Written Question·Ministry of Housing, Communities and Local Government·UIN 92841
Building Regulations: Energy
Tabled: 19 November 2025
Answered: 28 November 2025
Question
Gideon Amos
Liberal Democrat — Taunton and Wellington
To ask the Secretary of State for Housing, Communities and Local Government, whether he has made an assessment of the potential merits of clarifying whether regulation 25A of the Building Regulations that relates to Approved Document L includes extensions where the new wall or roof area adds 25% to the surface area of the building.
Answer
Samantha DixonRegulation 25A of the Building Regulations 2010 concerns the use of high-efficiency alternative systems in new buildings and does not apply to extensions.
The energy efficiency standards that apply to extensions to existing dwellings are set out in Approved Document L: Conservation of fuel and power, Volume 1 (dwellings), Section 10.