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External Wall Insulation – Compliance with Approved Document B – Fire Regulations

manchester ewi high-rise

There is still a lot of confusion regarding what testing and accreditations External Wall Insulation (EWI) systems need to comply with Building Regulations pertaining to fire on high-rise buildings. Here, Alumasc’s Technical Director, Mark Gibbs clarifies the situation.

Routes to compliance

For the use of EWI in high-rise constructions (i.e. buildings greater than 18 m in height), there are two routes to conformance with the requirements of Approved Document B to the Building Regulations 2010 (England and Wales) (as amended):

  1. Linear compliance – the insulation must be A1 non-combustible and the system be classified as A2-s3,d2 or better (when tested to BS13501-1 Fire classification of construction products and building elements — Part 1: Classification using data from reaction to fire tests); or
  2. BR135 route to compliance – typically used for systems which contain cladding or insulation materials which are not considered A1 or A2. Systems must be approved via a full-scale fire test to either BS8414-1 (masonry substrates) or BS8414-2 (steel framed substrates). This would be used for phenolic and EPS systems for example.

System Classifications

Alumasc’s Pro EWI systems – Silkolitt Pro, VBriQ Pro, Exicco Pro (drained cavity system) – comprise of A1-rated mineral wool insulation. These systems have been proven to achieve a limited combustibility classification of A2 (or more fully A2-s1,d0) when tested in accordance with BS13501-1:2007.

For systems that achieve this A2-s1 d0 classification, BS 8414 full-scale tests are not a requirement of Approved Document B to The Building Regulations 2010 (England and Wales) (as amended).

Where constructions do not achieve limited combustibility ratings (because they comprise insulations that, in isolation, are classed as combustible), full-scale fire tests must be conducted to demonstrate that the system is suitable for use. Indeed, Alumasc has a range of EPS and phenolic EWI systems that have passed full-scale BS 8414 tests when they have been encapsulated by non-combustible renders.

It remains to be seen whether regulations will continue to allow full-scale fire tests to approve the use of combustible materials in high-rise constructions. However, there has certainly been a recent trend for designers to avoid this requirement by specifying A1 or A2 rated systems.

For more information on Alumasc’s A2-fire rated Silkolitt Pro, VBriQ Pro & Exicco Pro systems as certified by the British Board of Agrément (BBA) without height restriction, please click here.