Fire Ratings Explained: EN 13501, ISO 11925 and B-s1,d0
Fire codes on spec sheets can look like secret writing. "B-s1,d0" is a good example. It is easy to read once you know the pattern.
The main letter
The European standard EN 13501-1 sorts products into classes by how much they add to a fire:
- A1 and A2: non-combustible or almost.
- B, C, D: combustible, with B adding the least.
- E and F: poor or untested.
The smoke tag
- s1: very little smoke.
- s2: medium smoke.
- s3: a lot of smoke.
The droplet tag
- d0: no burning drops.
- d1: some.
- d2: a lot. So B-s1,d0 means limited contribution to fire, very low smoke, and no burning drops.
How is the class decided?
Mainly through two tests.
- Single Burning Item test (EN 13823). A gas burner is lit against a corner made of two panels. Instruments measure heat, fire growth and smoke over ten minutes.
- Small flame test (ISO 11925-2). A small flame touches the surface or the edge for 30 seconds. The flame must not spread past 150 mm within 60 seconds.
BIOMEBOARD™ results
Both tests were done by Spectro Analytical Labs (Eurofins) on a 16 mm Type F board.
- Fire growth index: 38.4 W/s (the class B limit is 120)
- Smoke growth rate: 1.14 (limit 30)
- Total smoke: 28.6 square metres (limit 50)
- Burning drops: none
- Small flame test: flame stopped at 30 to 40 mm, with no burning drips The classification is B-s1,d0.
What this does not mean
- The board is not non-combustible.
- It is not a fire resistance rating. That is a different test (EN 13501-2) that measures how long a wall or door holds back fire.
- The result is for the board tested. Other thicknesses and the Type R surface have not been tested, and the class does not automatically carry over to a different set-up.
Reaction to fire vs fire resistance
These two are often mixed up.
- Reaction to fire (EN 13501-1) asks how much a material adds to a fire and how much smoke it gives off. B-s1,d0 is this type.
- Fire resistance (EN 13501-2) asks how long a wall, door or floor holds back fire and heat. This is measured in minutes, such as 30, 60 or 120. A board can have a good reaction to fire class and still not make a fire-resistant wall by itself.
A tip for reading spec sheets
Always look for four things: the test standard, the report number, the lab, and the exact product tested. If any is missing, ask.
FAQs
What does B-s1,d0 mean?
Limited contribution to fire, very low smoke, no burning drops.
Is class B good?
Yes, it is a strong result for an interior board.
Is class B the same as fire resistant?
No. Reaction to fire and fire resistance are different tests.
Does BIOMEBOARD™ have class B for all thicknesses?
Only 16 mm Type F has been tested so far.
What is FIGRA?
It is the fire growth rate index. It shows how fast a fire grows on the material. Lower is better.
Where can I see the report?
Request it and we will send it.