In UK homes and commercial buildings, the roof is one of the main areas through which fire can spread. This is because most of our buildings are made from brick or stone which are naturally fire resistant, whereas most of our roofs contain a lot of wood and felt which burns much more easily.

If a fire does break out, it can quickly burn through a traditional roof before spreading to the roof of the next building and on and on. Having a roof that is more resistant to fire can therefore significantly reduce the impact of a fire in the unfortunate event that one breaks out.

External Fire Resistance

The resistance of a roof to fire is based on how well the roof prevents fire from penetrating its structure and spreading through it from the outside. The longer a roof prevents a fire entering the building and the more slowly it spreads, the more time people have to evacuate the building and the fire brigade have to respond and get the fire under control. Ultimately, the more fire resistant your roof is, the less chance of human harm and the less damage there is likely to be to the building.

British Standard 476 Fire Tests

In the UK, the fire resistance of buildings is established using a series of tests knowns as British Standard 476 Fire Tests. There is a specific test for roofs known as BS 476-3:2004 which establishes just how effective a given type of roofing is at resisting the penetration and spread of fire.

Fire Resistance Ratings

There are several parts to an external fire resistance rating. They tell you what kind of roof the rating applies to (sloping or flat) and how well it stands up to fire penetration and fire spreading. For an example rating of EXT.S.AA, the ‘EXT’ signifies that this is an external building material, the S indicates that this is a sloping roof (as opposed to F for a flat roof), the first A refers to the roof’s resistance to fire penetration and the second A to its resistance to fire spread.

Roofs are graded from A-D for the resistance to fire penetration and spread, with the letters meaning the following:

For fire penetration, each letter corresponds to how long it took a test fire to penetrate the roofing material:

A – More than an hour
B – From 30-60 minutes
C – From 0-30 minutes
D – Almost instantly

For fire spread, the letters show how far a test fire managed to spread through the roofing material during a 60 minute test:

A – No spread
B – 21 inches or less
C – More than 21 inches
D – A 15 inch spread almost instantly and/or the material continued to burn for 5 minutes after the flame was removed.

Get a fireproof roof with Metrotile

Metrotile’s steel roofing has achieved the UK’s highest external fire resistance rating for sloping roofs, EXT.S.AA. This means a Metrotile roof will provide a minimum of 1 hour of protection from external fires, giving plenty of time for safe evacuation and for emergency services to respond.

To find out more or to ask for a quote, call Metrotile today on 01249 658 514 or use our contact form for a swift response.