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Fire Testing of Flat Roofing Products


Further to recent queries that have been raised within our market sector, we would like to clarify what the UK fire ratings for flat roofs mean.

  • Flat roofs are tested as a complete build-up of the roof structure

  • T4 is the only accepted test in the UK (e.g. BROOF(t4))

  • BROOF(t1), BROOF(t2), & BROOF(t3) are not accepted in the UK

The flat roofing industry is experiencing an influx of EPDM roofing systems that don’t comply with the requirements of the Building Regulations and legislation for roof coverings. These have either not undergone testing, or have not been tested to the UK standard TS 1187 Test 4 in accordance with BS EN 13501-5.

When designing a flat roof to withstand fire, the regulations are clear. It shall "adequately resist the spread of fire over the roof and from one building to another, having regard to the use and position of the building". The only way to ensure an installation is safe is by using a roof covering, including the roof build-up, has been appropriately tested to prove its performance is acceptable and legally compliant for use in the UK.

High demand & problems sourcing building materials has resulted in some suppliers, often with the best of intentions, seeking alternative manufacturers who only have testing for some European countries.

Suppliers and resellers of these products run the risk of falling foul of the Office for Product Safety in its new role as regulator for construction products, established under the Building Safety Act following the Grenfell tragedy. This could result in a prosecution or even a product recall and the subsequent impact this will have on those in the supply chain.

The rules

The Building Regulations 2010 set standards for the design and construction of buildings to ensure the safety and health of people in or about those buildings. In the 2019 update, the standard BS EN 13501-5 was cited as the principal determinant of external fire performance for roofs. This requires tests to be carried out in accordance with the document DD CEN/TS 1187:2012, which defines four test methods for the fire performance of roof covering systems in response to the legislation in place within different EU countries: t1 for Germany, t2 for Scandinavia, t3 for France, and t4 for the UK.

Defining the tests

The test methods vary significantly for different countries: Test t1 is with burning brands, for t2 it is with burning brands and wind, for t3 it is with burning brands, wind and supplementary radiant heat, while t4 is a two-stage evaluation of the fire performance of a roof with burning brands, wind and radiant heat. Importantly: t4 is the only test method that complies with the UK requirements for the Building Regulations and legislation for roof coverings.

 Results from the UK t4 test from are given as five ratings: BROOF(t4) is the highest possible class rating, FROOF(t4) is the lowest. If a roof system is classified BROOF(t4), it means the tests have shown that there will be no fire penetration of the roof system within 60 minutes. By comparison, a roof system classified FROOF(t4) is of the duration that the testing house is unable to determine its performance.


Class distinction

Clearly specifying a BROOF(t4) roof covering, tested appropriately, will ensure a flat roof has the highest performing covering, whatever the distance from the boundary. Specifying this classification for all flat roofs on a project will also help eliminate errors occurring on site.

It is only through understanding the importance of testing and the differentiation between the test codes, that specifiers, suppliers, building owners and contractors will be able maintain the safety and quality of product used and how they interact with different roof build ups.

Grenfell means there is now a greater understanding of how small changes to material specifications can have a significant impact on fire safety. It is important, therefore, that the correct product is specified and it is equally important that those installing the roof covering are vigilant in ensuring it has the appropriate certification for use in the UK to ensure the safety of all building users.

* NB: information provided from our suppliers via generalised email relating to their products. Some information may not apply but provided for customers perusal.

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