The government’s review of Approved Document B proposes a height threshold that would push structural timber out of buildings above 11m unless a full fire-engineered case is made. 

We are concerned that the proposals represent a retrograde step at precisely the moment the construction sector needs to be moving in the opposite direction. The reuse, retention and extension of existing buildings is recognised as one of the most significant and immediately deliverable levers available to reduce the built environment’s contribution to climate change. Structural timber is frequently the only practical structural choice for the lightweight extensions, roof-top additions and adaptations that make this reuse possible. A regulatory change that constrains timber risks closing off, or substantially increasing the cost of, one of the few practical routes to reuse rather than demolition. This would undermine the sector’s decarbonisation and housing delivery goals.  

Over the past 16 years, dwelling fire deaths have been in the low hundreds per annum. In comparison over 3,000 early deaths were attributed to extreme heat in 2022 and the Climate Change Committee predicts heat-related deaths exceeding 10,000 a year by 2050. We believe that an explicit comparison is required, so that the proportionality of restricting a key low-carbon structural material can be properly tested against the comparative scale of the two risks. 

Building reuse and adaptation is itself a critical climate mitigation strategy, and fire safety guidance for existing buildings should be drafted to enable rather than obstruct the use of structural timber in this context. A threshold or restriction that removes structural timber as a viable option above 11m, a height easily reached by a rooftop extension on an existing three- or four-storey building, would directly and disproportionately constrain exactly the kind of retrofit-led, low-carbon adaptation that the government recognises is needed.  

Fire safety matters enormously. Grenfell must never be repeated, but regulation must be proportionate and balance all of the risks it seeks to control.  

Download below and read tERC’s submitted formal response setting out the case in detail.