Why Commercial Flooring Fire Ratings Are Often Misread

A single fire-rating number on a flooring cut sheet often gets asked to answer three different questions it was never designed to answer. Specifiers routinely treat a floor covering’s flame-propagation classification as proof of interior-finish compliance, and both as proof that the underlying slab or floor-ceiling assembly carries structural fire resistance. It doesn’t work that way.

There are three distinct fire-performance disciplines at play on any commercial floor: how the floor covering itself resists radiant heat and flame travel across its surface (ASTM E648, referenced by NFPA 253), how an interior finish material performs in a vertical flame-spread and smoke test (ASTM E84/UL 723, or CAN/ULC-S102.2 in Canada), and whether the load-bearing floor assembly can hold back fire and heat transfer for a rated time period (ASTM E119/UL 263). A product can pass one of these tests and say nothing about the other two. Armstrong Flooring Commercial’s published Standards FAQs make this point directly to specifiers: a Class I critical radiant flux rating under ASTM E648 describes the floor-covering system, not the fire-resistance rating of the concrete slab or the assembly beneath it.

This matters most at the point where a general contractor, architect, or facility owner assumes “fire-rated flooring” satisfies a code official’s request for a “fire-rated floor assembly.” Those are different submittals, reviewed under different code sections, and an AHJ who catches the substitution will send the package back.

U.S. Test Methods and Ratings at a Glance

U.S. commercial flooring fire performance is governed by three separate test regimes: ASTM E648/NFPA 253 for floor-covering critical radiant flux, ASTM E84/UL 723 for interior-finish flame spread and smoke, and ASTM E119/UL 263 for structural fire resistance of the complete floor assembly. Each has its own classification system and its own place in a specification.

ASTM E648 and NFPA 253: Critical Radiant Flux Explained

ASTM E648, referenced by NFPA 253, tests a horizontally mounted floor-covering system under a radiant heat panel and converts the flame’s burn distance before self-extinguishing into a critical radiant flux value. Class I requires at least 0.45 W/cm²; Class II requires at least 0.22 W/cm². Corridors and exitways in many occupancies require Class I.

NFPA’s current edition, NFPA 253 (2023), describes the test as evaluating critical radiant flux of floor coverings exposed in corridors or exitways, giving code officials one measurable basis for estimating flame-propagation behavior. That’s a deliberately narrow scope. Armstrong Flooring Commercial’s technical guidance notes explicitly that numerical ratings from this test do not predict total fire performance under actual fire conditions, and that resilient flooring products may in some cases be exempt from certain model-code flammability provisions even while an AHJ still requests documentation. USDA Forest Products Laboratory’s 2022 chapter on flammability test regulation (Hasburgh et al.) situates E648 alongside other radiant-flux methods used specifically for floor coverings, distinct from the vertical-surface tests used for walls and ceilings.

Healthcare facilities are a common trigger point: corridors serving patient care areas frequently carry a Class I requirement regardless of the general-area classification elsewhere in the building, which means the same product line may need documentation for both Class I and Class II uses on a single project.

ASTM E84/UL 723: Class A, B, C Interior-Finish Ratings, and Why They Don’t Substitute for E648

ASTM E84, also published as UL 723, classifies interior finish materials into Class A, B, or C based on flame-spread index and smoke-developed index measured in the Steiner Tunnel test. It applies primarily to wall and ceiling finishes and is referenced separately from floor-covering requirements in most model codes.

The International Code Council’s “Interior Finishes” material, which reproduces these ranges in the context of IBC commercial provisions, applies this classification system to interior finish materials generally, not to floor coverings specifically. Floor coverings are addressed under their own code sections and their own test method, ASTM E648. A vendor submittal that lists only an E84 Class A result in response to a corridor floor-covering requirement has not answered the question the code official asked.

Structural Fire Resistance Is a Separate Question: ASTM E119 and UL 263

ASTM E119 and UL 263 test complete floor-ceiling assemblies, composite decks, and fire-rated structural systems for how long they resist fire exposure and heat transfer, typically reported in hours. This is a structural fire-resistance rating for the building assembly, entirely separate from the surface-level performance of a floor covering or interior finish.

A concrete slab-on-grade with no fire-rated floor-ceiling assembly above or below it isn’t “unrated” in a deficient sense; it simply isn’t the subject of an E119/UL 263 test unless the project design calls for a fire separation at that location, such as a floor separating occupancies in a multi-story building. Confusing a Class I floor-covering rating with an E119 assembly rating is the single most consequential version of the three-category error, because it can surface late in a project when a code official or insurer asks for assembly documentation that was never generated. If your project includes any fire-rated floor-ceiling assembly, coordinate that listing early with the structural engineer and the assembly manufacturer, separate from and before finalizing the floor-covering submittal.

Canadian Requirements: CAN/ULC-S102.2 and the National/Provincial Building Codes

In Canada, flooring, floor coverings, and related assemblies are tested under CAN/ULC-S102.2, a companion standard to CAN/ULC-S102, and results are reported as Flame Spread (FS) and Smoke Development (SD) values specific to the tested product. UL Canada identifies both standards as the applicable methods for surface burning characteristics of building materials and flooring assemblies.

UL Canada’s methodology guidance describes the test as run in triplicate, with calibration reference materials illustrating the FS/SD scale: oak flooring reports at FS=100, SD=100, while noncombustible cement board reports at FS=0, SD=0. Every other product’s rating sits somewhere on that scale, and the number applies only to the exact assembly tested, not to the material category in general. The Canadian Wood Council’s 2020 publication “Surface Flammability and Flame-Spread Ratings” confirms that the National Building Code of Canada uses flame-spread ratings to quantify and compare surface flammability, and identifies CAN/ULC-S102.2 specifically as the method for flooring FS/SD ratings. British Columbia’s provincial building code publications (Appendix D, Division B) tabulate flame-spread and smoke-developed classifications tied directly to CAN/ULC-S102/S102.2, showing how these lab results get incorporated into enforceable code tables at the provincial level.

For cross-border projects, don’t assume a U.S. E648 Class I report satisfies a Canadian AHJ, or vice versa. Request the specific standard your jurisdiction enforces, not the closest equivalent.

Rating Requirements by Flooring Material Type

This is where the abstract three-category distinction becomes a concrete documentation problem, because the correct test method and the variables that can invalidate a prior result change by material family. A rating from a manufacturer’s general product line does not automatically apply to your specific installed system, which includes backing, adhesive, substrate prep, and often a cushion or underlayment layer that the lab report was actually testing.

Carpet and Carpet Tile

Carpet and carpet tile are evaluated under ASTM E648/NFPA 253 for Class I or Class II critical radiant flux (U.S.) or CAN/ULC-S102.2 for FS/SD (Canada). Results shift with backing type, cushion or pad, seam treatment, and adhesive; a test report generated for glue-down installation does not cover a cushion-backed or double-stick alternative. Request the manufacturer’s test report for the exact face fiber, backing, and installation method specified, not a generic product-line rating.

Resilient Flooring (LVT, VCT, Sheet Vinyl, Linoleum)

Resilient flooring is tested under ASTM E648/NFPA 253 in the U.S. and CAN/ULC-S102.2 in Canada. Armstrong Flooring Commercial’s Standards FAQs note that some resilient products may be exempt from certain model-code flammability provisions, but an AHJ can still request fire-performance documentation regardless of exemption status. Adhesive type and substrate can affect results; confirm the report covers the specific adhesive system in your spec.

Wood and Engineered Wood Flooring

Wood and engineered wood flooring fall under ASTM E648/NFPA 253 for critical radiant flux (U.S.) and CAN/ULC-S102.2 for FS/SD (Canada), with oak flooring serving as a UL Canada calibration reference at FS=100, SD=100. Finish type, wear-layer thickness, backing, and adhesive all affect the tested result, so request documentation matched to the specific finish system and installation method, not the raw species.

Concrete, Terrazzo, and Tile

Concrete, terrazzo, and ceramic or stone tile are generally noncombustible at the wearing surface, but fire performance of the installed system depends on sealers, coatings, adhesives, mortars, grout, and any underlayment beneath the visible surface, not the substrate alone. Request documentation covering the full installed system, since a bare-material claim about “concrete” or “tile” tells a code official nothing about the coating or setting system actually specified.

Resinous and Seamless Flooring

Resinous and seamless systems (epoxy, polyaspartic, MMA, polyurethane cement) are evaluated as complete installed systems, and results depend on resin chemistry, primer, aggregate broadcast, topcoat, and substrate. A rating for one resin formulation does not extend to a different topcoat or aggregate loading from the same manufacturer; request the test report for the exact system build specified, layer by layer.

Rubber Flooring

Rubber flooring is tested under ASTM E648/NFPA 253 (U.S.) or CAN/ULC-S102.2 (Canada), with results affected by adhesive selection, backing, and installed thickness. As with resilient flooring, request the report tied to the specific adhesive and installation detail in the project spec, since substituting adhesives is a common and easily overlooked source of an invalid submittal.

Raised-Access Floors

Raised-access floor systems present the highest documentation risk in this list, because performance depends on the complete assembly, panels, pedestals, stringers, adhesives, and underfloor components, not a surface test run on a detachable finish tile alone. A fire-performance report covering only the top laminate or finish layer says nothing about the panel core, the pedestal system, or the underfloor plenum configuration actually installed. Request assembly-level documentation, not a component-level test report, whenever raised-access flooring is part of the specification.

A Specification Workflow: How to Document Fire Performance Correctly

Getting fire-performance documentation right on a commercial flooring package means separating the three test categories early and confirming every report matches the exact installed system, not a generic product claim. The following eight-step sequence, drawn from the code and standards references above, gives specifiers a repeatable review order.

1. Identify the governing code (IBC, NFPA, or the National Building Code of Canada/provincial code) for the jurisdiction.
2. Classify the location: corridor, exitway, healthcare corridor, or general area, since thresholds differ by location.
3. Separate the three performance categories: floor-covering flame propagation, interior-finish flame spread/smoke, and structural fire resistance. Do not let one report answer for another.
4. Confirm the correct test method and required classification threshold for each category that actually applies to your scope (E648/NFPA 253, E84/UL 723, E119/UL 263, or CAN/ULC-S102.2).
5. Request system-level documentation matched to the exact backing, adhesive, cushion, coating, or assembly components specified, not a generic material-family claim.
6. Check for substitution errors: confirm no one has offered an E84 Class A result in place of an E648 Class I requirement, or a component-level test in place of an assembly-level test.
7. Coordinate any fire-rated floor-ceiling assembly listing with the structural engineer and assembly manufacturer separately from the floor-covering submittal.
8. Submit the complete documentation package to the AHJ for review before installation, and retain reports for warranty and insurance records.