ROOFING


DON’T IMPORT A PROBLEM


Buying roofing products sourced from outside the UK? Then you need to ensure they have the correct fire test certification to comply with the Building Regulations warns Ben Midwinter, Technical Director at Flex-R


H


igh demand and raw material shortages have left some


construction material manufacturers unable to fulfil orders. As a short- term solution, some suppliers have sought out alternative manufacturers, often from outside the UK. The problem with this is that not all imported flat roof coverings are tested equally and some may underperform in a fire, putting lives at risk.


The only way to ensure an installation is safe is by establishing that a roof covering has been tested appropriately and that its performance is legally compliant and acceptable for use in the UK.


To understand why the fire performance tests for flat roofs can vary across Europe, it is helpful to know a bit of background...


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. The Regulations require the roof of a building to “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”.


To accompany the Building Regulations, the government published a series of documents that provide guidance on ways to comply with the requirements of the regulations for common building situations.


Approved Document B (AD B) provides guidance relating to fire safety, it is in two parts Volume 1: Dwellings and Volume 2: Buildings other than dwellings. The 2019 edition of AD B included some major changes to Requirement B4, which relates to the classification of a flat roof system when exposed to fire from an eternal source. For roofs specifically, the risk is that burning airborne material or heat from a nearby fire


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will cause the roof to ignite and then the fire to spread.


In previous editions of AD B, the European Classification system (set out in BS EN 13501- 4), ran alongside the National Classification System as defined in BS 476-3:2004. In the latest update, BS EN 13501-5 is now the principal determinant of external fire performance for roofs. The reference to BS 476-3:2004 has been largely removed although Scottish regulation Technical Handbooks refer to both standards. The change in standard means both a change in the testing and subsequent classification for the external fire performance of roof coverings. Under the change, tests must now be carried out according to DD CEN/TS 1187:2012. This defines four test methods for roof covering systems in response to the different legislation in place within different EU countries: t1 for Germany, t2 for Scandinavia, t3 for France, and t4 for the UK. The test is intended to replicate a real- life situation, so it is conducted on the full system build-up and not the individual components. It’s increasingly important when specifying a roof system to understand the fire


performance of every element, including the underlying structure and roof deck. Defining the different test levels The test methods vary as such: 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.


T4 tests external fire spread and penetration by fire. It is also the only test method that complies with the requirements of the Building Regulations and legislation for roof coverings used in the UK, so suppliers and contractors need to check that imported roof coverings have been tested using Test 4. Test results are given as European class ratings, using the standard BS EN 13501-5. Five ratings are used for roof coverings in the UK; they run from BROOF(t4), which is the highest possible class rating, to FROOF(t4), which 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 so bad that the testing house is unable to determine its performance.


Class distinction


The classifications are important because they dictate the minimum distances a roof covering can be used from the site boundary, depending on building type and use. A BROOF(t4) rated roof covering, for example, can be used anywhere on the roof. A roof covering with an FROOF (t4) classification can only be used on roofs over 20m from the boundary.


Clearly BROOF(t4) is the gold standard for the UK when it comes to the performance of flat roofs and fire; it means an EPDM roof covering, for example, can be used on roofs without restriction. Armed with this insight, merchants can take advantage of this as an opportunity to demonstrate knowledge and provide value to their customers by explaining the benefits of a BROOF(t4) certified system to ensure risk is minimised.


The Grenfell tragedy means there is now a greater understanding of how small changes to material specifications can have a significant impact on fire safety. Therefore, manufacturers and distributors should ensure products they supply have the correct test certificates; meanwhile roofing contractors and building owners need to be vigilant in ensuring the products used have the appropriate certification for use in the UK to ensure the safety of building users. BMJ


www.buildersmerchantsjournal.net January 2023


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