+---
+title: Entrance Flooring and Walk-Off Systems
+category: Architectural / Finishes
+toc_depth: 3
+description: >
+ When to use: Permanently installed entrance flooring and walk-off systems specified to capture moisture, soil, grit, and snowmelt at building entries before they are tracked into occupied space — recessed and surface-mounted aluminum and extruded grid grilles and gratings, roll-up grates, recessed mats, and walk-off carpet and fiber tile in the interior wiper zone. Covers the three-zone (scraper / scraper-wiper / wiper) matting design principle and walk-off length, grille type and rail construction, frame and recess-depth coordination, tread-surface inserts (vinyl, rubber, carpet, abrasive, serrated aluminum tread), load rating (pedestrian, rolling cart and wheelchair, occasional vehicular), accessibility (grating opening size and orientation, change-in-level and bevel limits, firm and stable surface), slip resistance, flammability and smoke performance, drainage, installation, and cleaning and maintenance.
+ Not intended for: Field-installed broadloom and modular carpet outside the entrance wiper zone (see [[sync/carpet]]); resilient flooring such as vinyl and rubber sheet and tile in the field (see [[sync/resilient-flooring]]); ceramic and porcelain tile floors (see [[sync/ceramic-tile]]); natural-stone tile floors (see [[sync/natural-stone-tile]]); loose, unsecured rugs and temporary mats not part of a permanent walk-off system; exterior pedestrian paving, trench drains, and area drains; structural floor trench, pit, and recess forming in the slab (coordinate the recess with the cast-in-place concrete and the structural drawings); roof and balcony pedestal pavers.
+---
+
+# Scope
+
+This standard governs the materials, configuration, and installation of permanently installed entrance flooring and walk-off systems — recessed and surface-mounted aluminum and extruded grid grilles and gratings, roll-up grates, recessed mats, and walk-off carpet and fiber tile — provided at building entrances to capture moisture, soil, grit, sand, and snowmelt from foot traffic before it is carried onto the interior finish floor. An entrance flooring system is not a doormat; it is the first line of defense for every downstream finish in the building. Soil and water that are not captured at the door are ground into corridor and lobby flooring, abrade and dull it, raise cleaning frequency and cost, and create a slip hazard on hard surfaces wherever a wet shoe transitions from the entry onto polished stone, tile, or resilient flooring. The single largest determinant of how much soil and moisture a building tracks in is the length and quality of the walk-off provided at the entrance, and that is a design decision made in this standard, not an afterthought left to a loose rug.
+
+A walk-off system is a sequence, not a single product. The recognized design principle is a three-zone progression: an exterior scraper zone that removes mud, grit, sand, and snow from the shoe before the door; a transitional scraper-wiper zone at the threshold or in the vestibule that scrapes remaining debris and begins wicking moisture; and an interior wiper zone that dries the shoe and traps the last fine soil and moisture below its surface. The zones work in series — an interior wiper carpet installed without a hard scraper ahead of it is quickly overwhelmed with grit and mud and becomes saturated, while a scraper grille with no wiper behind it leaves the shoe wet and tracks water onto the lobby floor. The Contractor and the Architect shall treat the entrance as a system spanning all three zones and shall provide adequate total walk-off length, not merely a single mat at the door.
+
+The entrance flooring system is also a structural and accessibility coordination problem. A recessed grille requires a slab recess of the correct depth formed in the cast-in-place concrete, with drainage where exposed to weather, and the recess depth, the frame, and the grille thickness shall be reconciled so the finished tread surface is flush with the adjacent finish floor within the accessible change-in-level limit. Coordinate the slab recess and its drainage with the structural and concrete drawings before the slab is placed; a recess formed to the wrong depth after the fact is expensive and disruptive to correct. Coordinate the interior wiper zone, where it is walk-off carpet or fiber tile, with [[sync/carpet]]; coordinate transitions to adjacent hard finishes with [[sync/ceramic-tile]], [[sync/natural-stone-tile]], and [[sync/resilient-flooring]] so that finish-floor elevations and thresholds reconcile and accessible-route level changes stay within limits.
+
+# Referenced Standards
+
+All materials, testing, and installation shall comply with the latest edition adopted by the Authority Having Jurisdiction for each of the following standards. Where the contract documents, a referenced standard, or the 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 manufacturer's written installation instructions define the conditions under which the product warranty is valid, and the Contractor shall follow them in addition to this standard.
+
+| Standard | Title |
+|----------|-------|
+| ICC A117.1 | Accessible and Usable Buildings and Facilities |
+| 2010 ADA Standards for Accessible Design | U.S. Department of Justice / U.S. Access Board accessibility requirements |
+| IBC | International Building Code (current edition adopted by jurisdiction) |
+| ANSI A326.3 | Test Method for Measuring Dynamic Coefficient of Friction of Hard Surface Flooring Materials |
+| ASTM E648 | Standard Test Method for Critical Radiant Flux of Floor-Covering Systems Using a Radiant Heat Energy Source |
+| NFPA 253 | Standard Method of Test for Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat Energy Source |
+| ASTM E662 | Standard Test Method for Specific Optical Density of Smoke Generated by Solid Materials |
+| NFPA 258 | Standard Research Test Method for Determining Smoke Generation of Solid Materials |
+| ASTM D2859 | Standard Test Method for Ignition Characteristics of Finished Textile Floor Covering Materials (Pill Test) |
+| 16 CFR 1630 (DOC FF 1-70) | Standard for the Surface Flammability of Carpets and Rugs |
+| CRI | Carpet and Rug Institute entrance-flooring and walk-off guidance |
+| CRI Green Label Plus | Carpet and Rug Institute Indoor Air Quality Testing Program |
+| ASTM B221 | Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes |
+| ASTM B209 | Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate |
+| LEED (USGBC) | Indoor environmental quality entryway-systems requirement (10-foot permanent entryway system) |
+
+The accessibility provisions of ICC A117.1 and the 2010 ADA Standards are mandatory at any entrance on an accessible route and govern grating opening size and orientation, change in level at the perimeter and at transitions, and the requirement for a firm, stable, and slip-resistant surface. Walk-off carpet and fiber-tile inserts are textile floor coverings and shall pass the federal surface-flammability pill test of 16 CFR 1630 (DOC FF 1-70), technically equivalent to ASTM D2859, as a baseline; where the entrance is in or opens onto a corridor or exit regulated by the IBC, the wiper-zone textile is additionally regulated for critical radiant flux per ASTM E648 (technically equivalent to NFPA 253). ANSI A326.3 is the test method for the dynamic coefficient of friction of the hard tread surfaces. The CRI provides the consensus guidance on walk-off length and zone function, and a permanently installed entryway system of not less than 10 feet in the primary direction of travel at each regularly used exterior entrance is the threshold recognized by LEED for the entryway-systems requirement.
+
+# Submittals
+
+## Action Submittals
+
+The Contractor shall submit the following for the Architect's review prior to fabrication and installation. Because the recessed-grille system depends on a slab recess formed by others, the shop drawings and the recess-depth coordination shall be reviewed before the slab is placed wherever the system is recessed.
+
+- Product data for each entrance flooring system, identifying the type (recessed grille, surface-mounted grille, roll-up grate, recessed mat, or walk-off carpet/fiber tile), the rail or grid material and finish, the tread-insert type and color, the load rating, the overall thickness, and the manufacturer's written installation instructions
+- Shop drawings showing each mat or grille in plan with overall dimensions and field-cut layout, the frame profile and corner construction, the recess depth and drainage where recessed, the relationship of the finished tread surface to the adjacent finish floor, and the direction of the rails relative to the primary direction of travel
+- Samples of each tread-insert type and color, of each rail and frame finish, and of the walk-off carpet or fiber tile where used
+- Accessibility documentation: the grating opening dimension and orientation, the change in level at the frame perimeter and at any transition, and confirmation that the tread surface is firm, stable, and slip-resistant
+- Slip-resistance documentation: the dynamic coefficient of friction of the hard tread surfaces tested per ANSI A326.3, for the use classification (interior wet) applicable to an entrance
+- Flammability documentation for walk-off carpet and fiber-tile inserts: the 16 CFR 1630 / ASTM D2859 pass result, and the ASTM E648 critical radiant flux value and class where corridor or exit installation applies
+- Maintenance instructions describing the cleaning method and frequency, the procedure for lifting roll-up or hinged grilles and individual tiles to clean the recess and drain beneath, and replacement of worn tread inserts
+
+```datasheet
+label: Action Submittals Required
+type: checkbox
+options:
+ - "Product data — each entrance flooring system"
+ - "Shop drawings — plan, frame, recess depth, drainage, rail direction"
+ - "Samples — tread inserts, rail/frame finish, walk-off carpet/tile"
+ - "Accessibility documentation (grating opening, change in level, firm/stable/slip-resistant)"
+ - "Slip-resistance documentation (ANSI A326.3 DCOF, interior wet)"
+ - "Flammability documentation for textile inserts (16 CFR 1630 / ASTM E648)"
+ - "Maintenance instructions"
+default: "Shop drawings — plan, frame, recess depth, drainage, rail direction"
+```
+
+## Closeout Submittals
+
+- Manufacturer warranty documentation for each entrance flooring system, executed in the Owner's name
+- Record shop drawings of the as-installed systems, including the recess depths and frame elevations actually achieved
+- Attic-stock transmittal documenting spare tread inserts and any spare tiles or grille sections delivered to the Owner
+
+# Quality Assurance
+
+## Installer Qualifications
+
+Entrance flooring shall be installed by an installer experienced in the specific system type and, for recessed systems, in setting frames flush to a finished floor over a formed recess. The flush relationship between the tread surface and the adjacent finish floor is the most common failure of installation craft: a frame set too high creates a trip hazard and a change in level exceeding the accessible limit, and a frame set too low ponds water and collects debris at the perimeter. The Contractor shall not begin installation of a recessed system until the recess has been verified for depth, level, and drainage.
+
+```datasheet
+label: Installer Qualification
+type: radio
+options:
+ - "Experienced entrance-flooring installer per manufacturer instructions"
+ - "Manufacturer-certified installer (where required to validate warranty)"
+default: "Experienced entrance-flooring installer per manufacturer instructions"
+```
+
+## Mock-Up
+
+```datasheet
+label: Mock-Up Required
+type: radio
+options:
+ - "Yes — install one complete entrance, including frame, transition, and tread inserts"
+ - "No"
+default: "No"
+```
+
+Where a mock-up is required, the Contractor shall install one complete entrance system at a location directed by the Architect, including the frame, the transition to the adjacent finish floor, and the specified tread inserts, to establish the acceptable standard for flushness, transition detailing, rail direction, and insert appearance. The mock-up shall remain available for comparison throughout the work.
+
+## Coordination of the Recess
+
+Before the slab is placed, the Contractor shall coordinate the location, plan dimensions, depth, and drainage of every floor recess that will receive a recessed grille or mat with the structural and concrete drawings and with the frame manufacturer's required recess depth. The recess depth shall match the frame and grille thickness so the finished tread is flush with the adjacent finish floor; the recess shall be square, level, and dimensioned to receive the frame with the manufacturer's required clearance; and where the entrance is exposed to weather or to wash-down, the recess shall be sloped to a drain or weep so captured water does not pond beneath the grille. A recess formed to the wrong depth or without drainage is the single most expensive and disruptive error in this work, because it is fixed in concrete before the grille is ever ordered.
+
+# Service Conditions
+
+## Exposure and Climate
+
+```datasheet
+label: Entrance Exposure
+type: radio
+drawing_ref: true
+options:
+ - "Interior vestibule / lobby (conditioned, protected from direct weather)"
+ - "Exterior-exposed entry (direct rain, snow, freeze-thaw)"
+ - "Covered exterior (canopy / overhang, wind-driven moisture)"
+default: "Interior vestibule / lobby (conditioned, protected from direct weather)"
+```
+
+The exposure determines the materials, the drainage, and the walk-off length. An interior vestibule or lobby grille is protected from direct weather and is selected primarily for soil and moisture capture and appearance. An exterior-exposed or covered exterior entry sees rain, wind-driven moisture, and in cold climates snow, ice, and freeze-thaw, and shall be provided with drainage beneath the grille, corrosion-resistant aluminum and stainless or coated hardware, tread inserts that perform when wet and frozen, and additional walk-off length to handle the heavier moisture and grit load. Snow and ice that melt beneath a grille and refreeze will heave inserts and jam roll-up grilles if the recess does not drain.
+
+## Traffic Volume and Walk-Off Length
+
+```datasheet
+label: Total Walk-Off Length (Primary Direction of Travel)
+type: range
+unit: ft
+drawing_ref: true
+options:
+ min: 6
+ max: 30
+ setpoints: [6, 10, 12, 15, 20, 25, 30]
+default: 15
+```
+
+The total walk-off length across all zones is the governing performance parameter of the entrance and shall be provided in the primary direction of travel. Research-based guidance recommends on the order of 15 to 25 feet of total walk-off for effective soil and moisture capture; the CRI guidance is commonly cited as 12 to 15 feet for office buildings and 20 to 25 feet for high-traffic and high-cleanliness occupancies such as grocery stores, healthcare facilities, and schools. A minimum of 10 feet of permanently installed entryway system in the primary direction of travel at each regularly used exterior entrance is the threshold recognized by LEED for the entryway-systems requirement and should be treated as a floor, not a target. Insufficient walk-off length is the most common functional failure of entrance flooring: a 3-foot mat at the door captures only a fraction of the soil and moisture and saturates within hours of a storm, after which it tracks moisture rather than removing it. The walk-off length, the zone arrangement, and the mat extents shall be shown on the [[drawing: finish plan]].
+
+# System Types and Configurations
+
+## Walk-Off Zone Arrangement
+
+```datasheet
+label: Walk-Off Zone Arrangement
+type: select
+drawing_ref: true
+options:
+ - "Three-zone — exterior scraper + transitional scraper-wiper + interior wiper"
+ - "Two-zone — scraper grille + interior wiper carpet/tile"
+ - "Single-zone — recessed grille at entrance only"
+ - "Single-zone — interior wiper carpet/tile only (protected interior entrance)"
+default: "Two-zone — scraper grille + interior wiper carpet/tile"
+```
+
+The walk-off shall be arranged as a sequence of zones appropriate to the exposure and traffic. The full three-zone arrangement — an exterior scraper to remove mud, grit, and snow before the door, a transitional scraper-wiper zone at the threshold or vestibule, and an interior wiper to dry the shoe and trap fine soil — is appropriate for high-traffic and weather-exposed entrances. A two-zone arrangement of a recessed scraper grille followed by an interior wiper carpet covers the majority of commercial entrances. A single recessed grille or a single interior wiper may be adequate for a protected, low-traffic interior entrance. The zones shall be continuous and in series across the primary direction of travel, with no untreated gap between them where a shoe re-soils before reaching the interior floor.
+
+## System Type
+
+```datasheet
+label: Entrance Flooring System Type
+type: select
+drawing_ref: true
+options:
+ - "Recessed aluminum/extruded grid grille (rails with tread inserts)"
+ - "Surface-mounted grid grille with ramped/beveled edge frame"
+ - "Roll-up grille / roll-up grate (linked rails, rolls for cleaning)"
+ - "Recessed mat (resilient/rubber link or solid mat in recess)"
+ - "Walk-off carpet / fiber tile (interior wiper zone)"
+default: "Recessed aluminum/extruded grid grille (rails with tread inserts)"
+```
+
+The system type shall be selected for the zone, the exposure, the load, and the cleaning method. A recessed aluminum or extruded grid grille — parallel tread rails carrying replaceable insert strips, set into a slab recess flush with the finish floor — is the standard scraper and scraper-wiper system for primary entrances, because the open spaces between rails let soil and water fall below the walking surface and out of the traffic path. A surface-mounted grid grille sits on top of the finished floor within a ramped or beveled-edge frame and is used where no recess can be formed, such as in renovation; the ramped frame is required so the raised mat does not create a non-compliant change in level. A roll-up grille has its rails linked by flexible connectors so the entire grille can be rolled up to clean the recess and any drain beneath it, which is the practical advantage where the recess collects significant grit and water. A recessed mat is a resilient or rubber-link product set in a shallow recess where a rail grille is not desired. Walk-off carpet and fiber tile serve the interior wiper zone, where the function is to dry the shoe and absorb the last moisture rather than to scrape.
+
+### Grille Rail Construction
+
+```datasheet
+label: Grille Rail / Grid Construction
+type: select
+options:
+ - "Extruded aluminum tread rails, individual (lift-out) grille"
+ - "Extruded aluminum tread rails, hinged grille (rigid, hinged sections)"
+ - "Extruded aluminum tread rails, roll-up grille (flexible cable/connector linked)"
+ - "Not applicable — recessed mat or walk-off carpet/tile"
+default: "Extruded aluminum tread rails, roll-up grille (flexible cable/connector linked)"
+```
+
+The rails of a grid grille shall be extruded aluminum (ASTM B221) of an alloy and temper rated for foot-traffic floor service and for the load classification specified. Rails are assembled into a grille in one of three ways. An individual lift-out grille is built of rigid sections that lift out for cleaning; a hinged grille has rigid sections joined by hinges so it folds for cleaning while remaining rigid in plane; and a roll-up grille has the rails linked by flexible cables or connectors so the whole grille rolls up, which best suits recesses that must be cleaned out frequently and any recess with a drain beneath it. The connector and hinge hardware shall be corrosion-resistant where the entrance is exposed to weather or wash-down.
+
+### Tread Insert
+
+```datasheet
+label: Tread-Surface Insert
+type: select
+drawing_ref: true
+options:
+ - "Vinyl (corrugated/ribbed) — interior, quiet, easy clean"
+ - "Rubber tread — exterior/wet, slip resistant, durable"
+ - "Carpet / fiber insert — wiper, moisture absorption"
+ - "Abrasive (carborundum/carbide grit) strip — maximum scraping/slip resistance"
+ - "Serrated/grooved aluminum tread — heavy-duty scraping, no insert"
+default: "Carpet / fiber insert — wiper, moisture absorption"
+```
+
+The tread insert is the walking surface carried by the rails and is selected for the zone function and the exposure. A corrugated or ribbed vinyl insert is quiet, comfortable, and easy to clean and suits interior scraper-wiper service. A rubber tread is durable and slip-resistant when wet and suits exterior and wet exposures. A carpet or fiber insert is the wiper surface that absorbs and holds moisture and traps fine soil and is appropriate for the interior wiper zone. An abrasive carborundum or carbide-grit strip provides the most aggressive scraping and the highest slip resistance and is used in exterior scraper rails and where falls are a heightened concern. A serrated or grooved bare-aluminum tread provides heavy-duty scraping with no insert to wear out. Inserts may be combined across the rails of a single grille — for example, abrasive at the leading rails grading to carpet at the trailing rails — to scrape first and wipe last within one mat. Inserts shall be field-replaceable so a worn insert can be renewed without replacing the grille.
+
+### Frame and Recess Depth
+
+```datasheet
+label: Frame Type and Recess Depth
+type: select
+drawing_ref: true
+options:
+ - "Recessed frame — shallow recess (approx. 3/8 in to 1/2 in finished depth)"
+ - "Recessed frame — standard recess (approx. 5/8 in to 13/16 in finished depth)"
+ - "Recessed frame — deep pit (approx. 1-3/4 in to 4 in, with drainage)"
+ - "Surface-mounted frame — ramped/beveled edge, no recess"
+default: "Recessed frame — standard recess (approx. 5/8 in to 13/16 in finished depth)"
+```
+
+The frame shall match the grille or mat thickness and the recess depth so the finished tread surface is flush with the adjacent finish floor within the accessible change-in-level limit. Recessed systems are commonly available in a shallow profile on the order of 3/8 to 1/2 inch, a standard profile on the order of 5/8 to 13/16 inch, and deep-pit profiles from roughly 1-3/4 inches to 4 inches for heavy-duty and weather-exposed entrances that require drainage beneath the grille. A surface-mounted frame is used only where no recess can be formed and shall have a ramped or beveled edge on all exposed sides so the raised mat does not create a non-compliant change in level or a trip hazard. The recess depth, the frame, and the grille thickness shall be reconciled on the shop drawings and verified in the field before the grille is set.
+
+### Drainage
+
+```datasheet
+label: Drainage Beneath Recessed System
+type: radio
+drawing_ref: true
+options:
+ - "None — interior, protected entrance (no standing water expected)"
+ - "Sloped recess to weep / floor drain"
+ - "Recess with dedicated drain connection (heavy moisture / wash-down)"
+default: "None — interior, protected entrance (no standing water expected)"
+```
+
+Where the entrance is exposed to weather, to snowmelt, or to wash-down cleaning, the recess shall drain so captured water does not pond beneath the grille, stagnate, freeze, or wick back up into the tread. A sloped recess directing water to a weep or a floor drain is adequate for most covered and lightly exposed entrances; a recess with a dedicated drain connection is appropriate for heavy moisture and for wash-down maintenance. An interior, protected entrance with no standing water expected need not be drained. A roll-up grille is preferred over a fixed grille wherever a drain is provided, because the grille must be lifted to clean the recess and the drain.
+
+### Load Rating
+
+```datasheet
+label: Load Rating (Rolling Load per Wheel)
+type: select
+drawing_ref: true
+options:
+ - "Pedestrian and light rolling (carts, strollers, wheelchairs) — approx. 300 lb/wheel"
+ - "Heavy rolling traffic (loaded carts, gurneys, pallet jacks) — approx. 350 to 500 lb/wheel"
+ - "Maximum / institutional duty — approx. 1,000 lb/wheel"
+ - "Occasional vehicular (loading entrance, valet) — manufacturer-rated for the wheel load"
+default: "Pedestrian and light rolling (carts, strollers, wheelchairs) — approx. 300 lb/wheel"
+```
+
+The grille shall be rated for the heaviest rolling load that will cross it, expressed as load per wheel, not merely for foot traffic. Standard grid grilles are commonly rated on the order of 300 pounds per wheel, which covers pedestrian traffic, hand carts, strollers, and wheelchairs; heavy-duty grilles are rated on the order of 350 to 500 pounds per wheel for loaded carts, hospital gurneys, and pallet jacks; and institutional-duty grilles reach approximately 1,000 pounds per wheel. Where the entrance receives occasional vehicular traffic — a loading entrance or a valet drive-over — the grille shall be specifically manufacturer-rated for that wheel load and rail spacing, because a pedestrian-rated grille will deflect and fail under a vehicle wheel. A grille that is under-rated for its rolling load will deflect, loosen its inserts, and ravel its rails at the leading edge.
+
+### Mat Size and Layout
+
+```datasheet
+label: Mat Size and Layout
+type: text
+drawing_ref: true
+default: "As shown on the finish plan — full entrance width, total walk-off length per the specified zone arrangement"
+```
+
+Each mat and grille shall be sized to the full clear width of the entrance opening — wall to wall and jamb to jamb — and to the total walk-off length of its zone, as shown on the [[drawing: finish plan]]. A mat narrower than the door allows traffic to bypass it on one side and re-soil downstream; a mat shorter than the specified zone length under-performs. Large grilles shall be detailed in field-installable sections with the section joints coordinated so they fall out of the most concentrated traffic path where practical. The rails shall run perpendicular to the primary direction of travel so that every step crosses the open spaces between rails.
+
+# Accessibility
+
+## Grating Openings
+
+```datasheet
+label: Grating Opening Size and Orientation (ICC A117.1 / ADA)
+type: radio
+options:
+ - "Openings shall not pass a 1/2 in sphere; elongated openings oriented with long dimension perpendicular to travel"
+ - "Openings limited to 1/2 in in both dimensions (no dominant travel direction)"
+default: "Openings shall not pass a 1/2 in sphere; elongated openings oriented with long dimension perpendicular to travel"
+```
+
+On an accessible route, openings in the entrance flooring surface — the spaces between grille rails — shall not permit the passage of a ½-inch-diameter sphere, so that a cane tip, a high heel, or a small wheel cannot drop into or catch in the opening. Where the openings are elongated, as the spaces between parallel rails are, the long dimension of the opening shall be oriented perpendicular to the dominant direction of travel, which conveniently aligns with the requirement that the rails run perpendicular to travel for effective scraping. Where there is no dominant direction of travel, openings shall be limited to ½ inch in both dimensions. A grille with the rails running parallel to travel, or with gaps wider than ½ inch, is both a less effective scraper and an accessibility and trip hazard.
+
+## Change in Level and Transitions
+
+```datasheet
+label: Change in Level at Frame / Transition (ICC A117.1 / ADA)
+type: radio
+options:
+ - "Flush — change in level not more than 1/4 in (no treatment required)"
+ - "1/4 in to 1/2 in — beveled, slope not steeper than 1:2"
+ - "Surface-mounted — ramped/beveled frame edge on all exposed sides"
+default: "Flush — change in level not more than 1/4 in (no treatment required)"
+```
+
+The change in level between the entrance flooring tread surface and the adjacent finish floor shall be controlled at every edge of the system on an accessible route. A change in level of not more than ¼ inch is permitted without treatment; a change in level between ¼ inch and ½ inch shall be beveled with a slope not steeper than 1:2; and a change in level greater than ½ inch is not permitted at an entrance mat and shall be eliminated by correcting the recess depth or by ramping. A surface-mounted grille, which necessarily sits above the floor, shall have a ramped or beveled frame edge on all exposed sides to bring the change in level within these limits.
+
+## Firm, Stable, and Slip-Resistant Surface
+
+The entrance flooring surface on an accessible route shall be firm, stable, and slip-resistant. The grille shall be set so it does not rock, shift, or deflect underfoot; inserts shall be secured so they do not lift or curl; and roll-up and link mats shall lie flat and not ripple. The tread surface shall provide slip resistance appropriate to a surface that is wet in normal use, which is the defining condition of an entrance.
+
+```datasheet
+label: Tread Slip Resistance (ANSI A326.3, Interior Wet)
+type: range
+unit: DCOF
+options:
+ min: 0.42
+ max: 0.60
+ step: 0.01
+setpoints: [0.42, 0.50, 0.55]
+default: 0.42
+```
+
+The dynamic coefficient of friction of the hard tread surfaces — vinyl, rubber, and aluminum treads — shall be measured per ANSI A326.3 for the interior-wet use classification and shall be not less than 0.42, the recognized minimum for level interior floors expected to be wet in use. Higher values are appropriate for the exterior scraper zone and for entrances where wind-driven rain, snowmelt, or wash-down keep the surface persistently wet; abrasive carborundum inserts provide the highest slip resistance for these conditions. The DCOF value is a comparative measure and does not by itself guarantee that a person will not slip; adequate walk-off length to actually dry the shoe is the primary slip-safety measure, because the most slippery point at any entrance is the dry hard floor immediately beyond a wet shoe that the walk-off failed to dry.
+
+# Flammability — Textile Inserts and Walk-Off Carpet
+
+```datasheet
+label: Critical Radiant Flux Class — Textile Wiper (ASTM E648 / NFPA 253)
+type: radio
+drawing_ref: true
+options:
+ - "Class I — critical radiant flux not less than 0.45 W/cm² (exits, corridors in institutional occupancies)"
+ - "Class II — critical radiant flux not less than 0.22 W/cm² (corridors in other occupancies)"
+ - "Pill test only (16 CFR 1630 / ASTM D2859) — entrance not regulated for radiant flux"
+default: "Pill test only (16 CFR 1630 / ASTM D2859) — entrance not regulated for radiant flux"
+```
+
+Walk-off carpet and fiber-tile inserts are textile floor coverings and shall pass the federal surface-flammability pill test of 16 CFR 1630 (DOC FF 1-70), technically equivalent to ASTM D2859, as a baseline. Where the entrance is within or opens onto an interior corridor or exit regulated by the IBC, the textile wiper is additionally regulated for critical radiant flux measured per ASTM E648 (technically equivalent to NFPA 253), and the applicable Class I (not less than 0.45 W/cm²) or Class II (not less than 0.22 W/cm²) shall be confirmed from the building code compliance path for the location. Most entrance vestibules are not corridors and are regulated by the pill test alone, but the Architect shall confirm the classification rather than assume it. Aluminum, vinyl, and rubber tread components are not textiles and are not subject to the textile flammability tests.
+
+```datasheet
+label: Smoke Density Limit — Textile Wiper (ASTM E662 / NFPA 258)
+type: radio
+options:
+ - "Required — specific optical density of smoke shall not exceed 450 (flaming mode)"
+ - "Not separately regulated at this location"
+default: "Not separately regulated at this location"
+```
+
+Where the building code or the Owner's program requires limiting smoke generation for the textile wiper, the specific optical density of smoke shall be measured per ASTM E662 (NFPA 258) and shall not exceed the limit stated.
+
+```datasheet
+label: Indoor Air Quality Certification — Walk-Off Carpet / Fiber Tile
+type: radio
+options:
+ - "CRI Green Label Plus"
+ - "FloorScore / CDPH Section 01350 (equivalent low-emitting certification)"
+ - "Not required"
+default: "Not required"
+```
+
+Where indoor air quality is a project requirement and the wiper zone is walk-off carpet or fiber tile, the textile and its adhesive shall be certified to a recognized low-emitting-materials program such as CRI Green Label Plus or an equivalent FloorScore / CDPH Section 01350 certification.
+
+# Installation
+
+## Recess and Frame Setting
+
+The Contractor shall verify the recess for depth, level, squareness, and drainage before setting the frame. The recess shall be clean, sound, and free of debris and standing water; where a drain is provided beneath the grille, it shall be confirmed clear and the recess slope confirmed to drain to it. The frame shall be set level and square and anchored so the top of the frame establishes a finished tread surface flush with the adjacent finish floor within the accessible change-in-level limit. Frames set in a green slab or in a grout bed shall be shimmed and braced so they do not shift before the bed has set. The transition from the frame to each adjacent finish — stone, tile, resilient, or carpet — shall be detailed so the finish-floor elevations reconcile and the level change at the perimeter stays within limits.
+
+## Grille and Insert Placement
+
+The grille shall be installed with the rails running perpendicular to the primary direction of travel and shall be field-cut and fitted so it lies flat, fully supported by the frame, with the manufacturer's clearance at the frame perimeter and no rocking or deflection underfoot. Tread inserts shall be installed in the correct rails per the approved layout, fully seated and secured so they do not lift, curl, or migrate, with the abrasive, scraper, and wiper inserts located as shown where inserts are mixed within a grille. Roll-up and link grilles shall lie flat without ripples or raised connectors.
+
+## Walk-Off Carpet and Fiber-Tile Installation
+
+Where the interior wiper zone is walk-off carpet or fiber tile, it shall be installed in accordance with the carpet provisions of [[sync/carpet]] — including subfloor preparation, moisture acceptance, and securement appropriate to the format — and shall be coordinated so its finished surface meets the grille frame and the adjacent finish floor within the accessible change-in-level limit, with a beveled transition where required. The wiper zone shall be securely attached so it does not shift or ripple under traffic and rolling loads.
+
+# Cleaning and Maintenance
+
+Entrance flooring is the hardest-working flooring in the building and only performs if it is maintained; a grille whose recess is full of compacted grit, or a wiper carpet that is saturated and never extracted, has stopped capturing soil and is now redistributing it. The Contractor shall deliver maintenance instructions describing the routine cleaning method and frequency for each system, the procedure to lift the grille — individual sections, hinged sections, or the rolled-up grille — to vacuum and wash the recess and clear any drain beneath it, and the method to extract or replace saturated wiper inserts. Roll-up and hinged grilles are specified in part because they make this recess cleaning practical; a fixed grille over an un-drained recess that cannot be lifted will silt up and fail. Worn, torn, or permanently soiled tread inserts shall be replaced from attic stock rather than left in service, because a worn insert no longer scrapes or wipes and a torn insert is a trip hazard.
+
+```datasheet
+label: Spare Tread Inserts / Tiles (Attic Stock)
+type: range
+unit: % of installed insert length/area
+options:
+ min: 2
+ max: 5
+ step: 1
+default: 3
+```
+
+The Contractor shall deliver to the Owner spare tread inserts of each type and color, and spare grille sections or wiper tiles where used, in the percentage of installed insert length or area stated, so the Owner can renew worn or damaged inserts with matching material. Spare material shall be labeled by product type and color.
+
+# Warranty
+
+```datasheet
+label: Manufacturer Warranty Period
+type: select
+unit: years
+options:
+ - "1 year (standard limited)"
+ - "2 years"
+ - "5 years (heavy-duty grille systems)"
+ - "Lifetime limited (rail/frame structure, premium systems)"
+default: "5 years (heavy-duty grille systems)"
+```
+
+The manufacturer shall warrant the entrance flooring system against defects in materials and workmanship for the period stated; premium grid-grille systems commonly carry a long-term or lifetime limited warranty on the rail and frame structure, with tread inserts treated as wearing items on a shorter term. The Contractor shall warrant the installation — including recess and drainage coordination, frame setting and flushness, grille fit, insert securement, and transitions to adjacent finishes — against defective workmanship for the project warranty period. Failures arising from a recess formed to the wrong depth or without required drainage, from loads exceeding the grille's rated rolling load, or from maintenance contrary to the manufacturer's instructions are excluded.
+
+```datasheet
+label: Installation Workmanship Warranty Period
+type: select
+options:
+ - "1 year from substantial completion"
+ - "2 years from substantial completion"
+default: "1 year from substantial completion"
+```