Fire test establishes flammability of core material used in ACM cladding panels

The BRE has released details of the tests being used to establish the flammability of external cladding on local authority tower blocks which it is carrying out on behalf of the communities department.

The government ordered safety checks on the cladding used on local authority tower blocks after the Grenfell Tower fire where fire spread rapidly up the outside of the building.

The tests are being carried out on buildings that are suspected of being clad with aluminium composite material (ACM) panels. ACM panels feature two thin aluminium skins sandwiching a cheaper core material that gives the panel its rigidity and keeps costs down.

The panels used for the external rainscreen on Grenfell Tower were a product called Reynobond which features a plastic core.

The cladding has been tested on 120 blocks, and results so far show a 100% failure rate. Up to 600 blocks could be tested.

The test was devised by an independent panel of experts on behalf of the communities department and performed on the core of test samples after the external aluminium skin had been removed from the panel.

The test has 3 categories with a category 2 or 3 rating deemed by the expert panel to fail the combustibility standards in Part B, the building regulation covering fire.

Peter Bonfield, chief executive of the BRE, said the tests had been performed on ACM panels from a number of manufacturers and all had failed the test.

The test is performed using a device called a bomb calorimeter where the sample is heated in an enclosed container with the energy given off by the sample measured by the device. There are four to five test devices in the UK which have been calibrated by the BRE to give consistent results.

There have been suggestions the test process is taking too long. However Bonfield said up to 100 samples could be tested a day. He said: “We respond to the samples that we get in. The demand has been increasing.

Bonfield has been appointed to an advisory panel by communities secretary Sajid Javid to advise on measures to be put in following the Grenfell fire.

The panel also includes Amanda Clack, EY partner and president of the Royal Institution of Chartered Surveyors, and Roy Wilsher, chair of the National Fire Chiefs Council. It will be chaired by Sir Ken Knight, former government chief fire and rescue adviser.

The first meeting takes place tomorrow.