+86 180 1863 2298 service@pulomax.com
A tender lands with two fire clauses on the same ceiling schedule: "Class A to ASTM E84" from the US consultant, "A2-s1,d0 to EN 13501-1" from the European architect. Both are valid. Neither one converts into the other, and no supplier can swap one report for the other.
Here is what each system measures, how to read the numbers, and which papers to demand before you sign off a submittal.
A ceiling board fire rating is how a board behaves when a flame hits it, measured by one fixed test. Both standards describe this as reaction to fire. They differ in method, units and grading logic.
One product line can carry both, because both tests can be run on the same board.
A 7.3 m (24 ft) sample is mounted in the ceiling position of the 7.6 m (25 ft) Steiner Tunnel and exposed to a controlled flame for 10 minutes. Technicians time the flame front as it travels the length of the board, and a photometer in the exhaust duct measures smoke density. Both readings are converted into indices against two calibration materials: inorganic fibre cement board = 0 and red oak = 100. The output is a Flame Spread Index (FSI) and a Smoke Developed Index (SDI).
The indices are relative, not absolute. They tell you how a board compares with red oak under one fixed set of conditions, which is why an E84 report is always issued for one specific product at one specific thickness.
| Class A | 0 – 25 | ≤ 450 |
| Class B | 26 – 75 | ≤ 450 |
| Class C | 76 – 200 | ≤ 450 |
One detail most articles miss: the 450 smoke limit covers general interior use. When the ceiling cavity is used as a return-air plenum, Class A material must also meet SDI ≤ 50.
IBC (International Building Code) Section 803 sets interior finish requirements by occupancy. Corridors, exit enclosures, and Assembly, Educational and institutional spaces are normally Class A. Lower-risk rooms can accept Class B or C. Confirm against the code version adopted for the project.
A1 means non-combustible with no calorific contribution. A2 means limited contribution. B to D describe decreasing resistance to flashover; E resists a small flame for a short period; F means no performance declared. A1 and A2 rest on EN ISO 1182 and EN ISO 1716, while B to F use the SBI test (Single Burning Item, EN 13823) and the small-flame test (EN ISO 11925-2).
The scale is finer than the US one for a reason. The SBI test measures heat release rate and total heat release in a room-corner configuration, so it can separate a board that contributes very little from one that contributes a little more. Two products sold as "Class A" in the US can land in different Euroclasses.
s1 is very low smoke, s2 medium, s3 high. d0 means no flaming droplets, d1 limited, d2 heavy. Both suffixes come from extra measurements taken during the same SBI test.
A2-s1,d0 means the board makes a limited contribution to fire (A2), produces very little smoke (s1), and releases no flaming droplets within the test period (d0). It is the typical classification for finished mineral wool ceiling boards in commercial buildings.
| Apparatus | Steiner Tunnel, 7.6 m | SBI room corner, 1.5 m |
| Result | Two indices: FSI, SDI | One class code plus suffixes |
| Smoke data | SDI as a number | s1–s3 as a band |
| Droplet data | Not reported | d0–d2 |
| Typical mineral wool board | Class A, FSI ≤ 25 | A2-s1,d0 |
The two systems answer different questions with different tolerances. A Class A result gives you a flame spread number from a tunnel; A2 gives you a contribution band from a room-corner scenario. No report can be converted, substituted or "upgraded" on paper.
This matters most in mixed-consultant tenders, where a European architect writes A2-s1,d0 and a US fire engineer accepts "Class A or equivalent". The word "equivalent" is doing a lot of work. Satisfy the clause by submitting the report that the named standard requires, not the one you happen to have.
Rock wool fibre melts above 1000°C, and the inorganic fibre structure has nothing to feed a flame. That is why mineral wool clears the non-combustibility route more easily than foam or paper-faced gypsum. To see how the fibre is formed, read what mineral wool ceiling boards are made of.
Be precise, though. A finished board contains a small share of starch binder and cellulose, so the tested product is normally A2-s1,d0, not A1. An A1 claim usually refers to a bare core or one specific tested build. Fiberglass ceiling boards follow the same pattern.
1. Reaction to fire is not fire resistance. Class A or A2-s1,d0 describes the board. A 1-hour or 2-hour rating describes the whole ceiling system — board, grid, hangers and fixings — tested to UL 263 or EN 13501-2. Swapping the board alone does not change the system rating.
2. Decide which standard governs. Follow the project location and the consultant's specification. If both appear, the board must satisfy both, with a report for each. Write the requirement into your purchase order as a clause with the standard number, the class and the required report — not as "fire rated tiles".
3. Request three documents.
Check that the product name and thickness on the report match the goods you are buying; a report for a 15 mm board does not cover a 12 mm board.
Last year a distributor in Rotterdam ordered Class A tiles on the strength of a "fireproof" brochure line. The tiles were fine; the paperwork was not. His submittal stalled for six weeks until an E84 report and a classification certificate arrived. Documents move projects, not adjectives.
Fire class also says nothing about acoustics. Absorption and attenuation are separate measurements, explained in our NRC vs CAC guide.
Does ASTM E84 Class A equal EN 13501-1 A1?
No. The tests, units and grading logic differ, so reports are not interchangeable.
What does A2-s1,d0 mean?
Limited contribution to fire, very low smoke, and no flaming droplets.
Are mineral wool ceiling tiles fireproof?
No material is fireproof. Mineral wool fibre is non-combustible, and boards typically reach Class A and A2-s1,d0.
What is the difference between reaction to fire and fire resistance?
Reaction to fire describes the board (E84, EN 13501-1). Fire resistance describes a complete system to a time rating (UL 263, EN 13501-2).
Which smoke limit applies to Class A ceiling tiles?
SDI ≤ 450 for general use, and SDI ≤ 50 where the ceiling cavity is a return-air plenum.
Which documents should a supplier provide?
An E84 test report, an EN 13501-1 classification certificate, and a DoP for EU deliveries.
Two standards, one decision. Match the ceiling board fire rating to the project, read the numbers rather than the marketing claims, and keep both reports on file. Treat any offer to convert one class into another as a warning sign.
Browse our mineral fiber ceiling tile range to see which boards carry these classifications. We can share our ASTM E84 test report and EN 13501-1 classification for your project, together with the DoP your consultant will ask for.
---