The first cladding system using PIR solid foam insulation has passed the Government’s stringent fire tests in the wake of London’s Grenfell disaster.
It is the second cladding system to pass the large-scale fire test giving the industry a clear insight into which systems meet Building Regulation performance guidance.
The latest test results now suggest that PIR insulation can be fitted to a high-rise building, but only when used with aluminium composite material cladding using a ‘limited combustibility’ (stone) filler.
So far no high-rise buildings have been registered with the Government as having this particular combination of materials.
The Government’s testing body is carrying out a total of six tests incorporating each of the three common types of aluminium cladding material panel, using either core filler materials of unmodified polyethylene (PE), fire retardant polyethylene, or limited combustibility mineral.
These are being tested in combination with two insulation materials – rigid polyisocyanurate (PIR) foam or non-combustible stone wool.
With just one more test result due in for what is the least combustible combination of elements a picture is now emerging of which cladding systems meet the Building Regulations.
| Cladding system tests | Result | 18m-plus buildings |
|---|---|---|
| ACM with unmodified polyethylene filler with PIR foam insulation | Failed | 82 |
| ACM with unmodified polyethylene filler with mineral wool insulation | Failed | 111 |
| ACM with a fire retardant polyethylene filler with PIR foam insulation | Failed | 13 |
| ACM with fire retardant polyethylene filler (FR) with mineral insulation | Passed | 13 |
| ACM with a limited combustibility filler (A2) with PIR foam insulation | Passed | 0 |
| ACM with a limited combustibility filler with mineral wool insulation | Not published | N/A |
These suggest that at least 206 buildings over 18m in height that have been reported to the Government will need to be reclad.
Unmodified polyethylene filled ACM cladding, like that used on the Grenfell tower, fails Building Regulation requirements.
An aluminium cladding system using fire retardent polyethylene filler (FR) could be used, but only when installed in conjunction with mineral wool insulation and not PIR foam board.
ACM cladding using limited combustibility filler (A2) can be used with PIR foam insulation boards.
A cladding industry source said: “These results must be welcomed because they bring some clarity to what systems comply with Building Regulation requirements.
“But the use of the terminology used by manufacturers around combustibility of fillers used in aluminium cladding needs to be addressed to end market confusion.”
Even with the latest test information the Government still advises that building owners need to continue to take professional advice regarding remedial work that takes into account the specific circumstances of their building.
The way materials have been fitted and maintained can also affect the safety of the cladding system.
Last month the government announced an independent review of building regulations and fire safety, focussed on the regulatory system around the design, construction and on-going management as well as related compliance and enforcement issues.
