What the classes really mean.

In Switzerland the fire protection ordinance of the Association of Cantonal Fire Insurance Companies, the VKF, applies. It prescribes which materials may be used where. In residential buildings, in public spaces, in high-rise buildings, in escape routes. The rules are clear. The language is not always.

The two systems.

Two classification systems are currently in use in Switzerland. The old VKF system with RF1, RF2, RF3, RF4 and the European system according to EN 13501-1 with classes such as A1, A2, B, C, D, E, F.

The VKF accepts both, but has switched to the European system for most applications. Those specifying today should work with the European classes.

What the European classes indicate.

The main class describes fire behaviour.

A1 is non-combustible. Concrete, stone, steel, mineral plasters.

A2 is non-combustible with a limited combustible component. Plasterboard, some mineral wools.

B is flame-retardant. High-quality wood-based panels, some plastics.

C, D, E are increasingly combustible.

F has no requirement for fire behaviour.

In addition, two further letters are used.

s stands for Smoke. s1 little smoke, s2 medium, s3 a lot.

d stands for Drops. d0 no burning droplets, d1 limited, d2 no requirement.

A complete classification looks like B-s1, d0. Flame-retardant, little smoke development, no burning droplets.

What is required where.

In escape routes and public spaces A2-s1, d0 is generally required. In dwellings the requirements are usually lower: B-s2, d0 is often sufficient. In high-rise buildings above a certain height stricter rules apply.

The exact requirements are set out in the VKF fire protection directive. When in doubt: consult the responsible fire protection specialist.

What matters when specifying.

Three points that regularly cause delays.

First: the certificate must be current. Fire classifications are re-certified every few years. A material that was certified B-s1 ten years ago is not automatically still so today.

Second: the classification applies to the tested construction. A wood panel tested in isolation has a different classification from the same panel on a combustible substrate.

Third: the classification applies to the specific product. A variant of the same collection added after certification is not automatically co-certified.

Working with current, structured data avoids disputes with clients, lead planners and the fire protection authority.