Fire Ratings for Ceiling Systems

Two different things both get called a "fire rating"

Most disputes on a submittal come from this one confusion, so it is worth settling first.

• Surface burning characteristics — how readily a material's surface carries flame, and how much smoke it makes doing so. This is what Class A, B and C refer to. It is measured by ASTM E84 (identical in method to UL 723 and NFPA 255), the Steiner tunnel test, which returns a Flame Spread Index and a Smoke Developed Index.
• Fire resistance — how long an assembly holds back fire and keeps carrying load. This is the hourly rating (1-hour, 2-hour) from ASTM E119 / UL 263, and it belongs to a whole assembly — a floor-ceiling or a rated corridor — not to a decorative component.

A Class A finish is not a one-hour assembly, and a one-hour assembly is not "Class A". If a specification asks for a fire-resistance rating, a surface burning report does not answer it. Attaching anything to the underside of a rated assembly can also affect that assembly, which is a question for the design professional of record, not for a product data sheet.

What the classes actually mean

Under ASTM E84, interior finish materials are grouped by Flame Spread Index (FSI). All three classes share the same smoke ceiling.

Note what the class does not tell you. It says nothing about toxicity, nothing about how the material behaves once fire is fully developed, and nothing about whether it drips. Those are separate questions, and on a sensitive occupancy an authority having jurisdiction may ask them.

Where the requirement lives in the code

Requirements come from the International Building Code (IBC), as adopted and amended by your state and then by your local jurisdiction. Two chapters matter for ceilings.

• IBC Chapter 8, Section 803 — Interior Finishes. This is where wall and ceiling finish materials are classified by ASTM E84 or UL 723, and where the table of required classes sits. The required class is not a property of the product; it is a function of the occupancy group (assembly, business, mercantile, institutional, residential) and where in the building the finish is — vertical exits and exit passageways are held to a higher class than corridors, and corridors higher than enclosed rooms. Sprinklered buildings are permitted a lower class in many rows than non-sprinklered ones.
• IBC Chapter 26 — Plastic. This is the one people miss. Foam plastic is not treated as an ordinary interior finish. Section 2603 governs foam plastic generally, and Section 2604, Interior Finish and Trim, governs foam plastic used decoratively. It sets limits beyond the flame spread class — on the material's density, on the thickness and width of a trim piece, and on the proportion of the total wall and ceiling area that foam trim may cover. A decorative polyurethane beam is foam plastic trim, so both chapters apply, and the Chapter 26 limits can be the binding constraint even when the flame spread class is satisfied.

Check the edition, not just the section number. Section and table numbers move between IBC editions — the interior finish table is Table 803.11 in the 2018 IBC and Table 803.13 in the 2021 IBC, with the same content. Cite the edition your jurisdiction has actually adopted.

What that means in the states we work in

• California amends the IBC into the California Building Code (CBC), Title 24, Part 2, on a three-year cycle with intervening supplements. Interior finish stays in CBC Chapter 8. California also runs the State Fire Marshal Building Materials Listing program, and for the product categories it covers a listing or registration number is what an inspector looks for, in addition to the test report. Ask early whether your project's materials fall inside it.
• Nevada and Arizona adopt IBC editions at the local level, so Reno, Washoe County, Phoenix and each Maricopa County municipality can be on different editions at the same time. There is no single statewide answer to quote.

In every case the authority having jurisdiction is the one that decides. A manufacturer, a supplier and a website can all be wrong about your building; the plans examiner cannot.

What a submittal actually needs

"It is Class A" is not a submittal. What gets approved is paperwork that ties a number to a tested product.

1. The test report — a report from an accredited laboratory, naming ASTM E84 or UL 723, stating the FSI and SDI, and identifying the exact material tested by name and formulation.
2. Confirmation that the product supplied is the product tested. A rating belongs to a formulation, not to a product family. A standard-formulation beam and a fire-rated-formulation beam are different materials even when they look identical.
3. Where applicable, the listing or registration under the state program.
4. The installation detail — what the piece is fixed to, with what adhesive and fasteners, and at what coverage. How a material is mounted can change how it behaves.

How we handle it

Our polyurethane products are available in a fire-rated formulation, and it has to be specified when the order is placed — it is a different material, not a coating applied later, so it cannot be added after the fact. That condition is set out in our terms and conditions of sale.

We do not publish a flame spread number for our products on this page. A rating means something only when it is the number on the report for the formulation you are actually buying, and it is our supplier's test data to issue. Ask us for the current test report for the formulation you are specifying and we will send it — before you commit it to a drawing, not after.

If your project has a fire requirement, tell us at inquiry stage rather than at order stage. It changes the material, the lead time and the price, and it is far cheaper to design around than to discover at inspection.

Send us the occupancy, the location within the building, whether it is sprinklered, and the code edition your jurisdiction is on, and we will tell you what we can supply against it — or say plainly that we cannot.

Related

• Commercial ceilings & interiors
• Commercial faux wood beam collection
• Trade & partner program — for specifiers
• All services & service areas
• Request a test report or a project review

Frequently asked questions