Planning & Permissions
Building regulations approval explained
How it's different from planning permission, and why you need both for some projects.
Building Regulations approval is separate from planning permission and covers whether work is built safely and to standard — structure, fire safety, insulation, ventilation and more — regardless of whether planning permission was needed in the first place. Most extensions, loft conversions and structural alterations need it.
Last updated 17 August 2026
Key points
- Planning permission is about whether you can build something; Building Regulations are about whether it's built properly.
- Permitted development work still generally needs Building Regulations approval.
- Approval can be sought via a full plans application (checked in advance) or a building notice (inspected as work progresses).
- You should end up with a completion certificate — keep it, since buyers' solicitors ask for it.
Planning permission vs Building Regulations
These are two entirely separate approval processes covering different things. Planning permission (or permitted development) is about whether a proposal is acceptable in principle — its size, position and impact on neighbours and the area. Building Regulations approval is about whether the finished work is structurally sound, safe and meets minimum performance standards.
It's entirely possible to need Building Regulations approval for work that didn't need planning permission at all — most permitted development extensions, for example, still need Building Regulations sign-off.
What Building Regulations actually cover
The regulations are organised into parts covering structure, fire safety, ventilation, drainage, electrical safety, thermal performance and more, each with an Approved Document setting out how to meet the requirement in practice.
For a typical extension or loft conversion, structure (steel beams, foundations), fire safety (escape routes, especially for a loft conversion), and thermal performance (insulation) tend to be the areas that need the most attention.
The approval process
You can apply via a full plans application, where detailed drawings are checked before work starts, or a building notice, where inspections happen at set stages as the work progresses rather than upfront. Both routes end with the same goal: a completion certificate confirming the finished work complies.
Keep that certificate. It's routinely requested by a buyer's solicitor if you sell the property later, and its absence can complicate a sale even for work that was actually done properly.
Take this further
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