Remedial actions to external wall systems (EWSs) are being advised for many residential blocks that fall below the 18m building-height threshold. 

Shaun Harris

Shaun Harris

One of the key reasons for this can be the failure of EWSs to satisfy Building Regulations approved document requirement B4. Requirement B4 requires that “the external walls of the building shall adequately resist the spread of fire over the walls and from one building to another, having regard to the height, use and location of the building.”

In 2019 and in 2020, the MHCLG raised concerns that consideration is not routinely given to requirement B4 nor the intent of B4 being sufficiently assessed, particularly in circumstances where the guidance in approved document B is less specific, including for buildings that are sub-18m. The MHCLG acknowledged that the use of combustible materials within or attached to the EWSs of sub-18m buildings is not expressly prohibited either by Building Regulations or the approved documents, but noted it is still necessary to consider the health-and-safety risk in these buildings from fire spread.

This is why sub-18m blocks are so exposed, specifically where insufficient attention was paid to B4 during the design, construction, monitoring and signing-off stages. For many sub-18m blocks, façade risk assessments are flagging up that, from the standpoint of fire safety, B4 has not and could not have been satisfied.

The scale of this sub-18m challenge should not be underestimated. Part of the government response has been to announce the cladding remediation loan scheme, to be set up specifically to assist leaseholders in funding necessary remediation work. But it will still require leaseholders to pay, be that via a long-term loan or by some other means.

Whether that is equitable is perhaps a discussion for another day, but be under no illusions: this challenge has only just begun. Assessments, claims, counter claims, evidencing, expert opinion and even a dollop of doing the right thing are all going to play their part before this is over.

Shaun Harris is managing director of Harris Associates