Class "0" - What Does it Mean?

The Building Regulations Approved document B is very clear about the technical requirements for housing of multiple occupancy. The intention is for internal linings of communal areas to conform to Class "0".

Extract: from Building Regulations Approved Document B:

"The Requirements

Internal fire spread (linings)

B2.






Classification of Performance

The main classifications used are based on tests in BS476 Fire tests on building materials and structures, namely Part 6: Method of test for fire propagation for products and Part 7: Method of test to determine the classification of the surface spread of flame of products.

At the design stage it is sufficient for the selected products to have achieved a Class 0 rating over a non-combustible surface, i.e. skimmed plasterboard. However, many coatings that are Class 0 on a non-combustible substrate will not perform to Class 0 when applied over several layers of paint.

Warrington Fire Research Centre therefore provides a specially prepared board for testing for a redecoration application. This board, known as the Warrington Fire Research Centre "Blue" board is constructed using ten coats of different types of oil-based paints in order to simulate a previously decorated surface.

This means that products can now be tested over the "blue" board to achieve a Class 0 rating for use in multi-layer paint scenarios.

It is therefore important that Fire Test Reports be requested and checked to ensure that it is consistent with the intended use of the coating.