Move comes as government gives councils power to strip cladding from private blocks

The use of cross-laminated timber in buildings taller than 18m looks set to be outlawed as the government reveals details of its combustible materials ban.

The amendment to Approved Document B, which was laid before parliament today, has ruled out the use of any material within an external wall that does not have one of the top combustibility ratings, A2-s1, d0 or Class A1, with the exception of membranes, seals and gaskets.

James Brokenshire in parliament on 30 April, 2018

Source: Parliament TV

Housing, communities and local government secretary James Brokenshire

The document defines an external wall as “anything located within any space forming part of the wall”.

The changes to both the Approved Document B and Section 7 of the building regulations not only cover residential towers that rise more than 18m above the ground, but will also need to be adhered to by those building student accommodation, care homes, sheltered housing, hospitals and dormitories in boarding schools.

While these changes could spell the end of CLT in resi towers, companies concerned about the ability to use rainscreen cladding systems when the ban came into effect have been heard, with the ban excluding membranes, seals, gaskets, fixings, sealants and backer rods.

Doors, windows and their frames are also exempt from meeting the combustibility rating requirements.

The new regulations mean that only the European classification class A2-s1, d0 or class A1 will be acceptable and that materials achieving limited combustibility cannot be deemed to meet the requirement using an alternative classification method.

Local authorities have also been given the power to remove and replace unsafe cladding on private buildings, with housing secretary James Brokenshire saying local authorities will get the government’s full backing, including financial support if necessary, to enable them to carry out emergency work on affected private residential buildings with unsafe ACM cladding.

The local authorities will then be required to recover the costs from building owners.

Brokenshire said: “Everyone has a right to feel safe in their homes and I have repeatedly made clear that building owners and developers must replace dangerous ACM cladding. And the costs must not be passed on to leaseholders.

“My message is clear. Private building owners must pay for this work now or they should expect to pay more later.”

The government is already fully funding the replacement of unsafe ACM cladding on social sector buildings above 18m.