The government has widened its safety warnings about high-rise blocks following the Grenfell Tower fire by saying that a wide range of cladding systems could potentially fail fire testing, while others could possibly fall off in high winds.
In two separate pieces of advice aimed at councils and other owners, the communities department said they should carry out checks to some types of cladding and to external insulation involving render or brick-slip finishes. It is not known how many blocks might potentially need such checks.
In the wake of the Grenfell Tower fire in June, in which 71 people died, ministers ordered tests on external cladding systems using aluminium composite materials (ACM), after a failure was identified as a likely cause of the rapid spread of the blaze. Tests by the Building Research Establishment found that only a small minority of such ACM systems passed the necessary fire safety regulations.
In a new warning on Monday, the Department for Communities and Local Government (DCLG) says owners of high-rise blocks clad in a non-ACM system should seek to investigate whether these were properly fire safe. One problem could be the use of a cheaper substitute, as reportedly happened with Grenfell.
“The potential that there may be incorrectly specified or substituted products installed on tall buildings should not be ignored,” the guidance says. “Building owners will want to satisfy themselves and their residents that buildings are safe, and may therefore wish to carry out the checks.”
Owners are told to make sure the component parts pass fire safety standards and check records to make sure the systems were correctly installed and maintained.
The checks should cover the external rainscreen or render, and any associated insulation, the DCLG says, and should investigate whether “there is potential for a product to have been substituted from what was originally specified at the design stage”.
The department is asking fire test laboratories to release details of cladding systems and components they have checked and which of these have met the necessary safety standards.
A separate document urges other checks to be made on high-rise blocks with external insulation systems which use either a render or brick-slip, which involves slim pieces of brick-end covering the surface.
The DCLG said there had been some reports of such systems becoming “vulnerable to deterioration”, resulting in parts of the cladding falling from the building. There were no reports of injuries from such failures, but owners were told to make checks.
If such systems were installed wrongly, using insufficiently good adhesive or fittings, or if gaps allowed the cladding to become waterlogged and thus more heavy, they could detach in high winds, the guidance says, adding: “Due to the nature of the problems that have been identified, this advice is particularly relevant for tall buildings subject to high wind loading due to high wind speeds.”
Owners of buildings of 18m or above which use such external insulation have been told to examine the exteriors and check records to ensure they were fitted correctly.
A DCLG spokesman said the government had no figures of how many buildings could be affected with either fault. Earlier statistics said 173 high-rise social housing blocks had used ACM-type cladding.
