Last year, I wrote an article commenting on the fact that the 2020 editions of the Domestic and Non-Domestic Technical Handbooks (official guidance for compliance with the Building (Scotland) Regulations 2004 (the "Regulations")) had removed direct reference to a party's ability to demonstrate "alternative" compliance with the Regulations by using a solution reliant on BS 8414/BR135.

At that time, it was still possible for applicants to use the BS 8414/BR135 route if they applied to do so, but I queried whether the removal of a direct reference in the Handbooks might be the first step towards the removal of the "alternative" route all together. In publishing The Building (Scotland) Amendment Regulations 2022, which will amend the Regulations, the Scottish Government have confirmed that is indeed their intention and that only strict compliance will now be acceptable.

Tighter controls on materials

When the amendments take effect, the Regulations will require that any materials which "form part of an external wall cladding system… are of European Classification A2-s1, d0 or A1, classified in accordance with BS EN 13501-1:2018". These restrictions will apply to all high rise domestic and other high-risk buildings (such as hospitals and care home). In Scotland the term "high-rise" applies to any building which is 11m or taller (rather than the 18m figure used elsewhere in the UK).

Previously, cladding systems could avoid the need for strict compliance with this requirement if they had passed a large-scale fire test in terms of BS 8414. This meant that it was possible for combustible materials to be used in an external walling system, provided that the system as a whole passed the test. However, this loophole has now been closed.

Ban on metal composite materials

The amendments to the Regulations also contain an outright prohibition on the use of "highly combustible metal composite material" in the construction or refurbishment of buildings of any height. This is a ban on what has been referred to as "Grenfell style" cladding, which comprises panels made up of two metal sheets and a filler core. If that core has a "gross calorific value of more than 35 MJ/kg", then it can no longer be used on projects in Scotland. The "gross calorific value" essentially demonstrates how much that material would contribute to fire. As a comparator, the calorific value of diesel is around 45 MJ/kg and dry firewood is around 16MJ/kg.

There have, however, been suggestions that this prohibition does not go far enough in banning dangerous materials. Critics argue that in limiting the ban to only the "worst" class of metal composite materials, an opportunity to provide wider protection has been missed. The ban is also specific to metal composite materials and other potentially hazardous materials, such as high pressure laminate (HPL) materials do not fall within the terms of the ban.

Time will tell whether, as with the limitation of combustible cladding on high rise properties, these restrictions will tighten over time.

What next?

  • The amended Regulations will take effect for all projects where Building Warrant is applied for on or after 1 June 2022.
  • New versions of the Domestic and Non-Domestic Technical reflecting the new regime will be published in early May.


Eric Johnstone

Legal Director