1 Scope

NOTE This standard governs interior wood finish flooring together with the substrate preparation, moisture control, attachment, and finish work that make it perform. (1.1)

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. (1.2)

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. (1.3)

NOTE The product families within this scope are the following: (1.4)

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

NOTE The following are outside this standard: (1.5)

Resilient wood-look flooring, including luxury vinyl plank, vinyl composition tile, and linoleum, specified under Resilient FlooringResilient FlooringResolves to the current edition.sync/resilient-flooring
Carpet and carpet tile, specified under CarpetCarpetResolves to the current edition.sync/carpet
Ceramic, porcelain, and natural stone tile, specified under Ceramic TileCeramic TileResolves to the current edition.sync/ceramic-tile and Natural Stone TileNatural Stone TileResolves to the current edition.sync/natural-stone-tile
Polished, ground, and sealed bare concrete, specified under Polished ConcretePolished Concrete FlooringResolves to the current edition.sync/polished-concrete
Poured and precast terrazzo, specified under TerrazzoTerrazzoResolves to the current edition.sync/terrazzo
Resinous and epoxy floor coatings, specified under Resinous FlooringResinous FlooringResolves to the current edition.sync/resinous-flooring and Epoxy FlooringEpoxy Floor CoatingsResolves to the current edition.sync/epoxy-flooring
Walk-off matting and entrance flooring, specified under Entrance FlooringEntrance Flooring and Walk-Off SystemsResolves to the current edition.sync/entrance-flooring
Raised access floor systems, specified under Raised Access FlooringRaised Access FlooringResolves to the current edition.sync/raised-access-flooring
Structural framing, sheathing, and subfloor panels, specified under Wood FramingWood Light FramingResolves to the current edition.sync/wood-framing and Wood SheathingWood Structural Panel SheathingResolves to the current edition.sync/wood-sheathing
Wood base, shoe, thresholds, and running trim, specified under Architectural Wood Trim And PanelingArchitectural Wood Trim and PanelingResolves to the current edition.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

1.6 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.

1.7 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.

1.8 The concrete substrate, its curing and sealing method, and its under-slab vapor retarder shall be as specified in Cast In Place ConcreteCast-in-Place ConcreteResolves to the current edition.sync/cast-in-place-concrete, Concrete Curing And FinishingConcrete Curing and FinishingResolves to the current edition.sync/concrete-curing-and-finishing, Slab On GradeSlab-on-GradeResolves to the current edition.sync/slab-on-grade, and Vapor Barriers Under SlabUnder-Slab Vapor BarriersResolves to the current edition.sync/vapor-barriers-under-slab.

1.9 Patching and leveling of the substrate shall use products specified in Cementitious Self Leveling UnderlaymentCementitious Self-Leveling UnderlaymentResolves to the current edition.sync/cementitious-self-leveling-underlayment and approved in writing by the flooring and adhesive manufacturers.

1.10 Finish floor elevations and transitions at every boundary between wood flooring and an adjacent floor finish shall be as detailed on the interior finish details.

NOTE 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. (1.11)

2 Referenced Standards

Standard	Title
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 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

2.1 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.

2.2 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.

2.3 The Contractor shall install the flooring in accordance with the flooring manufacturer's written installation instructions in addition to this standard.

NOTE 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. (2.4)

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. (2.5)

3 Submittals

3.1 Action Submittals

3.1.1 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 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

Action Submittals Requiredcheckbox

☐ 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

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. (3.1.2)

3.2 Informational Submittals

3.2.1 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

Informational Submittals Requiredcheckbox

☐ 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

3.2.2 Installation shall not begin until the substrate moisture test reports have been submitted and reviewed by the Architect of Record.

NOTE 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. (3.2.3)

3.3 Closeout Submittals

3.3.1 The Contractor shall submit the following at Substantial Completion:

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

Closeout Submittals Requiredcheckbox

☐ 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

NOTE 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. (3.3.2)

4 Quality Assurance

4.1 Installer Qualifications

4.1.1 The installing firm shall hold the qualification indicated in the datasheet.

Installer Qualificationselect

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

4.1.2 The installing firm shall assign a single on-site foreman who is present for the duration of the flooring work.

4.1.3 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.

NOTE 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. (4.1.4)

4.2 Mock-Up

4.2.1 The requirement for a mock-up shall be as indicated in the datasheet.

Mock-Up Requiredradio

○ Mock-up required

● Mock-up not required

4.2.2 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.

4.2.3 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.

4.2.4 The mock-up shall be reviewed and accepted in writing by the Architect of Record before the balance of the flooring work begins.

4.2.5 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.

4.2.6 The mock-up shall remain in place and undisturbed until the flooring work is accepted.

4.2.7 Where the parties disagree whether installed flooring matches the accepted mock-up, the Architect of Record shall make the initial determination.

NOTE 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. (4.2.8)

4.3 Pre-Installation Conference

4.3.1 The Contractor shall convene a pre-installation conference not less than ten business days before flooring is delivered to the site.

4.3.2 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.

4.3.3 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.

4.3.4 The Contractor shall record the conference and distribute the report to all attendees within five business days.

NOTE 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. (4.3.5)

5 Interior Climate and Acclimation

5.1 In-Service Interior Climate

5.1.1 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.

In-Service Interior Temperaturerange

°F

55606570758085

In-Service Interior Relative Humidity, Minimumrange

% RH

15202530354045

In-Service Interior Relative Humidity, Maximumrange

% RH

40455055606570

5.1.2 The specified temperature and relative humidity ranges shall be maintained continuously from the date of delivery through acclimation, installation, finishing, and Owner occupancy.

5.1.3 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.

5.1.4 The specified in-service relative humidity range shall be one the building's mechanical systems can hold year round for Climate ZoneClimate ZoneParameterEach project supplies its own value.climate-zone.

5.1.5 Where the mechanical systems cannot hold the specified range year round for Climate ZoneClimate ZoneParameterEach project supplies its own value.climate-zone without supplemental humidification or dehumidification, the Contractor shall report the condition to the Architect of Record in writing before flooring is ordered.

NOTE 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. (5.1.6)

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. (5.1.7)

5.2 Wood Acclimation

5.2.1 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.

Minimum Acclimation Periodrange

days

357101421

5.2.2 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.

5.2.3 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.

5.2.4 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.

NOTE 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. (5.2.5)

NOTE Acclimating material inside sealed packaging accomplishes nothing, because the wrap is what stops the exchange the process depends on. (5.2.6)

5.3 Wood Moisture Content at Installation

5.3.1 The moisture content of the flooring at the time of installation shall be within the range indicated in the datasheet.

Flooring Moisture Content at Installation, Minimumrange

%

4567891011

Derived — the equilibrium moisture content corresponding to the specified in-service interior temperature and relative humidity

Flooring Moisture Content at Installation, Maximumrange

%

67891011121314

Derived — the equilibrium moisture content corresponding to the specified in-service interior temperature and relative humidity

Maximum Flooring-to-Substrate Moisture Content Differentialrange

percentage points

12345

Derived — the specified face width, per the differential limits of the NWFA Installation Guidelines

5.3.2 The moisture content differential between solid strip flooring narrower than 3 in and the wood substrate shall not exceed 4 percentage points.

5.3.3 The moisture content differential between solid flooring 3 in and wider and the wood substrate shall not exceed 2 percentage points.

5.3.4 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.

NOTE 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. (5.3.5)

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. (5.3.6)

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. (5.3.7)

6 Substrate Moisture Testing and Control

6.1 Concrete Slab Moisture Testing

6.1.1 Concrete slabs shall be tested for internal relative humidity in accordance with ASTM F2170 before flooring, adhesive, or moisture control material is ordered.

Maximum Slab Internal Relative Humidity, ASTM F2170range

% RH

6065707580859095100

Maximum Moisture Vapor Emission Rate, ASTM F1869range

lb/1000 ft²/24 h

12345710

Maximum Slab Surface pHrange

789101112

6.1.2 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.

6.1.3 Probes shall be allowed to equilibrate for the period ASTM F2170 requires before a reading is recorded.

6.1.4 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.

6.1.5 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.

6.1.6 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.

6.1.7 The slab surface pH shall be tested in accordance with ASTM F710 at the same frequency as the relative humidity testing.

6.1.8 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.

6.1.9 Slabs on grade and below grade shall be confirmed to be above Seasonal High Groundwater ElevationSeasonal High Groundwater ElevationParameterEach project supplies its own value.seasonal-high-groundwater-elevation before wood flooring is installed.

6.1.10 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.

NOTE 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. (6.1.11)

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. (6.1.12)

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. (6.1.13)

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. (6.1.14)

6.2 Wood Substrate Moisture

6.2.1 Wood substrates shall be tested for moisture content before flooring is delivered and again immediately before installation.

Maximum Wood Substrate Moisture Contentrange

%

891011121314

6.2.2 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.

6.2.3 Crawl spaces beneath a wood substrate shall be ventilated or conditioned and shall have a ground vapor retarder installed before flooring is delivered.

6.2.4 Where the wood substrate exceeds the specified moisture content, the Contractor shall identify and correct the moisture source before installing flooring.

NOTE 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. (6.2.5)

6.3 Moisture Control Measures

6.3.1 The moisture control measure shall be as indicated in the datasheet.

Moisture Control Measureselect

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

Derived — the measured slab internal relative humidity and the moisture limits published for the specified flooring and adhesive (by default)

6.3.2 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.

6.3.3 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.

6.3.4 The adhesive used over a topical moisture control membrane shall be a product the membrane manufacturer approves in writing for use over that membrane.

6.3.5 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.

NOTE 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. (6.3.6)

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. (6.3.7)

7 Flooring Construction and Format

7.1 The flooring construction shall be as indicated in the datasheet.

Flooring Constructionselect

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

7.2 The board format shall be as indicated in the datasheet.

Board Formatselect

Strip

Plank

Mixed-width plank

Parquet tile

Parquet block

Herringbone

Chevron

Feature border with field

7.3 Solid sawn flooring shall not be bonded directly to a concrete slab on or below grade.

7.4 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.

7.5 Engineered flooring containing a composite wood core shall comply with the formaldehyde emission standards of 40 CFR Part 770.

7.6 End-grain block flooring shall be specified with the block height, the treatment or impregnation, and the setting bed identified in the submittal.

7.7 The extent of each flooring construction and format shall be as indicated on the room finish schedule.

NOTE 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. (7.8)

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. (7.9)

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. (7.10)

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. (7.11)

8 Species, Cut, and Grade

8.1 Species

8.1.1 The wood species shall be as indicated in the datasheet.

Wood Speciesselect

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)

8.1.2 Imported and tropical species shall be identified by botanical name in addition to any common or trade name.

8.1.3 The Contractor shall submit chain-of-custody or legal-harvest documentation for imported species where the Contract Documents require it.

NOTE 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. (8.1.4)

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. (8.1.5)

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

NOTE 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. (8.1.6)

8.2 Sawing Method

8.2.1 The sawing method for solid flooring and the cut of the face for engineered flooring shall be as indicated in the datasheet.

Sawing Methodselect

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

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. (8.2.2)

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. (8.2.3)

8.3 Appearance Grade

8.3.1 The appearance grade shall be as indicated in the datasheet.

Appearance Gradeselect

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

8.3.2 The grade shall be certified against the grading rule governing the specified construction and species, as set out in the table below.

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

8.3.3 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.

NOTE 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. (8.3.4)

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. (8.3.5)

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. (8.3.6)

9 Dimensions, Profile, and Texture

9.1 Board Dimensions

9.1.1 The nominal thickness and face width of the flooring shall be as indicated in the datasheet.

Nominal Thicknessrange

in

0.250.31250.3750.50.6250.751

Face Widthrange

in

1.52.2533.254567891012

Engineered Face Veneer Thicknessrange

mm

0.6123456

9.1.2 The face veneer thickness requirement applies where the flooring construction indicated in the datasheet is engineered.

9.1.3 The face veneer of engineered flooring shall be measured and reported to the tolerance ANSI/HPVA EF requires.

NOTE 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. (9.1.4)

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. (9.1.5)

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. (9.1.6)

9.2 Joinery and Edge Profile

9.2.1 The joinery system shall be as indicated in the datasheet.

Joinery Systemselect

Tongue and groove, end matched

Tongue and groove, square ends

Mechanical locking profile

Square edge, blind splined

Square edge, face fastened

Butt joint, unmatched

9.2.2 The edge profile shall be as indicated in the datasheet.

Edge Profileselect

Square edge

Micro-beveled edge

Eased edge

Beveled edge

Pillowed edge

9.2.3 Flooring installed by a floating method shall have a joinery system the flooring manufacturer approves in writing for floating installation.

NOTE 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. (9.2.4)

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. (9.2.5)

9.3 Surface Texture

9.3.1 The surface texture shall be as indicated in the datasheet.

Surface Textureselect

Smooth, sanded

Wire brushed

Light hand scraped

Heavy hand scraped

Circular sawn

Skip sawn

Distressed

9.3.2 Textured flooring shall be factory textured unless the Contract Documents require site texturing, in which case the texture shall match the accepted mock-up.

NOTE 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. (9.3.3)

10 Substrate Preparation

10.1 Substrate Flatness

10.1.1 The substrate shall be prepared flat within the tolerance indicated in the datasheet, measured as the maximum deviation from a 10 ft straightedge.

Substrate Flatness Tolerance in 10 ftrange

in

0.06250.1250.18750.25

10.1.2 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.

10.1.3 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.

10.1.4 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.

10.1.5 The Contractor shall verify flatness after patching and before flooring is installed, and shall record the locations checked.

10.1.6 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.

NOTE 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. (10.1.7)

10.2 Nailable Assemblies Over Concrete

10.2.1 Where the attachment method requires a nailable substrate over a concrete slab, the assembly shall be as indicated in the datasheet.

Nailable Assembly Over Concreteselect

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

10.2.2 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.

10.2.3 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.

10.2.4 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.

10.2.5 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.

NOTE 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. (10.2.6)

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. (10.2.7)

10.3 Acoustical Underlayment

10.3.1 The acoustical underlayment shall be as indicated in the datasheet.

Acoustical Underlaymentselect

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

Minimum Impact Sound Improvement, ASTM E2179range

dB

030

10.3.2 The acoustical underlayment shall be a product the flooring manufacturer approves in writing for use beneath the specified flooring and attachment method.

10.3.3 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.

NOTE 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. (10.3.4)

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. (10.3.5)

11 Attachment

11.1 Attachment Method

11.1.1 The attachment method shall be as indicated in the datasheet.

Attachment Methodselect

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

11.1.2 Mechanically fastened attachment shall be used only over a wood substrate or a nailable assembly provided in accordance with this standard.

11.1.3 Unless the datasheet indicates a floating attachment method, solid sawn flooring shall not be installed by a floating method.

11.1.4 The attachment method shall be one the flooring manufacturer approves in writing for the specified product over the specified substrate.

NOTE 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. (11.1.5)

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. (11.1.6)

11.2 Fasteners

11.2.1 Fasteners shall conform to ASTM F1667 and shall be as indicated in the datasheet.

Fastener Typeselect

Barbed flooring cleat

Chisel point flooring staple

Screw shank flooring nail

Ring shank flooring nail

Cut flooring nail

Fastener Gaugeselect

15.5 gauge

16 gauge

18 gauge

20 gauge

Derived — the nominal thickness of the flooring, per the fastener schedule of the NWFA Installation Guidelines (by default)

Fastener Lengthrange

in

11.251.51.7522.252.5

Derived — the nominal thickness of the flooring and the substrate assembly, per the fastener schedule of the NWFA Installation Guidelines

Fastener Spacing Along Each Boardrange

in

34681012

Derived — the nominal thickness and face width of the flooring, per the fastener schedule of the NWFA Installation Guidelines

11.2.2 Fasteners shall be installed within 1 in to 3 in of each board end.

11.2.3 Not fewer than two fasteners shall be installed in every board regardless of its length.

11.2.4 Fasteners in corrosive or high-humidity environments shall be stainless steel or shall carry a coating the fastener manufacturer rates for the exposure.

11.2.5 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.

NOTE 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. (11.2.6)

11.3 Adhesives

11.3.1 The adhesive shall be as indicated in the datasheet.

Adhesive Typeselect

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

11.3.2 The trowel notch shall be as indicated in the datasheet.

Adhesive Trowel Notchselect

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

Derived — the adhesive manufacturer's published spread rate for the specified flooring construction, thickness, and face width (by default)

11.3.3 The adhesive shall be a product the flooring manufacturer approves in writing for the specified flooring over the specified substrate and moisture control measure.

11.3.4 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.

11.3.5 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.

11.3.6 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.

11.3.7 Adhesive squeezed onto the face of factory-finished flooring shall be removed immediately with the cleaner the adhesive manufacturer specifies.

NOTE 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. (11.3.8)

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. (11.3.9)

12 Expansion Provisions

12.1 A perimeter expansion space shall be provided at every wall, doorframe, column, threshold, cabinet base, and fixed object, sized as indicated in the datasheet.

Perimeter Expansion Spacerange

in

0.250.3750.50.6250.7511.251.5

Derived — the nominal thickness and face width of the flooring and the manufacturer's published expansion allowance for the installed area

12.2 The intermediate expansion provision shall be as indicated in the datasheet.

Intermediate Expansion Provisionselect

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

12.3 The perimeter expansion space shall equal or exceed the greater of the value indicated in the datasheet and the flooring manufacturer's published requirement.

12.4 The perimeter expansion space shall be left open and shall not be filled with adhesive, patching compound, sealant, or fasteners.

12.5 The perimeter expansion space shall be concealed by the base, shoe, threshold, or transition profile.

12.6 Continuous runs of flooring exceeding the flooring manufacturer's published maximum unbroken length or width shall be interrupted by an intermediate expansion provision.

12.7 Expansion provisions and their concealment shall be detailed on the flooring expansion and transition details.

NOTE 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. (12.8)

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. (12.9)

13 Floor Finish System

13.1 Finish Application

13.1.1 The finish application shall be as indicated in the datasheet.

Finish Applicationradio

○ Factory finished

○ Site finished

○ Factory finished with a site applied final coat

13.1.2 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.

NOTE 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. (13.1.3)

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. (13.1.4)

13.2 Factory-Applied Finish

13.2.1 The factory-applied finish system shall be as indicated in the datasheet.

Factory-Applied Finish Systemselect

Ultraviolet cured urethane with aluminum oxide

Ultraviolet cured urethane without aluminum oxide

Ultraviolet cured hardwax oil

Acrylic impregnated and irradiated wood

Conversion varnish

13.2.2 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.

13.2.3 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.

NOTE 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. (13.2.4)

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. (13.2.5)

13.3 Site-Applied Finish

13.3.1 The site-applied finish system shall be as indicated in the datasheet.

Site-Applied Finish Systemselect

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

Number of Site-Applied Finish Coatsrange

2345

13.3.2 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.

13.3.3 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.

13.3.4 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.

13.3.5 The floor shall not receive traffic, coverings, or furniture until the finish has reached the cure the finish manufacturer requires for that exposure.

NOTE 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. (13.3.6)

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. (13.3.7)

13.4 Color and Sheen

13.4.1 The stain color shall be as indicated in the datasheet.

Stain Colortext

Enter value...

Per drawings — the interior finish schedule (deferred by default)

13.4.2 The finish sheen shall be as indicated in the datasheet.

Finish Sheenselect

Matte

Satin

Semi-gloss

Gloss

13.4.3 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.

NOTE 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. (13.4.4)

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. (13.4.5)

14 Fire Performance

14.1 The floor covering system's critical radiant flux classification shall be as indicated in the datasheet.

Floor Covering Critical Radiant Flux Classselect

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

Derived — the occupancy classification and the location of the floor within the means of egress under the adopted building code (by default)

14.2 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.

14.3 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.

NOTE 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. (14.4)

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. (14.5)

15 Indoor Air Quality

15.1 The low-emitting materials requirement shall be as indicated in the datasheet.

Low-Emitting Materials Complianceradio

○ 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

15.2 The volatile organic compound content limit shall be as indicated in the datasheet.

Adhesive and Finish Volatile Organic Compound Content Limitradio

○ 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

15.3 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.

NOTE 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. (15.4)

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. (15.5)

16 Radiant Floor Heating

16.1 The Contractor shall confirm the extent of in-floor radiant heating indicated on the mechanical drawings before flooring is ordered.

Maximum Floor Surface Temperature Over Radiant Heatingrange

°F

758085

16.2 Flooring installed over a radiant heating system shall be a product the flooring manufacturer approves in writing for radiant service.

16.3 The radiant heating system shall be operated through the warm-up and dry-out cycle the radiant system manufacturer publishes before flooring is delivered.

16.4 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.

16.5 The adhesive used over a radiant heated slab shall be rated by its manufacturer for continuous service at the specified maximum floor surface temperature.

16.6 The radiant heating system, its controls, and its floor sensor are specified under Radiant Heating And Cooling PanelsRadiant Heating and Cooling PanelsResolves to the current edition.sync/radiant-heating-and-cooling-panels.

NOTE 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. (16.7)

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. (16.8)

17 Maple Sports Flooring

17.1 Requirements in this article apply where the flooring construction and the room use indicated in the Contract Documents call for a maple sports floor.

17.2 The sports floor system type shall be as indicated in the datasheet.

Sports Floor System Typeselect

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

17.3 The athletic performance class shall be as indicated in the datasheet.

ASTM F2772 Athletic Performance Classselect

Class 1

Class 2

Class 3

Class 4

17.4 Sports flooring shall be northern hard maple graded under the MFMA Grading Rules.

17.5 The sports floor system shall meet the specified ASTM F2772 class for force reduction, vertical deformation, ball rebound, area of deflection, and surface friction.

17.6 The flooring, resilient elements, subfloor components, vents, base, and finish shall be furnished as a coordinated system by a single manufacturer.

17.7 Game lines and logos shall be laid out as indicated on the gymnasium floor plan.

17.8 Game lines and logos shall be applied within the finish system so that they wear with the floor rather than on top of it.

17.9 The perimeter ventilating base shall be installed continuously and shall not be sealed, caulked, or blocked.

NOTE 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. (17.10)

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. (17.11)

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. (17.12)

18 Reclaimed and Salvaged Flooring

18.1 Requirements in this article apply where the Contract Documents specify reclaimed or salvaged wood flooring.

18.2 The Contractor shall submit the source of the material, the remilling and regrading basis, the kiln-drying record, and the project-specific grade definition.

18.3 Reclaimed material shall be kiln dried after remilling and shall be certified free of insects and active infestation.

18.4 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.

18.5 The Contractor shall measure and record the moisture content of reclaimed material on delivery, before acclimation begins.

18.6 Reclaimed material shall be acclimated, tested, and installed under the same moisture criteria as new flooring.

NOTE 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. (18.7)

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. (18.8)

19 Transitions and Accessories

19.1 The transition and reducer material shall be as indicated in the datasheet.

Transition and Reducer Materialselect

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

19.2 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.

19.3 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.

19.4 Transition profiles shall be fastened to the substrate rather than to the wood flooring, so that the flooring remains free to move beneath them.

19.5 Base and shoe shall be fastened to the wall rather than to the flooring.

NOTE 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. (19.6)

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. (19.7)

20 Installation

20.1 Layout and Substrate Acceptance

20.1.1 The Contractor shall inspect and accept the substrate in writing before installation begins.

20.1.2 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.

20.1.3 The Contractor shall establish a straight, square starting line referenced to the room geometry rather than to a single wall.

20.1.4 Layout shall balance the courses so that no ripped course at a wall is narrower than half the specified face width.

20.1.5 The direction of the flooring, borders, feature strips, and pattern layouts shall be as indicated on the floor finish plans.

NOTE 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. (20.1.6)

20.2 Installation of Fastened Flooring

20.2.1 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.

20.2.2 End joints in adjacent courses shall be staggered not less than 6 in, and a repeating stagger pattern shall not be used.

20.2.4 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.

20.2.5 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.

NOTE 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. (20.2.6)

20.3 Installation of Bonded Flooring

20.3.1 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.

20.3.2 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.

20.3.3 The installed floor shall be rolled or weighted within the adhesive's published open time where the adhesive manufacturer requires it.

20.3.4 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.

NOTE 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. (20.3.5)

20.4 Installation of Floating Flooring

20.4.1 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.

20.4.2 Edge joints shall be glued or engaged as the joinery system requires, with adhesive applied in the position and quantity the flooring manufacturer specifies.

20.4.3 The perimeter expansion space shall be maintained continuously around the entire field, including at pipes, columns, door frames, and transitions.

20.4.4 The floor shall not be pinned by cabinetry, fixed equipment, or fasteners set through the flooring into the substrate.

NOTE 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. (20.4.5)

20.5 Protection

20.5.1 The Contractor shall protect the completed floor from traffic, point loads, spills, and other trades until the flooring work is accepted.

20.5.2 Protective covering shall be vapor permeable and shall be a product the flooring and finish manufacturers approve.

20.5.3 Protective covering shall not be applied over a site-applied finish until the finish has reached the cure its manufacturer requires for covering.

20.5.4 Protective covering shall not be taped to the finished floor surface.

20.5.5 Rolling loads and equipment shall be moved over the floor on protective panels rather than directly on the covering.

NOTE 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. (20.5.6)

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. (20.5.7)

21 Field Quality Control

21.1 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.

21.2 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.

21.3 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.

21.4 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.

21.5 Hollow, loose, or squeaking boards shall be corrected by refastening, rebonding, or replacement.

21.6 Where the condition is present in more than 2% of the floor area, the Contractor shall investigate and report the cause before making repairs.

21.7 Sports flooring shall be verified against the specified ASTM F2772 class before acceptance, by field test where the Contract Documents require one.

21.8 The Contractor shall bear the cost of retesting and reinspection following a failed test or a rejected area.

21.9 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.

NOTE 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. (21.10)

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. (21.11)

22 Cleaning and Owner Maintenance

22.1 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.

22.2 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.

22.3 The Contractor shall demonstrate the routine cleaning procedure to the Owner's maintenance personnel before turnover.

22.4 Walk-off matting at exterior entrances is specified under Entrance FlooringEntrance Flooring and Walk-Off SystemsResolves to the current edition.sync/entrance-flooring.

NOTE 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. (22.5)

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. (22.6)

23 Delivery, Storage, and Handling

23.1 Flooring, adhesives, underlayment, and accessories shall be delivered in the manufacturer's original packaging with grade, species, lot, and production run identification intact.

23.2 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.

23.3 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.

23.4 Flooring shall be broken out, opened, or cross-stacked for acclimation as the flooring manufacturer directs.

23.5 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.

23.6 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.

23.7 Adhesives and finishes past their published shelf life shall not be used.

23.8 The Contractor shall bear the cost of material damaged by storage in conditions outside those specified.

NOTE 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. (23.9)

24 Warranty

24.1 The manufacturer product warranty period shall be as indicated in the datasheet.

Manufacturer Product Warranty Periodrange

years

15101520253050

24.2 The factory finish wear-through warranty period shall be as indicated in the datasheet.

Factory Finish Wear-Through Warranty Periodrange

years

1351015202530

24.3 The installation workmanship warranty period shall be as indicated in the datasheet.

Installation Workmanship Warranty Periodrange

years

1235

24.4 The flooring manufacturer shall warrant the material against manufacturing, milling, and grading defects for the specified period from the date of Substantial Completion.

24.5 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.

24.6 Warranties shall be issued in the Owner's name and shall be transferable to a subsequent owner of the building.

24.7 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.

24.8 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.

24.9 The Contractor shall retain the moisture and acclimation record for the duration of the warranty period and shall furnish it on request.

NOTE 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. (24.10)

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. (24.11)

25 Spare and Extra Materials

25.1 The attic stock quantity shall be as indicated in the datasheet.

Attic Stock Quantityrange

% of installed area

123510

25.2 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.

25.3 The Contractor shall deliver touch-up material and, for site-finished floors, matching stain and finish material sufficient for localized repair.

25.4 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.

NOTE 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. (25.5)