```
+
+## The board format shall be as indicated in the datasheet.
+
+```datasheet
+label: Board Format
+type: select
+options:
+ - "Strip"
+ - "Plank"
+ - "Mixed-width plank"
+ - "Parquet tile"
+ - "Parquet block"
+ - "Herringbone"
+ - "Chevron"
+ - "Feature border with field"
+```
+
+## Solid sawn flooring shall not be bonded directly to a concrete slab on or below grade.
+## Engineered flooring shall comply with ANSI/HPVA EF for core construction, face veneer thickness, moisture content, machining tolerance, and bond-line integrity under the three-cycle-soak delamination test.
+## Engineered flooring containing a composite wood core shall comply with the formaldehyde emission standards of 40 CFR Part 770.
+## End-grain block flooring shall be specified with the block height, the treatment or impregnation, and the setting bed identified in the submittal.
+## The extent of each flooring construction and format shall be as indicated on [[drawing: the room finish schedule]].
+## Solid sawn flooring is milled from one piece of wood, can be resanded through most of its thickness, and moves the most with a change in moisture content. Engineered flooring puts a hardwood face over a cross-laminated or fiberboard core that restrains movement across the width, which is what lets it go over a slab on grade and in wider face widths; the tradeoff is that only the face veneer can ever be sanded. {note}
+## Core construction is not interchangeable. A cross-laminated plywood core carries fasteners and tolerates incidental moisture; a high-density fiberboard core is dimensionally very stable and dense but swells irreversibly when wetted; an edge-glued lumber core behaves closest to solid wood. Where a slab reading sits near the limit or a wet-use area adjoins the floor, the core's response to liquid water is the property that separates them. {note}
+## End-grain block presents the cut ends of the fibers as the wearing surface, which is why it resists point loads and abrasion far better than face-grain flooring of the same species and why it appears in shops and industrial spaces rather than as a conventional finish. {note}
+## Parquet, herringbone, and chevron assemblies are small units set in a pattern, so their movement accumulates in two directions rather than one; the perimeter allowance and the substrate flatness that a pattern floor needs are correspondingly greater than for a straight-laid floor of the same material. {note}
+
+# Species, Cut, and Grade {toc}
+
+## Species {toc}
+
+### The wood species shall be as indicated in the datasheet.
+
+```datasheet
label: Wood Species
type: select
−drawing_ref: true
options:
− - "Red oak (domestic, Janka ≈1290 lbf)"
− - "White oak (domestic, Janka ≈1360 lbf)"
− - "Hard (sugar) maple (domestic, Janka ≈1450 lbf)"
− - "Hickory / pecan (domestic, Janka ≈1820 lbf)"
− - "Ash (domestic, Janka ≈1320 lbf)"
− - "American walnut (domestic, Janka ≈1010 lbf)"
− - "Specified imported/exotic species (by botanical name, Janka per submittal)"
−default: "White oak (domestic, Janka ≈1360 lbf)"
+ - "Red oak"
+ - "White oak"
+ - "Hard maple"
+ - "Soft maple"
+ - "Yellow birch"
+ - "American beech"
+ - "Hickory"
+ - "Pecan"
+ - "White ash"
+ - "American black walnut"
+ - "American black cherry"
+ - "American sycamore"
+ - "Douglas fir"
+ - "Southern yellow pine"
+ - "Eastern white pine"
+ - "Heart pine, reclaimed or resawn"
+ - "Jatoba (Hymenaea courbaril)"
+ - "Ipe (Handroanthus spp.)"
+ - "Cumaru (Dipteryx odorata)"
+ - "Santos mahogany (Myroxylon balsamum)"
+ - "Sapele (Entandrophragma cylindricum)"
+ - "Teak (Tectona grandis)"
```
+### Imported and tropical species shall be identified by botanical name in addition to any common or trade name.
+### The Contractor shall submit chain-of-custody or legal-harvest documentation for imported species where the Contract Documents require it.
+### Common trade names are not unique. More than one botanical species is sold as Brazilian cherry, and more than one as mahogany, with hardness and dimensional stability that differ substantially between them, so the botanical name is what makes a substitution detectable at submittal review rather than at delivery. {note}
+### Janka side hardness measures resistance to indentation and is the property most often used to match a species to traffic. Across the selectable range it varies by nearly a factor of ten, and it is one input among several: dimensional stability, grain figure, color stability under ultraviolet light, availability in the specified width, and cost all move independently of it. The values below are nominal published averages for kiln-dried material and vary by a few percent between sources and growing regions. {note}
+
+| Species | Nominal Janka side hardness (lbf) |
+|---------|-----------------------------------|
+| Eastern white pine | 380 |
+| Douglas fir | 660 |
+| American sycamore | 770 |
+| Southern yellow pine | 870 |
+| Soft maple | 950 |
+| American black cherry | 950 |
+| Teak | 1000 |
+| American black walnut | 1010 |
+| Heart pine | 1225 |
+| Yellow birch | 1260 |
+| Red oak | 1290 |
+| American beech | 1300 |
+| White ash | 1320 |
+| White oak | 1360 |
+| Sapele | 1410 |
+| Hard maple | 1450 |
+| Hickory and pecan | 1820 |
+| Santos mahogany | 2200 |
+| Jatoba | 2350 |
+| Cumaru | 3540 |
+| Ipe | 3680 |
+
+### Dimensional stability and hardness are different properties and do not track together: quartersawn white oak moves less across its width than plainsawn hickory that is substantially harder, so a floor chosen for dent resistance alone can still be the one that gaps. {note}
+
+## Sawing Method {toc}
+
+### The sawing method for solid flooring and the cut of the face for engineered flooring shall be as indicated in the datasheet.
+
```datasheet
−label: Minimum Janka Hardness
−type: range
−unit: lbf
+label: Sawing Method
+type: select
options:
− min: 1000
− max: 1820
− step: 10
−setpoints: [1010, 1290, 1360, 1450, 1820]
−default: 1290
+ - "Plain sawn"
+ - "Rift sawn"
+ - "Quarter sawn"
+ - "Rift and quartered"
+ - "Live sawn"
+ - "Mill run, mixed sawing"
+ - "Rotary peeled veneer face"
+ - "Sliced veneer face"
+ - "Sawn veneer face"
+default: "Plain sawn"
```
−### The species shall be selected for the hardness, dimensional stability, appearance, and cost appropriate to the application, and shall be specified by name and minimum Janka hardness.
−### Imported and exotic species shall be specified by botanical name in addition to any common or trade name.
−### Janka hardness measures resistance to denting and wear and should be matched to traffic: red oak at about 1290 lbf is the residential and light-commercial benchmark, hard maple at about 1450 lbf is preferred for heavy commercial corridors and retail, and gymnasium floors use northern hard maple graded under the MFMA rules. Common names are ambiguous — "Brazilian cherry" alone can denote more than one species with different hardness and stability — so specifying the botanical name or a minimum Janka value prevents a substitution that looks similar but performs differently. {note}
+### Plain sawn material is cut tangentially to the growth rings and produces the cathedral figure most people picture as a wood floor; it is the highest-yield cut and therefore the least expensive. Quartersawn and rift material is cut closer to radially, showing straight grain and, in oak, medullary ray flake, and it moves roughly half as much across its width for the same change in moisture content. Where the interior humidity range is wide or the face width is large, that difference in movement is the reason to pay the yield penalty. {note}
+### Veneer cut governs the appearance of an engineered face the same way sawing governs a solid board. A rotary-peeled face carries a broad, repeating figure that reads as plywood at close range; a sliced or sawn face is visually indistinguishable from solid material of the same cut, and a sawn face can be thick enough to sand. {note}
−## Grade {toc}
+## Appearance Grade {toc}
+### The appearance grade shall be as indicated in the datasheet.
+
```datasheet
−label: Flooring Grade
+label: Appearance Grade
type: select
−drawing_ref: true
options:
− - "Clear / Premier (most uniform color and grain, fewest character marks)"
− - "Select and Better (limited character marks)"
− - "No. 1 Common / Character (moderate color variation and character marks)"
− - "No. 2 Common / Rustic (pronounced variation, knots, and character marks)"
−default: "Select and Better (limited character marks)"
+ - "Clear"
+ - "Select"
+ - "Select and Better"
+ - "No. 1 Common"
+ - "No. 2 Common"
+ - "No. 3 Common"
+ - "First Grade, MFMA northern hard maple"
+ - "Second Grade, MFMA northern hard maple"
+ - "Third Grade, MFMA northern hard maple"
+ - "Character grade defined by the approved sample"
+ - "Rustic grade defined by the approved sample"
```
−### The flooring grade shall be specified by reference to the governing grading standard — NWFA/NOFMA for solid hardwood, ANSI/HPVA EF 2020 for engineered — not by a trade grade name alone.
−### Grade governs the permitted amount of color variation, sapwood, knots, and other character marks, not the structural quality of the wood: a Clear grade is the most uniform, while No. 2 Common (Rustic) deliberately shows pronounced variation and character. Grade nomenclature is not interchangeable between standards — NWFA/NOFMA "Clear" is not the same definition as an ANSI/HPVA EF 2020 A-Grade, and each manufacturer's proprietary grade names map differently again — so the specification must name the standard the grade is measured against. {note}
+### The grade shall be certified against the grading rule governing the specified construction and species, as set out in the table below.
−## Dimensions and Profile {toc}
+| Product | Governing grading rule |
+|---------|------------------------|
+| Solid unfinished hardwood flooring | NWFA/NOFMA Unfinished |
+| Solid factory-finished hardwood flooring | NWFA/NOFMA Factory Finished |
+| Engineered flooring | ANSI/HPVA EF |
+| Northern hard maple, beech, and birch sports flooring | MFMA Grading Rules |
+| Reclaimed and remilled flooring | The project-specific grade defined in the approved submittal |
+### Where a proprietary grade name is proposed, the submittal shall state the standard grade it corresponds to and the specific character marks, color range, and defects the proprietary grade admits.
+### Appearance grade governs the permitted extent of color variation, sapwood, knots, mineral streak, and other character marks; it does not describe the structural quality or the milling accuracy of the wood, both of which the grading rule fixes independently of grade. {note}
+### Grade nomenclature is not portable between rules. A NWFA/NOFMA Clear is not defined the same way as an ANSI/HPVA EF top grade, MFMA First Grade is defined against different criteria again, and manufacturers' proprietary names map to none of them consistently, which is why the grading rule has to be named alongside the grade. {note}
+### A lower appearance grade is not a lower-quality floor. No. 2 Common and rustic grades are specified deliberately where visible knots and color variation are the intended appearance, and they hide wear and repair better than a uniform clear grade does. {note}
+
+# Dimensions, Profile, and Texture {toc}
+
+## Board Dimensions {toc}
+
+### The nominal thickness and face width of the flooring shall be as indicated in the datasheet.
+
```datasheet
label: Nominal Thickness
−type: select
+type: range
unit: in
−drawing_ref: true
−options:
− - "3/4 in (solid strip/plank; heavy-duty engineered)"
− - "1/2 in (engineered plank, typical commercial)"
− - "3/8 in (engineered or thin solid)"
− - "5/16 in (thin solid / parquet)"
−default: "1/2 in (engineered plank, typical commercial)"
+min: 0.25
+max: 1
+step: 0.0625
+setpoints: [0.25, 0.3125, 0.375, 0.5, 0.625, 0.75, 1]
```
```datasheet
label: Face Width
−type: select
+type: range
unit: in
−drawing_ref: true
−options:
− - "2-1/4 in (standard strip)"
− - "3 in (narrow plank)"
− - "5 in (plank)"
− - "7 in (wide plank)"
− - "Over 7 in (wide plank, engineered recommended)"
−default: "5 in (plank)"
+min: 1.5
+max: 12
+step: 0.25
+setpoints: [1.5, 2.25, 3, 3.25, 4, 5, 6, 7, 8, 9, 10, 12]
```
```datasheet
−label: Edge and End Profile
−type: radio
−options:
− - "Tongue-and-groove, end-matched (T&G all four edges)"
− - "Tongue-and-groove, square edge (no microbevel)"
− - "Tongue-and-groove, micro-beveled / eased edge"
− - "Click-lock profile (engineered floating)"
−default: "Tongue-and-groove, micro-beveled / eased edge"
+label: Engineered Face Veneer Thickness
+type: range
+unit: mm
+min: 0.6
+max: 6
+step: 0.1
+setpoints: [0.6, 1, 2, 3, 4, 5, 6]
```
−### The nominal thickness, face width, and edge and end profile shall be as specified and coordinated with the attachment method and the refinishing expectation.
−### Wider boards move more across their width with the same change in moisture content than narrow boards do, so wide solid plank is more prone to visible gapping and cupping and is more reliably delivered as an engineered product; thickness governs both the available attachment method (3/4-inch product accepts cleats and staples; thinner solid takes finer staples) and how many times a floor can be resanded. A micro-beveled edge hides minor height variation between boards and is common on prefinished flooring; a true square edge yields a flush, monolithic surface but demands a flatter substrate and is typical of site-finished work. {note}
+### The face veneer thickness requirement applies where the flooring construction indicated in the datasheet is engineered.
+### The face veneer of engineered flooring shall be measured and reported to the tolerance ANSI/HPVA EF requires.
+### Nominal thickness governs which attachment methods are available and how many times the floor can be resanded: 3/4 in solid material accepts cleats and staples and carries roughly 3/16 in of wear layer above the tongue, while thinner solid material takes finer fasteners and tolerates fewer sandings. {note}
+### Face width and dimensional movement scale together. A board twice as wide moves roughly twice as far across its face for the same change in moisture content, so the same seasonal swing that is invisible on 2-1/4 in strip opens a readable gap on 7 in plank. That is why wide formats are more often supplied as engineered material and why the permitted moisture differential tightens at 3 in. {note}
+### Only the face veneer of an engineered board can be sanded. Below roughly 2 mm a veneer will not survive a full sanding; 3 mm to 4 mm supports one to two light resands over a commercial service life; and a sawn face of 5 mm to 6 mm approaches the refinishing life of solid material. Specifying a thin veneer for a floor the Owner expects to refinish converts a recoat into a replacement. {note}
−## Engineered Wear Layer {toc}
+## Joinery and Edge Profile {toc}
+### The joinery system shall be as indicated in the datasheet.
+
```datasheet
−label: Engineered Veneer (Wear Layer) Thickness
+label: Joinery System
type: select
−unit: mm
−drawing_ref: true
options:
− - "2 mm (light residential, not refinishable)"
− - "3 mm (commercial, one light resand)"
− - "4 mm (commercial, refinishable)"
− - "6 mm (heavy commercial, two-sand lifecycle)"
−default: "4 mm (commercial, refinishable)"
+ - "Tongue and groove, end matched"
+ - "Tongue and groove, square ends"
+ - "Mechanical locking profile"
+ - "Square edge, blind splined"
+ - "Square edge, face fastened"
+ - "Butt joint, unmatched"
```
−### For engineered flooring, the hardwood face veneer (wear layer) thickness shall be specified per ANSI/HPVA EF 2020 for the intended refinishing lifecycle.
−### The wear layer is the only part of an engineered board that can be sanded; a 2 mm veneer is essentially never refinishable, 3 mm to 4 mm permits one to two light resands over a commercial lifecycle, and 6 mm supports a genuine two-sand lifecycle approaching that of solid flooring. Specifying a thin wear layer for a floor expected to be refinished is a false economy that forces a full replacement when the floor wears. {note}
+### The edge profile shall be as indicated in the datasheet.
+```datasheet
+label: Edge Profile
+type: select
+options:
+ - "Square edge"
+ - "Micro-beveled edge"
+ - "Eased edge"
+ - "Beveled edge"
+ - "Pillowed edge"
+```
+
+### Flooring installed by a floating method shall have a joinery system the flooring manufacturer approves in writing for floating installation.
+### A square edge yields a flush, monolithic plane and is what site sanding produces, but it demands a flatter substrate and tighter thickness tolerance because any height difference between adjacent boards shows as a ridge. A micro-bevel or eased edge absorbs that difference in a shadow line, which is why factory-finished flooring is usually supplied with one. {note}
+### A mechanical locking profile joins boards without adhesive or fasteners and is what makes a floating installation possible; it also means the floor's dimensional behavior is governed entirely by the perimeter allowance, because nothing restrains it in the field. {note}
+
## Surface Texture {toc}
+### The surface texture shall be as indicated in the datasheet.
+
```datasheet
label: Surface Texture
−type: radio
−drawing_ref: true
+type: select
options:
− - "Smooth / flat (sanded)"
− - "Wire-brushed (open grain, hides wear)"
− - "Hand-scraped (artisan texture)"
− - "Skip-sawn / distressed"
−default: "Smooth / flat (sanded)"
+ - "Smooth, sanded"
+ - "Wire brushed"
+ - "Light hand scraped"
+ - "Heavy hand scraped"
+ - "Circular sawn"
+ - "Skip sawn"
+ - "Distressed"
+default: "Smooth, sanded"
```
−### The surface texture shall be as selected and consistent with the finish and grade.
−### A smooth, flat surface is the conventional commercial and institutional finish; wire-brushing opens the grain and is effective at hiding scuffs and wear in high-traffic areas; hand-scraped and skip-sawn textures are appearance choices that read as rustic or artisan. Texture is largely an appearance and wear-concealment decision and does not change the wood's structural performance. {note}
+### Textured flooring shall be factory textured unless the Contract Documents require site texturing, in which case the texture shall match the accepted mock-up.
+### Texture changes how the floor conceals wear rather than how it resists it. Wire brushing removes the soft earlywood and leaves an open grain that breaks up scuffs and scratches optically; scraped and sawn textures do the same at a coarser scale. None of them adds hardness, and all of them make a floor harder to clean and harder to sand flat later. {note}
−# Attachment and Substrate {toc}
+# Substrate Preparation {toc}
−## Attachment Method {toc}
+## Substrate Flatness {toc}
+### The substrate shall be prepared flat within the tolerance indicated in the datasheet, measured as the maximum deviation from a 10 ft straightedge.
+
```datasheet
−label: Attachment Method
+label: Substrate Flatness Tolerance in 10 ft
+type: range
+unit: in
+min: 0.0625
+max: 0.25
+step: 0.0625
+setpoints: [0.0625, 0.125, 0.1875, 0.25]
+```
+
+### Substrates receiving adhesive-bonded or floating flooring shall be flat within 3/16 in in 10 ft or a tighter tolerance where the datasheet or the flooring manufacturer requires one.
+### Substrates receiving mechanically fastened flooring shall be flat within 1/4 in in 10 ft or a tighter tolerance where the datasheet or the flooring manufacturer requires one.
+### High spots shall be ground or sanded down and low spots shall be filled with a patching or leveling compound the flooring and adhesive manufacturers approve in writing.
+### The Contractor shall verify flatness after patching and before flooring is installed, and shall record the locations checked.
+### The party whose work created an out-of-tolerance condition shall bear the cost of correcting it, and where the parties disagree about the origin of the condition the Architect of Record shall make the initial determination.
+### A floating floor is the least forgiving assembly because nothing holds it down to follow the substrate. Humps become bearing points that telegraph and creak, hollows leave the locking joints unsupported and working in bending, and both show up as noise long before they show up as damage. Bonded and fastened floors follow the substrate instead, which trades a flatness problem for a visible waviness problem. {note}
+
+## Nailable Assemblies Over Concrete {toc}
+
+### Where the attachment method requires a nailable substrate over a concrete slab, the assembly shall be as indicated in the datasheet.
+
+```datasheet
+label: Nailable Assembly Over Concrete
type: select
−drawing_ref: true
options:
− - "Nail / cleat-down (wood subfloor only)"
− - "Staple-down (wood subfloor only)"
− - "Full-spread adhesive glue-down (concrete or wood)"
− - "Floating, glued tongue-and-groove (engineered)"
− - "Floating, click-lock (engineered)"
−default: "Full-spread adhesive glue-down (concrete or wood)"
+ - "Not applicable to a bonded or floating installation on the slab"
+ - "Single layer of wood structural panel fastened to the slab over a vapor retarder"
+ - "Two offset layers of wood structural panel over a vapor retarder"
+ - "Wood sleepers set in mastic with a wood structural panel subfloor"
+ - "Wood sleepers set in mastic with flooring fastened directly to the sleepers"
+ - "Free-floating wood structural panel subfloor over a vapor retarder"
+ - "Proprietary anchored sleeper and resilient pad system"
```
−### The attachment method shall be compatible with both the product type and the substrate, and shall be indicated on the [[drawing: finish schedule]].
−### Floating installation shall be used only with engineered products designed for it, not with solid 3/4-inch flooring.
−### Nail- and staple-down attachment requires a wood subfloor; nail- or staple-down attachment shall not be specified over a bare concrete slab unless a wood sleeper assembly or nailable underlayment over a vapor retarder is provided.
−### Each attachment method suits a different combination of product and substrate: nail- and staple-down fastens solid (and some engineered) flooring through the tongue into a wood subfloor and is the traditional method for solid 3/4-inch product; full-spread glue-down bonds the flooring to concrete or wood with adhesive and is the common method for engineered flooring and parquet over slabs; floating leaves the flooring unattached to the substrate, joined only at its edges by glue or a click profile, riding on an underlayment, and is limited to engineered products. Specifying floating for solid strip, or nail-down without providing the wood substrate it requires, is a common error that voids the manufacturer warranty and creates a scope gap between the finish and the substrate trades. {note}
+### Sleepers and wood structural panels installed over concrete shall be kiln dried and shall be at a moisture content within the differential limit of this standard before flooring is installed.
+### A vapor retarder shall be installed between the concrete slab and any wood sleeper or panel assembly, lapped and sealed at joints and turned up at the perimeter.
+### Wood structural panels installed over concrete shall be spaced with a gap at panel edges and at the perimeter as the panel manufacturer requires, and panel joints shall be offset from one another where two layers are used.
+### Fasteners driven into a concrete slab shall not penetrate a post-tensioning tendon, a conduit, or a radiant heating element, and the Contractor shall scan the slab and mark obstructions before fastening.
+### A nailable assembly over a slab does two things at once: it creates the wood substrate that fasteners need, and it lifts the flooring off the slab so the wood is not in direct contact with the concrete's moisture. A free-floating panel assembly adds a third property, letting the whole floor move as a unit over a slab that is not flat enough to fasten to. {note}
+### Sleeper assemblies raise the finish floor by their own depth plus the subfloor and flooring above them, which is a dimension that has to be resolved against door undercuts, stair risers, and adjacent finishes before the framing is set rather than after. {note}
−## Fasteners (Nail/Staple-Down) {toc}
+## Acoustical Underlayment {toc}
+### The acoustical underlayment shall be as indicated in the datasheet.
+
```datasheet
−label: Fastener Type and Size
+label: Acoustical Underlayment
type: select
options:
− - "16-gauge cleats, 1-3/4 in to 2 in (solid 3/4 in)"
− - "15.5-gauge staples, 1-3/4 in to 2 in (solid 3/4 in)"
− - "18-gauge staples, 1-1/2 in (3/8 in to 1/2 in solid/engineered)"
−default: "16-gauge cleats, 1-3/4 in to 2 in (solid 3/4 in)"
+ - "No acoustical underlayment in the assembly"
+ - "Cork sheet underlayment"
+ - "Recycled rubber sheet underlayment"
+ - "Closed-cell foam underlayment"
+ - "Entangled or needled fiber mat underlayment"
+ - "Sound control adhesive with an integral resilient film"
+ - "Poured gypsum topping over a resilient mat"
```
```datasheet
−label: Fastener Spacing
+label: Minimum Impact Sound Improvement, ASTM E2179
type: range
−unit: in
+unit: dB
+min: 0
+max: 30
+step: 1
+```
+
+### The acoustical underlayment shall be a product the flooring manufacturer approves in writing for use beneath the specified flooring and attachment method.
+### Where the floor-ceiling assembly separates dwelling units or guest rooms, the assembly shall meet the impact insulation class the adopted building code requires, verified by laboratory test to ASTM E492 or by field test to ASTM E1007 as the Contract Documents direct.
+### The impact sound improvement value from ASTM E2179 describes what a covering adds to a bare concrete reference floor, so it compares coverings to one another honestly but does not by itself predict the rating of a specific assembly; that comes from an assembly test. {note}
+### An acoustical underlayment is a compressible layer between the flooring and the substrate, and every property that makes it effective acoustically also makes the floor above it softer underfoot and more dependent on the flooring manufacturer's written approval for the attachment method. {note}
+
+# Attachment {toc}
+
+## Attachment Method {toc}
+
+### The attachment method shall be as indicated in the datasheet.
+
+```datasheet
+label: Attachment Method
+type: select
options:
− min: 6
− max: 8
− step: 1
−setpoints: [6, 8]
−default: 8
+ - "Blind nailed with cleats"
+ - "Blind stapled"
+ - "Full spread adhesive"
+ - "Full spread adhesive with supplemental mechanical fastening"
+ - "Floating with glued edge joints"
+ - "Floating with mechanical locking joints"
+ - "Set in mastic for parquet and block"
+ - "Set in bitumen for end-grain block"
```
−### Fasteners for nail- and staple-down installation shall conform to ASTM F1667 and shall be the type and size matched to the flooring thickness per the NWFA Installation Guidelines.
−### For solid 3/4-inch flooring, cleats or staples shall be installed at 6 in to 8 in along each board and within 1 in to 3 in of each board end, with additional fasteners as the board length and width require.
−### Fastener size is correlated to flooring thickness: 16-gauge cleats or 15.5-gauge staples 1-3/4 in to 2 in long for solid 3/4-inch product, and finer 18-gauge staples 1-1/2 in long for 3/8-inch to 1/2-inch material. An undersized or under-spaced fastening schedule lets boards move and squeak; an oversized fastener can split the tongue. {note}
+### Mechanically fastened attachment shall be used only over a wood substrate or a nailable assembly provided in accordance with this standard.
+### Unless the datasheet indicates a floating attachment method, solid sawn flooring shall not be installed by a floating method.
+### The attachment method shall be one the flooring manufacturer approves in writing for the specified product over the specified substrate.
+### Each attachment method suits a different combination of product and substrate. Mechanical fastening drives cleats or staples through the tongue into a wood substrate and holds each board independently. Full-spread adhesive bonds the flooring to the substrate across its whole area, which works over concrete and restrains movement board by board. Floating leaves the flooring unattached to the substrate, joined only at its edges, so the entire field moves as one panel and all of its movement has to be absorbed at the perimeter. {note}
+### The failure mode of each method differs. A fastened floor squeaks and works loose; a bonded floor develops hollow spots and, where the substrate is wet, delaminates or cups; a floating floor telegraphs the substrate, clicks underfoot, and buckles if the perimeter allowance is short anywhere around it. {note}
−## Adhesive (Glue-Down) {toc}
+## Fasteners {toc}
+### Fasteners shall conform to ASTM F1667 and shall be as indicated in the datasheet.
+
```datasheet
−label: Adhesive Type
+label: Fastener Type
type: select
options:
− - "Urethane (full-spread, moisture-tolerant)"
− - "MS polymer / silane-modified (full-spread, low-VOC)"
− - "Epoxy (specialty / high-strength)"
− - "Pressure-sensitive (parquet / repositionable only)"
−default: "Urethane (full-spread, moisture-tolerant)"
+ - "Barbed flooring cleat"
+ - "Chisel point flooring staple"
+ - "Screw shank flooring nail"
+ - "Ring shank flooring nail"
+ - "Cut flooring nail"
```
```datasheet
−label: Adhesive Trowel Notch
−type: radio
+label: Fastener Gauge
+type: select
+derived: "the nominal thickness of the flooring, per the fastener schedule of the NWFA Installation Guidelines"
options:
− - "3/32 in V-notch"
− - "1/8 in V-notch"
− - "1/4 in square notch (per adhesive manufacturer)"
−default: "1/8 in V-notch"
+ - "15.5 gauge"
+ - "16 gauge"
+ - "18 gauge"
+ - "20 gauge"
+default: derived
```
−### The adhesive shall be a full-spread urethane or MS-polymer adhesive for commercial glue-down installations, applied with the trowel notch and at the spread rate the adhesive manufacturer specifies for the flooring.
−### Pressure-sensitive adhesive shall not be used for full-spread plank glue-down in commercial traffic.
−### The adhesive shall be compatible with the flooring and, where the slab moisture approaches the limit, shall be a moisture-control adhesive rated for the measured condition.
−### Commercial glue-down demands a full-spread urethane or MS-polymer adhesive: these cure to a strong, slightly flexible bond, tolerate slab moisture better than other chemistries, and many include an integral moisture and crack-isolation function. Pressure-sensitive adhesive is repositionable and appropriate for parquet or tile but does not develop the bond a plank floor needs under rolling and foot traffic. Spread rate matters — too little adhesive starves the bond and leaves hollow spots, too much squeezes onto the face — so the specified trowel notch, typically a 3/32 in or 1/8 in V-notch yielding roughly 40 to 60 sq ft per gallon, is part of the requirement. {note}
+```datasheet
+label: Fastener Length
+type: range
+unit: in
+derived: "the nominal thickness of the flooring and the substrate assembly, per the fastener schedule of the NWFA Installation Guidelines"
+min: 1
+max: 2.5
+step: 0.25
+setpoints: [1, 1.25, 1.5, 1.75, 2, 2.25, 2.5]
+```
−## Substrate Type and Vapor Retarder {toc}
+```datasheet
+label: Fastener Spacing Along Each Board
+type: range
+unit: in
+derived: "the nominal thickness and face width of the flooring, per the fastener schedule of the NWFA Installation Guidelines"
+min: 3
+max: 12
+step: 1
+setpoints: [3, 4, 6, 8, 10, 12]
+```
+### Fasteners shall be installed within 1 in to 3 in of each board end.
+### Not fewer than two fasteners shall be installed in every board regardless of its length.
+### Fasteners in corrosive or high-humidity environments shall be stainless steel or shall carry a coating the fastener manufacturer rates for the exposure.
+### Pneumatic fastener drive pressure shall be adjusted on sample material at the start of each work shift and after any change in flooring lot, so that the fastener seats without crushing the tongue.
+### Fastener size follows flooring thickness because the fastener has to reach the substrate with adequate penetration without splitting the tongue it passes through. An undersized or under-spaced schedule leaves boards free to move against the substrate, which is the origin of most squeaks; an oversized fastener or excessive drive pressure splits the tongue and destroys the very joint the fastener was meant to secure. {note}
+
+## Adhesives {toc}
+
+### The adhesive shall be as indicated in the datasheet.
+
```datasheet
−label: Substrate Type
+label: Adhesive Type
type: select
−drawing_ref: true
options:
− - "Wood structural panel subfloor (above grade)"
− - "Concrete slab, above grade"
− - "Concrete slab, on grade"
− - "Concrete slab, below grade"
−default: "Concrete slab, on grade"
+ - "One-component moisture cure urethane"
+ - "Two-component urethane"
+ - "Silane modified polymer"
+ - "Silane modified urethane"
+ - "Epoxy"
+ - "Modified silicone"
+ - "Pressure sensitive acrylic"
+ - "Hot asphalt mastic for end-grain block"
```
+### The trowel notch shall be as indicated in the datasheet.
+
```datasheet
−label: Vapor Retarder / Moisture Mitigation
−type: radio
−drawing_ref: true
+label: Adhesive Trowel Notch
+type: select
+derived: "the adhesive manufacturer's published spread rate for the specified flooring construction, thickness, and face width"
options:
− - "None required (wood subfloor, or slab passes within limits)"
− - "Vapor retarder sheet under wood subfloor / sleepers (asphalt-laminated kraft or poly)"
− - "Penetrating moisture-control sealer on slab"
− - "Moisture-control membrane or moisture-control adhesive (rated for measured RH)"
−default: "None required (wood subfloor, or slab passes within limits)"
+ - "5/32 in V-notch"
+ - "3/16 in V-notch"
+ - "1/4 in V-notch"
+ - "3/16 in U-notch"
+ - "1/4 in U-notch"
+ - "1/4 in square notch"
+default: derived
```
−### The substrate type shall be identified and, where it is concrete on or below grade, the product and attachment method shall be limited to engineered or to a sleeper assembly, with the moisture-mitigation measure selected for the measured slab condition.
−### Where solid wood flooring is installed over concrete, a wood sleeper system or nailable subfloor over a vapor retarder shall be provided, and the vapor retarder and sleeper assembly shall be detailed on the [[drawing: details]].
−### Where the slab relative humidity exceeds the flooring or adhesive limit, the moisture-mitigation product shall be rated for the RH actually measured, not a generic value.
−### Solid wood directly bonded to on-grade or below-grade concrete is outside its appropriate use; either an engineered product is specified, or a raised sleeper assembly over a vapor retarder is built to create the wood substrate and the air space solid flooring requires. Where a mitigation measure is installed, the product must be matched to the measured slab RH, not selected generically. {note}
+### The adhesive shall be a product the flooring manufacturer approves in writing for the specified flooring over the specified substrate and moisture control measure.
+### Adhesive shall be spread only over the area that can be covered within the adhesive's published working time under the actual site temperature and humidity.
+### Flooring shall be set into the adhesive within the published working time, fully bedded, and rolled or weighted as the adhesive manufacturer requires to achieve full transfer.
+### The Contractor shall lift one board in every 500 ft² during installation to verify adhesive transfer to the back of the board, and shall record the results.
+### Adhesive squeezed onto the face of factory-finished flooring shall be removed immediately with the cleaner the adhesive manufacturer specifies.
+### Trowel notch is the mechanism that sets spread rate, and spread rate is the requirement. Too little adhesive starves the bond and leaves hollow-sounding areas; too much extends cure time, squeezes onto the face, and can float the boards out of plane. Because the correct rate depends on the flooring's back profile and the substrate's porosity as well as the adhesive itself, it is the adhesive manufacturer's published figure that governs. {note}
+### Chemistry determines what an adhesive tolerates. Moisture-cure and silane-modified products cure by reacting with ambient and substrate moisture and remain slightly elastic, which lets them accommodate the differential movement between wood and concrete; many carry an integral moisture and crack-isolation function. Pressure-sensitive adhesive stays permanently tacky and repositionable, which suits parquet and block but does not develop the shear strength a plank floor under rolling traffic needs. {note}
−## Subfloor Flatness {toc}
+# Expansion Provisions {toc}
+## A perimeter expansion space shall be provided at every wall, doorframe, column, threshold, cabinet base, and fixed object, sized as indicated in the datasheet.
+
```datasheet
−label: Subfloor Flatness Tolerance
−type: radio
−drawing_ref: true
+label: Perimeter Expansion Space
+type: range
+unit: in
+derived: "the nominal thickness and face width of the flooring and the manufacturer's published expansion allowance for the installed area"
+min: 0.25
+max: 1.5
+step: 0.0625
+setpoints: [0.25, 0.375, 0.5, 0.625, 0.75, 1, 1.25, 1.5]
+```
+
+## The intermediate expansion provision shall be as indicated in the datasheet.
+
+```datasheet
+label: Intermediate Expansion Provision
+type: select
options:
− - "3/16 in in 10 ft (nail/staple-down and glue-down)"
− - "1/8 in in 10 ft (floating installation)"
−default: "3/16 in in 10 ft (nail/staple-down and glue-down)"
+ - "No intermediate expansion provision in the field of the floor"
+ - "T-molding at doorways and at the maximum unbroken run published by the flooring manufacturer"
+ - "Concealed expansion joint with a removable cover"
+ - "Compressible filler strip at the perimeter of each bay"
+ - "Expansion void beneath the base and shoe at the perimeter"
```
−### The subfloor shall be flat within 3/16 in in 10 ft for nail-, staple-, and glue-down installation, and within 1/8 in in 10 ft for floating installation, per the NWFA Installation Guidelines.
−### High and low spots beyond the tolerance shall be ground down or filled with a compatible patching or self-leveling compound before installation.
−### A floating floor is least forgiving of an out-of-flat subfloor because it is not held down to follow the substrate; unsupported humps and hollows let the floor flex underfoot, telegraph as hollow spots, and stress the edge joints. Glue-down and nail-down are somewhat more tolerant but still require the stated flatness to bond and fasten uniformly. {note}
+## The perimeter expansion space shall equal or exceed the greater of the value indicated in the datasheet and the flooring manufacturer's published requirement.
+## The perimeter expansion space shall be left open and shall not be filled with adhesive, patching compound, sealant, or fasteners.
+## The perimeter expansion space shall be concealed by the base, shoe, threshold, or transition profile.
+## Continuous runs of flooring exceeding the flooring manufacturer's published maximum unbroken length or width shall be interrupted by an intermediate expansion provision.
+## Expansion provisions and their concealment shall be detailed on [[drawing: the flooring expansion and transition details]].
+## Wood expands across its width as it takes on moisture, and a floor installed tight to its boundaries has nowhere to put that expansion except upward. The perimeter space is the entire mechanism, and it fails silently: a gap that was left correctly and then filled with a bead of sealant or pinned by a fastener through the base is functionally no gap at all. {note}
+## Floating floors need the largest allowance because the whole field moves as one unit, and they need it continuously around the perimeter; a single point of contact anywhere restrains the entire floor and concentrates the movement elsewhere. {note}
−# Finish {toc}
+# Floor Finish System {toc}
−## Finish Type {toc}
+## Finish Application {toc}
+### The finish application shall be as indicated in the datasheet.
+
```datasheet
−label: Finish Type
+label: Finish Application
type: radio
−drawing_ref: true
options:
− - "Factory prefinished (aluminum-oxide UV-cured)"
− - "Site-finished (sealer and finish applied after installation)"
−default: "Factory prefinished (aluminum-oxide UV-cured)"
+ - "Factory finished"
+ - "Site finished"
+ - "Factory finished with a site applied final coat"
```
−### The finish type shall be specified as factory-prefinished or site-finished, and the choice shall be coordinated with the construction sequence and the other finish trades.
−### Site-finished flooring requires the floor to be clear of millwork toe-kicks, cabinetry, and traffic during sanding and finishing; specifying a site finish where casework is already installed creates a coordination conflict. {note}
−### The two finish approaches drive sharply different coordination. A factory-prefinished floor arrives with a tough, aluminum-oxide UV-cured finish already cured under factory conditions and is walkable as soon as it is installed, eliminating jobsite sanding dust, odor, and downtime, but its micro-beveled edges and fixed color are the price. A site-finished floor is installed raw and then sanded flat and sealed, stained, and finished in place, yielding a smooth monolithic surface and any custom color, but it adds days of dust- and odor-generating work that must be sequenced after the floor is clear of other trades and before the space is occupied. The decision belongs early in the finish narrative because it reshapes the whole closeout sequence. {note}
+### The finish application shall be coordinated with the construction sequence so that site finishing occurs after the floor area is clear of other trades and before the space is turned over.
+### The two approaches drive different schedules and produce different floors. A factory finish is cured under controlled conditions onto individual boards, arrives ready to walk on, and eliminates jobsite sanding dust, odor, and downtime, but it fixes the color and normally carries a micro-bevel at every board edge. A site finish is applied after the floor is sanded flat, producing a monolithic plane and any color the project wants, at the cost of several days of dust-generating and odor-generating work that has to be sequenced around every other finish trade. {note}
+### The decision belongs early because it reshapes closeout. Site finishing requires the floor to be clear of casework toe-kicks, millwork, and traffic during sanding and cure, so specifying it after casework is installed creates a sequencing conflict that has no good resolution on site. {note}
−## Factory Finish {toc}
+## Factory-Applied Finish {toc}
+### The factory-applied finish system shall be as indicated in the datasheet.
+
```datasheet
−label: Factory Finish Warranty (wear-through)
+label: Factory-Applied Finish System
type: select
−unit: years
options:
− - "10 years (residential)"
− - "15 years (light commercial)"
− - "25 years (commercial)"
− - "Lifetime (residential, limited)"
−default: "25 years (commercial)"
+ - "Ultraviolet cured urethane with aluminum oxide"
+ - "Ultraviolet cured urethane without aluminum oxide"
+ - "Ultraviolet cured hardwax oil"
+ - "Acrylic impregnated and irradiated wood"
+ - "Conversion varnish"
+default: "Ultraviolet cured urethane with aluminum oxide"
```
−### Factory-prefinished flooring shall carry an aluminum-oxide UV-cured finish with a manufacturer wear-through warranty appropriate to the commercial use.
−### The maintenance regime for a prefinished aluminum-oxide floor shall be obtained from the manufacturer, including the compatible recoat finish.
−### The maintenance regime and recoat compatibility information shall be captured in the closeout documents delivered at turnover.
−### A prefinished aluminum-oxide finish is extremely abrasion-resistant but cannot be recoated with ordinary oil-modified polyurethane — the new finish will not adhere to the cured aluminum-oxide surface without the manufacturer's prescribed abrasion and tie-coat procedure — so the closeout documents are the only reliable record of the correct recoat procedure once the floor is in service. {note}
+### The Contractor shall obtain from the flooring manufacturer and include in the maintenance data the recoat procedure and the finish product compatible with the delivered factory finish.
+### Damaged factory-finished boards shall be replaced rather than spot-finished, unless the flooring manufacturer publishes a repair procedure for the delivered finish and the repair matches the accepted mock-up or approved samples.
+### An aluminum-oxide ultraviolet-cured finish is among the most abrasion-resistant coatings available on wood, and the same cured hardness is why an ordinary polyurethane recoat will not bond to it. Recoating requires the manufacturer's prescribed abrasion and tie-coat procedure, which is why capturing that procedure in the closeout data is the only way the Owner can maintain the floor rather than replace it. {note}
+### Acrylic impregnation drives finish into the cell structure of the wood rather than laying a film on top of it, so the wear surface is the wood itself and abrasion does not expose a different-looking substrate; the tradeoff is that the color is fixed through the thickness and the material is refinished by a different process than a film finish. {note}
−## Site Finish System {toc}
+## Site-Applied Finish {toc}
+### The site-applied finish system shall be as indicated in the datasheet.
+
```datasheet
−label: Site Finish Type
+label: Site-Applied Finish System
type: select
−drawing_ref: true
options:
− - "Water-based urethane (low odor, fast recoat, color-stable)"
− - "Oil-modified urethane (amber tone, durable, slower cure)"
− - "Penetrating / hardwax oil (natural matte, spot-repairable)"
−default: "Water-based urethane (low odor, fast recoat, color-stable)"
+ - "Waterborne polyurethane, one component"
+ - "Waterborne polyurethane, two component"
+ - "Oil modified polyurethane"
+ - "Moisture cure urethane"
+ - "Acid cure conversion varnish"
+ - "Penetrating hardwax oil"
+ - "Penetrating tung or linseed oil"
+ - "Shellac sealer with a compatible topcoat"
```
```datasheet
−label: Finish Sheen
−type: radio
−drawing_ref: true
−options:
− - "Matte / low-luster (10-20 sheen units)"
− - "Satin (25-35 sheen units)"
− - "Semi-gloss (55-65 sheen units)"
−default: "Satin (25-35 sheen units)"
+label: Number of Site-Applied Finish Coats
+type: range
+min: 2
+max: 5
+step: 1
+setpoints: [2, 3, 4, 5]
+default: 3
```
+### Sanding shall progress through successively finer abrasive grits in accordance with the NWFA Sand and Finish Guidelines, and shall leave no drum marks, edger swirl, chatter, or dish-out visible under the permanent lighting.
+### The sealer and each finish coat shall be applied at the coverage rate and within the recoat window the finish manufacturer publishes for the site temperature and humidity at the time of application.
+### The Contractor shall provide continuous ventilation during application and cure as the finish manufacturer requires, and shall control dust in and adjacent to the work area.
+### The floor shall not receive traffic, coverings, or furniture until the finish has reached the cure the finish manufacturer requires for that exposure.
+### Finish systems differ in cure time, odor, color, and repairability rather than in quality. Waterborne polyurethane cures quickly with low odor and stays close to clear, which matters where the space turns over fast or where the design depends on the wood's natural color. Oil-modified polyurethane costs less and wears well but ambers progressively and cures slowly with strong solvent odor. Penetrating oils leave almost no film, so they show wear sooner and are maintained more often, and they are the only systems in the list that can be spot-repaired without recoating a whole area. {note}
+### Ambering is not a defect and it is not reversible. An oil-modified finish over white oak reads warm on the day it cures and warmer every year after, so where the approved sample was made matters: a sample coated months before installation has already begun the shift. {note}
+
+## Color and Sheen {toc}
+
+### The stain color shall be as indicated in the datasheet.
+
```datasheet
label: Stain Color
type: text
−drawing_ref: true
−default: "As selected by Architect from manufacturer's standard range, or natural (no stain)"
+drawing_ref: "the interior finish schedule"
+default: deferred
```
−### Site-finished flooring shall receive the specified sealer, stain (where a stain is specified), and finish system, applied in the number of coats and within the recoat windows the finish manufacturer requires.
−### Satin sheen is the common commercial and institutional default.
−### The finish system shall be selected for durability, color stability, odor and cure time, and maintainability appropriate to the occupancy.
−### The finish system is both a wear surface and an appearance choice. Water-based urethane cures fast, has low odor, stays color-stable, and is the common commercial choice where the space must be turned over quickly; oil-modified urethane is durable and inexpensive but ambers over time and cures slowly with strong solvent odor; penetrating and hardwax oils give a natural matte look and are spot-repairable but offer less film protection and need more frequent maintenance. Sheen is a trade-off with how readily the floor shows traffic and scratches: higher gloss reveals every scuff and footprint, which is why satin and matte dominate commercial work. {note}
+### The finish sheen shall be as indicated in the datasheet.
−# Special Conditions {toc}
+```datasheet
+label: Finish Sheen
+type: select
+options:
+ - "Matte"
+ - "Satin"
+ - "Semi-gloss"
+ - "Gloss"
+default: "Satin"
+```
−## Radiant Heat Compatibility {toc}
+### Stain shall be applied to a sanded sample of the specified species and grade and accepted in writing before stain is applied to the floor.
+### Sheen governs how readily the floor displays scuffs, footprints, and fine scratches: a gloss surface reflects specularly and shows every disturbance in the film, while matte and satin surfaces scatter the reflection and hide the same wear. That is a maintenance-visibility tradeoff rather than a durability one, since the film's abrasion resistance is set by its chemistry rather than its sheen. {note}
+### Stain behaves differently on different species and cuts. Dense, closed-grain species such as hard maple accept stain unevenly and blotch without a conditioner, while open-grain species such as oak take stain deeply and predictably, so a color approved on one species will not reproduce on another. {note}
+# Fire Performance {toc}
+
+## The floor covering system's critical radiant flux classification shall be as indicated in the datasheet.
+
```datasheet
−label: Radiant Floor Heating Present
+label: Floor Covering Critical Radiant Flux Class
+type: select
+derived: "the occupancy classification and the location of the floor within the means of egress under the adopted building code"
+options:
+ - "Class I, critical radiant flux of 0.45 W/cm² or greater"
+ - "Class II, critical radiant flux of 0.22 W/cm² or greater"
+ - "No critical radiant flux classification required at this location by the adopted building code"
+default: derived
+```
+
+## Where a critical radiant flux classification is required, the flooring system shall be tested as installed, including the adhesive, underlayment, and finish, in accordance with ASTM E648 or NFPA 253.
+## The Contractor shall submit the test report identifying the complete tested assembly, and a report covering a different underlayment, adhesive, or finish shall not be accepted as evidence for the specified assembly.
+## The adopted building code sets the classification by occupancy and by where the floor sits in the means of egress, and it treats traditional wood finish flooring applied directly to the floor or subfloor differently from manufactured floor coverings. The classification is therefore a code determination for a specific room in a specific building, not a property of the flooring product. {note}
+## Critical radiant flux is measured on the complete system because underlayment and adhesive change the result. A resilient acoustical underlayment beneath the same wood flooring can move a passing assembly into a failing one, which is why a report on the flooring alone proves nothing about the floor as built. {note}
+
+# Indoor Air Quality {toc}
+
+## The low-emitting materials requirement shall be as indicated in the datasheet.
+
+```datasheet
+label: Low-Emitting Materials Compliance
type: radio
−drawing_ref: true
options:
− - "No radiant heating"
− - "Yes - engineered flooring approved for radiant heat"
− - "Yes - solid flooring (narrow, species- and manufacturer-approved)"
−default: "No radiant heating"
+ - "Emissions testing to CDPH Standard Method v1.2 required for the flooring, adhesive, underlayment, and finish"
+ - "Emissions testing to CDPH Standard Method v1.2 required for the adhesive, underlayment, and finish"
+ - "No emissions testing required beyond the requirement of the Authority Having Jurisdiction"
```
+## The volatile organic compound content limit shall be as indicated in the datasheet.
+
```datasheet
−label: Maximum Floor Surface Temperature (radiant)
−type: range
−unit: °F
+label: Adhesive and Finish Volatile Organic Compound Content Limit
+type: radio
options:
− min: 80
− max: 85
− step: 1
−setpoints: [80, 85]
−default: 85
+ - "SCAQMD Rule 1168 for adhesives and Rule 1113 for coatings"
+ - "The volatile organic compound content limit of the Authority Having Jurisdiction"
+ - "No content limit beyond the requirement of the Authority Having Jurisdiction"
```
−### Where the flooring is installed over an in-floor radiant heating system, the flooring shall be a product the manufacturer approves in writing for radiant heat, and the radiant system shall be limited to a maximum floor surface temperature of 85 °F.
−### Solid flooring over radiant heat shall be limited to narrow widths (3 in or less) of a species and product the manufacturer approves for radiant service.
−### The radiant system shall be operated through a warm-up cycle before installation and the surface-temperature limit shall be maintained in service.
−### Radiant heat continuously drives moisture out of the underside of the wood, exaggerating the seasonal shrinkage that causes gapping; engineered flooring, being dimensionally stable, is generally preferred over solid for radiant applications, and where solid is used it must be narrow and species-approved. Exceeding the surface-temperature limit accelerates drying and can scorch the finish, so the limit is a service requirement, not just an installation note. {note}
+## Flooring containing a composite wood core shall be labeled as compliant with 40 CFR Part 770, and the Contractor shall retain the label documentation for the closeout record.
+## Emissions limits and content limits measure different things and are not substitutes for one another. A content limit caps the volatile organic compounds in the product as sold, which is an air-quality regulation aimed at outdoor ozone formation; an emissions limit caps what the installed product releases into the room over time, measured in a chamber. A product can satisfy one and fail the other. {note}
+## Wood flooring assemblies present three separate emission sources — the flooring itself, the adhesive, and the finish — and the adhesive and finish are applied wet in the occupied volume, which is why they carry the requirement even where the flooring is exempt. {note}
−## Expansion Provisions {toc}
+# Radiant Floor Heating {toc}
+## The Contractor shall confirm the extent of in-floor radiant heating indicated on [[drawing: the mechanical drawings]] before flooring is ordered.
+
```datasheet
−label: Perimeter Expansion Gap
+label: Maximum Floor Surface Temperature Over Radiant Heating
type: range
−unit: in
−drawing_ref: true
−options:
− min: 0.5
− max: 0.75
− step: 0.0625
−setpoints: [0.5, 0.75]
−default: 0.75
+unit: °F
+min: 75
+max: 85
+step: 1
+setpoints: [75, 80, 85]
+default: 80
```
−### A perimeter expansion gap shall be provided at all walls, doorframes, columns, thresholds, and fixed objects.
−### The perimeter expansion gap shall be sized to match or exceed the flooring manufacturer's requirement, and shall be never less than 3/4 in for 3/4-inch solid flooring or 1/2 in for engineered.
−### The expansion gap shall be concealed by the base, shoe, or threshold and shall never be filled rigidly or omitted.
−### Continuous runs of solid flooring exceeding the manufacturer's maximum unbroken length or width shall be interrupted by an expansion break (a T-molding or expansion joint) so the floor can move without buckling.
−### Wood expands and contracts across its width with the seasons, and a floor installed tight to the walls in a continuous large area with no room to grow will swell and buckle in humid weather, lifting off the substrate. The perimeter gap and, in large areas, an intermediate expansion break give the floor the room it must have; omitting or undersizing them is among the most common and most destructive errors. {note}
+## Flooring installed over a radiant heating system shall be a product the flooring manufacturer approves in writing for radiant service.
+## The radiant heating system shall be operated through the warm-up and dry-out cycle the radiant system manufacturer publishes before flooring is delivered.
+## The radiant heating system shall be controlled by a floor sensor limiting the floor surface temperature to the value indicated in the datasheet, in service as well as during installation.
+## The adhesive used over a radiant heated slab shall be rated by its manufacturer for continuous service at the specified maximum floor surface temperature.
+## The radiant heating system, its controls, and its floor sensor are specified under [[sync/radiant-heating-and-cooling-panels]].
+## Radiant heat drives moisture out of the underside of the wood continuously, so the floor sits at a lower equilibrium moisture content during the heating season than the room air alone would produce, and the seasonal shrinkage that causes gapping is correspondingly larger. Dimensionally stable constructions and narrower face widths reduce that movement, and a quartersawn or rift cut reduces it further. {note}
+## The surface temperature limit is a service requirement, not just an installation instruction. Exceeding it accelerates the drying, can check the wood, and can soften or discolor the finish, and none of that is visible until after the first heating season. {note}
−## Gymnasium Sports Floors {toc}
+# Maple Sports Flooring {toc}
+## Requirements in this article apply where the flooring construction and the room use indicated in the Contract Documents call for a maple sports floor.
+## The sports floor system type shall be as indicated in the datasheet.
+
```datasheet
label: Sports Floor System Type
type: select
−drawing_ref: true
options:
− - "Anchored resilient (sleeper or channel system, fixed to slab)"
− - "Floating resilient (pad-and-sleeper or panel system)"
− - "Portable / panel sports floor"
−default: "Floating resilient (pad-and-sleeper or panel system)"
+ - "Anchored resilient sleeper system"
+ - "Anchored resilient steel channel system"
+ - "Free floating sleeper system"
+ - "Free floating panel subfloor system"
+ - "Fixed sleeper system without resilient pads"
+ - "Encapsulated resilient pad system"
+ - "Portable cushioned panel system"
```
+## The athletic performance class shall be as indicated in the datasheet.
+
```datasheet
label: ASTM F2772 Athletic Performance Class
−type: radio
−drawing_ref: true
+type: select
options:
− - "Class 1 (entry athletic performance)"
+ - "Class 1"
- "Class 2"
- "Class 3"
− - "Class 4 (highest force reduction / area deflection)"
−default: "Class 3"
+ - "Class 4"
```
−### Gymnasium and multipurpose sports floors shall be northern hard maple graded under the MFMA rules.
−### Gymnasium and multipurpose sports floors shall be installed as a complete resilient sleeper-and-pad system.
−### Gymnasium and multipurpose sports floors shall meet the specified ASTM F2772 athletic performance class for force reduction, ball rebound, area deflection, and surface friction.
−### The sports floor system, its resilient pads, the game-line layout, and the surface finish shall be furnished as a coordinated system from a single manufacturer.
−### Game lines and logos shall be applied per the governing athletic body's layout and within the floor finish system so they wear with the floor.
−### A gymnasium maple floor is an engineered athletic system, not just a wood surface: the resilient pads and sprung sleepers give the floor the controlled deflection and shock absorption that protect athletes, and ASTM F2772 grades that performance into classes. Specifying MFMA-certified maple without an ASTM F2772 performance class lets a substandard sleeper system satisfy the letter of the specification while failing the athletic performance the floor exists to provide. {note}
+## Sports flooring shall be northern hard maple graded under the MFMA Grading Rules.
+## The sports floor system shall meet the specified ASTM F2772 class for force reduction, vertical deformation, ball rebound, area of deflection, and surface friction.
+## The flooring, resilient elements, subfloor components, vents, base, and finish shall be furnished as a coordinated system by a single manufacturer.
+## Game lines and logos shall be laid out as indicated on [[drawing: the gymnasium floor plan]].
+## Game lines and logos shall be applied within the finish system so that they wear with the floor rather than on top of it.
+## The perimeter ventilating base shall be installed continuously and shall not be sealed, caulked, or blocked.
+## A sports floor is an engineered athletic assembly rather than a wood surface over a subfloor. The resilient elements give the floor the controlled deflection that reduces impact loading on athletes, and ASTM F2772 grades that behavior into classes against measured criteria. Specifying MFMA maple without a performance class permits an assembly that satisfies the material requirement while delivering none of the athletic performance the floor exists to provide. {note}
+## The classes describe different balances rather than a quality ladder. A higher class delivers more force reduction and area deflection, which favors impact sports; a multipurpose room that also carries staging, chairs, and rolling loads may be specified at a lower class deliberately, because the same deflection that protects an athlete is a liability under a point load. {note}
+## The ventilating base is part of the assembly's moisture strategy, not trim. It lets the air space beneath a floating or sleeper system exchange with the room, and sealing it converts the cavity into an unventilated space directly over a slab. {note}
−## Reclaimed and Salvaged Wood {toc}
+# Reclaimed and Salvaged Flooring {toc}
−### Where reclaimed or salvaged wood flooring is specified, the Contractor shall submit the source, the remilling and re-grading basis, the kiln-dried moisture content, and evidence that the material is free of embedded metal, insects, and contaminants, and shall acclimate and test it as for new flooring.
−### The moisture content of reclaimed flooring shall be verified by meter before acclimation begins, because salvaged material arrives at an unknown equilibrium that may differ substantially from kiln-dried new product.
−### Reclaimed flooring is within the scope of this standard but the standard NWFA/NOFMA grading rules do not apply directly to it; the NWFA's separate reclaimed-wood guidance and the project-specific grade defined in the submittal govern its appearance, and moisture verification is especially important because the material's equilibration history is unknown. {note}
+## Requirements in this article apply where the Contract Documents specify reclaimed or salvaged wood flooring.
+## The Contractor shall submit the source of the material, the remilling and regrading basis, the kiln-drying record, and the project-specific grade definition.
+## Reclaimed material shall be kiln dried after remilling and shall be certified free of insects and active infestation.
+## Reclaimed material shall be scanned for embedded metal and shall be free of nails, screws, and other fasteners before it is delivered to the site.
+## The Contractor shall measure and record the moisture content of reclaimed material on delivery, before acclimation begins.
+## Reclaimed material shall be acclimated, tested, and installed under the same moisture criteria as new flooring.
+## The standard grading rules do not apply to reclaimed material, so the grade is whatever the approved submittal defines: the character marks, nail holes, saw marks, checks, and color variation that are the reason to specify it are also, under any conventional rule, defects. Defining the accepted range in the submittal is what makes the material inspectable. {note}
+## Salvaged material arrives at an unknown equilibrium set by wherever it spent the last several decades, which can be far from a conditioned interior in either direction, so the delivery reading is the one that tells the installer how much acclimation the lot actually needs. {note}
+# Transitions and Accessories {toc}
+
+## The transition and reducer material shall be as indicated in the datasheet.
+
+```datasheet
+label: Transition and Reducer Material
+type: select
+options:
+ - "Wood matching the flooring, factory finished"
+ - "Wood matching the flooring, site finished"
+ - "Extruded aluminum transition profile"
+ - "Extruded brass or bronze transition profile"
+ - "Rubber or vinyl transition profile"
+ - "Stone or solid surface threshold"
+```
+
+## Transitions shall be provided at every change in floor finish, at every change in finish floor elevation, and at every doorway where the flooring stops.
+## Transitions between finishes of different thickness shall be sloped or ramped so that no abrupt vertical change exceeding 1/4 in remains, and any change between 1/4 in and 1/2 in shall be beveled at a slope no steeper than 1 unit vertical in 2 units horizontal.
+## Transition profiles shall be fastened to the substrate rather than to the wood flooring, so that the flooring remains free to move beneath them.
+## Base and shoe shall be fastened to the wall rather than to the flooring.
+## A transition or base fastened through the wood flooring pins the floor at that point and defeats the expansion allowance the perimeter detail provides, which is why the fastening substrate matters as much as the profile. {note}
+## The vertical change limits are accessibility requirements from the adopted code rather than flooring preferences, and they govern the transition detail at every doorway regardless of what the two finishes are. {note}
+
# Installation {toc}
## Layout and Substrate Acceptance {toc}
−### The Contractor shall not begin installation until the substrate is prepared to the required flatness, the documented moisture tests confirm the substrate and wood are within the governing limits or the specified mitigation is installed, the acclimation is verified by meter, and the ambient conditions are within range.
−### Layout shall establish a straight, square starting line and balance the board courses so that the field is symmetrical and no excessively narrow ripped course occurs at a wall, following the [[drawing: finish plan]] for direction and any feature or border pattern.
−### Acceptance of the substrate is the Contractor's responsibility; installing wood flooring over a substrate that is out of tolerance, too wet, or untested transfers a known defect into the finished floor, and the resulting failure is not a product defect and is not covered by the warranty. {note}
+### The Contractor shall inspect and accept the substrate in writing before installation begins.
+### The Contractor shall not begin installation until the substrate flatness, the documented moisture test results, the verified acclimation readings, and the interior ambient conditions all satisfy this standard, or until the specified moisture control measure is installed and verified.
+### The Contractor shall establish a straight, square starting line referenced to the room geometry rather than to a single wall.
+### Layout shall balance the courses so that no ripped course at a wall is narrower than half the specified face width.
+### The direction of the flooring, borders, feature strips, and pattern layouts shall be as indicated on [[drawing: the floor finish plans]].
+### Accepting a substrate that is out of tolerance, wet, or untested transfers a known defect into the finished floor. The resulting failure is not a product defect, is not covered by the flooring manufacturer's warranty, and is charged to the party that accepted the substrate. {note}
−## Installation Execution {toc}
+## Installation of Fastened Flooring {toc}
−### Flooring shall be installed with end joints staggered and racked for a random distribution of board lengths and a natural blend of the grade's color and grain range.
−### Nail- and staple-down flooring shall be fastened on the specified schedule, blind-nailed through the tongue, with the first and last courses face-nailed or top-nailed and the holes filled where the manufacturer directs.
−### Glue-down flooring shall be set into wet adhesive within the adhesive's working time, fully bedded, and rolled or weighted as the adhesive manufacturer requires to achieve full transfer.
−### Floating flooring shall be installed over the specified underlayment with edge joints glued or clicked per the profile and with the perimeter gap maintained continuously.
−### Racking the floor from several open cartons at once blends the natural color and grain variation across the field; installing carton by carton concentrates variation into visible patches that read as a defect even when every board is within grade. {note}
+### Flooring shall be racked from not fewer than three open cartons or bundles at a time so that color, grain, and length distribute across the field.
+### End joints in adjacent courses shall be staggered not less than 6 in, and a repeating stagger pattern shall not be used.
+### Flooring shall be blind nailed through the tongue at the angle the fastening tool and the flooring manufacturer require.
+### The first and last courses and any course too close to a wall for a fastening tool shall be face fastened, and the fastener holes shall be filled with a filler matching the finished floor.
+### Boards with defects outside the specified grade shall be culled rather than installed, and the Contractor shall order material with an allowance for culling and waste.
+### Racking from several open cartons blends the natural variation across the whole floor. Installing carton by carton concentrates each production run into a visible band, which reads as a defect even when every board is within grade and the mill did nothing wrong. {note}
−## Protection During Construction {toc}
+## Installation of Bonded Flooring {toc}
−### After installation, the floor shall be protected from traffic, point loads, spills, and other trades with a breathable protective covering until turnover, and site-finished floors shall be protected only after the finish has reached the cure the manufacturer requires.
−### A non-breathable plastic film shall not be laid directly over a newly site-finished floor.
−### A newly site-finished floor continues to cure and off-gas for days; sealing it under non-breathable plastic traps solvent and moisture against the finish and causes it to cloud or fail to harden, so any covering placed over a fresh finish must be breathable. {note}
+### Adhesive shall be applied only to a substrate that is clean, dry, structurally sound, and free of curing compound, sealer, paint, dust, and bond breakers.
+### Flooring shall be set into the adhesive and worked into full contact, and boards shall not be slid through the adhesive in a way that displaces it from the substrate.
+### The installed floor shall be rolled or weighted within the adhesive's published open time where the adhesive manufacturer requires it.
+### Straps, tape, or weights used to hold boards in position during cure shall be removed without damaging the finish, and any residue shall be removed with the cleaner the flooring manufacturer specifies.
+### Working the board into the wet adhesive rather than sliding it is what produces the transfer the bond depends on; a board slid into place plows the adhesive ahead of it and leaves ridges with voids between them, which is what a hollow-sounding floor is. {note}
−# Field Inspection {toc}
+## Installation of Floating Flooring {toc}
−## Moisture and Acclimation Verification {toc}
+### The underlayment shall be installed continuously, with joints butted or lapped as its manufacturer directs, and shall not be doubled except where its manufacturer permits it.
+### Edge joints shall be glued or engaged as the joinery system requires, with adhesive applied in the position and quantity the flooring manufacturer specifies.
+### The perimeter expansion space shall be maintained continuously around the entire field, including at pipes, columns, door frames, and transitions.
+### The floor shall not be pinned by cabinetry, fixed equipment, or fasteners set through the flooring into the substrate.
+### The perimeter space is the only place a floating floor can put its movement, so a single restraint anywhere around the field transfers the whole floor's expansion to the remaining edges and produces a peaked or buckled floor away from the restraint. {note}
−### The Contractor shall record and retain the substrate moisture readings, the wood moisture content, the acclimation period and conditions, and the ambient temperature and relative humidity at installation as the documented basis for the warranty.
−### Where concrete-slab mitigation was installed, the Contractor shall verify it was rated for the relative humidity actually measured.
+## Protection {toc}
−## Visual and Performance Inspection {toc}
+### The Contractor shall protect the completed floor from traffic, point loads, spills, and other trades until the flooring work is accepted.
+### Protective covering shall be vapor permeable and shall be a product the flooring and finish manufacturers approve.
+### Protective covering shall not be applied over a site-applied finish until the finish has reached the cure its manufacturer requires for covering.
+### Protective covering shall not be taped to the finished floor surface.
+### Rolling loads and equipment shall be moved over the floor on protective panels rather than directly on the covering.
+### A newly applied site finish continues to cure and release solvent for days after it is walkable. Sealing it under a non-breathable film traps that solvent and moisture against the film, which clouds the finish, prevents it from reaching full hardness, and can lift it entirely. {note}
+### Tape adhesive left on a cured finish can pull the film when it is removed and can discolor the finish where it sat, which is why the covering is held down at its edges away from the wood rather than on it. {note}
−### After installation and, for site-finished work, after the finish has cured, the floor shall be inspected under permanent or equivalent lighting for cupping, crowning, gapping, hollow or loose boards, squeaks, finish uniformity and sheen, color and grain blend, board-end and edge tightness, expansion-gap continuity, and transition quality.
−### Hollow, loose, or squeaking boards shall be corrected by re-fastening, re-bonding, or replacement, and the cause investigated where the condition is widespread.
−### For gymnasium sports floors, the installed system shall be verified against the specified ASTM F2772 performance class before acceptance.
+# Field Quality Control {toc}
−# Cleaning and Initial Maintenance {toc}
+## The Contractor shall record and retain the final substrate moisture readings, the flooring moisture content, the acclimation period and conditions, and the interior temperature and relative humidity at installation.
+## Where a moisture control measure was installed, the Contractor shall verify and record that the product used is rated for the substrate condition actually measured.
+## After installation, and for site-finished work after the finish has cured, the floor shall be inspected under the permanent lighting or equivalent temporary lighting at the same intensity and position.
+## The inspection shall cover cupping, crowning, gapping, overwood, hollow or loose boards, squeaks, finish uniformity and sheen, color and grain distribution, board end and edge tightness, continuity of the perimeter expansion space, and transition quality.
+## Hollow, loose, or squeaking boards shall be corrected by refastening, rebonding, or replacement.
+## Where the condition is present in more than 2% of the floor area, the Contractor shall investigate and report the cause before making repairs.
+## Sports flooring shall be verified against the specified ASTM F2772 class before acceptance, by field test where the Contract Documents require one.
+## The Contractor shall bear the cost of retesting and reinspection following a failed test or a rejected area.
+## Where the parties disagree whether an observed condition is a defect or is within the natural range of the accepted samples and mock-up, the Architect of Record shall make the initial determination.
+## Inspecting under the permanent lighting is not a formality. Grazing light from a wall wash or a low winter sun reveals sanding marks, overwood, and mild cupping that overhead temporary lighting hides completely, and a floor accepted under work lights is routinely rejected the week the permanent fixtures are energized. {note}
+## Cupping and crowning both indicate a moisture gradient through the board rather than a manufacturing defect: cupping means the underside is wetter than the face, crowning the reverse. Sanding a cupped floor flat before the gradient equalizes converts a temporary condition into a permanent one. {note}
−## After installation and finish cure, the floor shall be cleaned of construction soil using only the cleaning method and products the flooring and finish manufacturers approve, and protected from heavy traffic until turnover.
−## The Contractor shall furnish the Owner with the manufacturer's maintenance program, identifying approved cleaning agents, the recoat or refinish procedure and compatible finish, and the interior humidity band the floor must be kept within to remain stable.
−## Wood floors are damaged by standing water and by cleaners not formulated for wood finishes; a wet-mopping or steam-cleaning regime intended for resilient or tile floors will dull, swell, or delaminate a wood floor, which is why the approved-products maintenance program is part of the deliverable. {note}
+# Cleaning and Owner Maintenance {toc}
+## After the finish has cured, the Contractor shall clean the floor of construction soil using only the method and products the flooring and finish manufacturers approve.
+## The Contractor shall furnish the Owner with the manufacturer's written maintenance program identifying approved cleaning agents and methods, the recoat and refinish procedure with the compatible finish product, the recommended maintenance interval, and the interior temperature and relative humidity range the floor is to be held within.
+## The Contractor shall demonstrate the routine cleaning procedure to the Owner's maintenance personnel before turnover.
+## Walk-off matting at exterior entrances is specified under [[sync/entrance-flooring]].
+## Wood floors are damaged by standing water and by cleaners formulated for other floor types. A wet-mopping or steam-cleaning regime appropriate to resilient or tile flooring drives water into the board joints, dulls or clouds the finish, and over time swells the edges or delaminates an engineered face, which is why the approved-products list is part of the deliverable rather than advice. {note}
+## Most of the wear a wood floor takes is abrasive grit tracked in from outside, so entrance matting and a routine dry-cleaning schedule do more to extend the interval between recoats than any property of the finish itself. {note}
+
# Delivery, Storage, and Handling {toc}
−## Wood flooring, adhesives, and accessories shall be delivered in the manufacturer's original sealed packaging with grade, species, and lot information intact, and shall not be delivered to the project until the building is enclosed, conditioned, and within the acclimation temperature and humidity range.
−## Flooring shall be stored flat, off the floor, in the conditioned space where it will be installed, protected from moisture, direct sun, and physical damage, and broken out or cross-stacked for acclimation as the manufacturer directs.
−## Adhesives and water- or solvent-based finishes shall be stored within their temperature range, protected from freezing, and handled per the safety data sheet.
−## Delivering wood flooring to an unconditioned or unenclosed building defeats acclimation before it begins: the wood equalizes to the wrong moisture content, and no amount of jobsite time afterward corrects a floor that was wetted on a damp slab or dried in an overheated shell during storage. {note}
+## Flooring, adhesives, underlayment, and accessories shall be delivered in the manufacturer's original packaging with grade, species, lot, and production run identification intact.
+## Flooring shall not be delivered to the site until the building is enclosed and weathertight, the permanent conditioning is operating, and the interior is within the specified temperature and relative humidity range.
+## Flooring shall be stored flat and off the substrate, in the conditioned space in which it will be installed, protected from direct sunlight, moisture, and physical damage.
+## Flooring shall be broken out, opened, or cross-stacked for acclimation as the flooring manufacturer directs.
+## Material from different lots or production runs shall be identified and, where color varies between them, distributed across the floor rather than concentrated in one area.
+## Adhesives and finishes shall be stored within the temperature range their manufacturers specify, protected from freezing, and handled in accordance with the safety data sheet.
+## Adhesives and finishes past their published shelf life shall not be used.
+## The Contractor shall bear the cost of material damaged by storage in conditions outside those specified.
+## Delivering flooring into an unenclosed or unconditioned building defeats acclimation before it starts: the wood equalizes to the wrong climate, and no amount of subsequent jobsite time corrects a lot that absorbed moisture standing on a damp slab or dried out in an overheated shell. {note}
# Warranty {toc}
+## The manufacturer product warranty period shall be as indicated in the datasheet.
+
```datasheet
−label: Manufacturer Product Warranty
−type: select
+label: Manufacturer Product Warranty Period
+type: range
unit: years
−options:
− - "1 year (material defects only)"
− - "5 years (commercial wear / structural)"
− - "10 years (commercial)"
− - "25 years (prefinished commercial wear-through)"
−default: "10 years (commercial)"
+min: 1
+max: 50
+step: 1
+setpoints: [1, 5, 10, 15, 20, 25, 30, 50]
```
+## The factory finish wear-through warranty period shall be as indicated in the datasheet.
+
```datasheet
−label: Installation Workmanship Warranty
−type: select
−options:
− - "1 year from substantial completion"
− - "2 years from substantial completion"
−default: "1 year from substantial completion"
+label: Factory Finish Wear-Through Warranty Period
+type: range
+unit: years
+min: 1
+max: 30
+step: 1
+setpoints: [1, 3, 5, 10, 15, 20, 25, 30]
```
−## The flooring manufacturer shall warrant the material against manufacturing and grading defects and, for prefinished product, against finish wear-through for the period stated.
−## The Contractor shall warrant the installation — including substrate preparation, moisture control, acclimation, attachment, expansion provisions, site finish, and transitions — against defective workmanship for the project warranty period.
−## The moisture and acclimation records are part of the warranty basis and shall be retained and delivered.
−## Most manufacturer warranties are void unless the substrate moisture was within the stated limit and the wood was acclimated and installed at the correct moisture content, both documented at the time of installation. Failures arising from operating the building outside the specified humidity band, from water intrusion, or from maintenance contrary to the manufacturer's instructions are excluded from both warranties. {note}
+## The installation workmanship warranty period shall be as indicated in the datasheet.
+```datasheet
+label: Installation Workmanship Warranty Period
+type: range
+unit: years
+min: 1
+max: 5
+step: 1
+setpoints: [1, 2, 3, 5]
+default: 1
+```
+
+## The flooring manufacturer shall warrant the material against manufacturing, milling, and grading defects for the specified period from the date of Substantial Completion.
+## The Contractor shall warrant the installation, including substrate preparation, moisture control, acclimation, attachment, expansion provisions, site-applied finish, and transitions, for the specified period from the date of Substantial Completion.
+## Warranties shall be issued in the Owner's name and shall be transferable to a subsequent owner of the building.
+## The Contractor shall bear the cost of removing and replacing other work that has to be disturbed to reach a warranted repair, and shall bear the cost of repairing collateral damage caused by the repair work.
+## Work repaired or replaced under warranty shall carry a new warranty of the full original period from the date of the repair, or the remainder of the original period, whichever is longer.
+## The Contractor shall retain the moisture and acclimation record for the duration of the warranty period and shall furnish it on request.
+## Most manufacturer warranties are conditioned on the substrate having been within the stated moisture limit and the wood having been installed at the correct moisture content, both documented at the time of installation, which is why the moisture record is the operative document in a claim rather than supporting paperwork. {note}
+## Both warranties conventionally exclude damage arising from operating the building outside the specified temperature and humidity range, from water intrusion or plumbing failure, from abrasive or point-load damage, and from maintenance contrary to the manufacturer's written instructions. {note}
+
# Spare and Extra Materials {toc}
+## The attic stock quantity shall be as indicated in the datasheet.
+
```datasheet
−label: Attic Stock Delivered to Owner
−type: radio
−options:
− - "Yes - sealed flooring and touch-up/finish material for each type and color"
− - "No"
−default: "Yes - sealed flooring and touch-up/finish material for each type and color"
+label: Attic Stock Quantity
+type: range
+unit: '% of installed area'
+min: 0
+max: 10
+step: 0.5
+setpoints: [0, 1, 2, 3, 5, 10]
```
−## The Contractor shall deliver to the Owner sealed attic stock of each flooring type, species, grade, and color installed, together with touch-up and, for site-finished floors, matching finish material, in a quantity sufficient for localized repair and labeled with the species, grade, color, and lot information.
−## Because wood color and grain vary over production runs and a later finish ambers with age, attic stock from the original lot is the only reliable way to make an inconspicuous repair; replacement material bought years later will rarely match the installed floor's color and patina. {note}
+## The Contractor shall deliver attic stock of each flooring construction, species, grade, dimension, and color installed, drawn from the same production lots as the installed material.
+## The Contractor shall deliver touch-up material and, for site-finished floors, matching stain and finish material sufficient for localized repair.
+## Attic stock shall be packaged, sealed, and labeled with the species, construction, grade, dimensions, color, finish, and production lot, and shall be stored where the Owner directs.
+## Wood color and grain vary between production runs, and a cured finish continues to shift in color with age and light exposure. Material from the original lot is the only stock that can produce an inconspicuous repair; flooring purchased years later will match the specification and not the floor. {note}