What is the BS 8414 test that’s talked about so much?
BS 8414 was first published as a British Standard in 2002, and was developed as a testing framework to assess the fire safety of cladding applied to the external face of a building. For obvious reasons, it has become much more widely talked about since the Grenfell tragedy of 2017.
BS 8414 would ideally be used to test the suitability of materials prior to use on buildings. However, in the wake of Grenfell, it has been applied much more to existing materials on buildings, some of which have been in place for decades. As the UK comes to grips with the scale of the unsafe-cladding crisis, BS 8414 is right at the heart of the widespread assessment taking place.
British Standard 8414 essentially sets out the standard for conducting a test to determine the safety of a material. The criteria that actually determines whether a material is safe or not is set out in BR 135:Fire performance of external thermal insulation for walls of multi storey buildings, which sets out the principles, design methodologies and fire spread performance characteristics for non-loadbearing cladding systems. Therefore, a BS 8414 test is carried outto establish conformity with BR 135 standards.
British Standard 8414 essentially sets out the standard for conducting a test to determine the safety of a material. A BS 8414 test is carried out to establish conformity with BR 135 standards.
How is the BS 8414 test carried out?
BS 8414 tests are carried out by certified testing laboratories on full-scale systems.
The BS 8414 test rig is essentially comprised of a steel frame, approximately 10m tall, with a large, recessed area at the bottom (like an oversized fireplace), called the combustion chamber. The cladding system to be tested is installed on the steel frame up to the full height, to create an authentic ‘wall’ of the material. A wooden ‘crib’, 1m x 1m x 1.5m, is then placed within the combustion chamber and lit. Thermocouples (temperature measuring sensors) are placed at three levels up the wall – 2.5m, 5m and 7.5m –and when the temperature reaches 200°Cat 2.5m height, the test begins. The fire is left to burn for 30 minutes and then extinguished, and a period follows where the wall is observed for any signs of residual burning or fire spread still occurring.
During the test, data is recorded, and this is conveyed in a subsequent report along with photos during and after the test. The test is measured against the BR 135 standard, which is based on flame spread criteria and mechanical performance, and the material is then awarded a BR 135classification which confirms whether or not it meets the requirements.
A BS 8414 test in action can be viewed here.
Is BS 8414 still fit for purpose?
Questions have been raised about the effectiveness of the BS8414 test and BR 135 criteria, and both have been made more stringent since Grenfell. In addition to this, the UK government has gone further than the requirements of BS 8414 / BR 135 by banning outright the use of combustible materials on the outside of any residential buildings over 18m that are built or refurbished after February 2019. The Government has, however, said that they still view the BS 8414 test as sufficient.