Planning permission and Building Regulations are two completely separate approvals, run by different parts of the council, with different requirements. Homeowners often think "I have planning, so I am sorted" — but Building Regulations is just as important, and many extensions need it even when planning is not required.
Planning permission: WHAT you are building
Planning permission is about whether your project is appropriate for the location — its size, appearance, impact on neighbours, and effect on the character of the area. It does not care whether the building is structurally sound.
Building Regulations: HOW you are building it
Building Regulations are about how the building is constructed — structural integrity, fire safety, insulation, drainage, ventilation, electrical safety. They are set out in the Approved Documents A–S published by the Department for Levelling Up, Housing and Communities (now Ministry of Housing, Communities and Local Government). The official documents are available at https://www.gov.uk/government/collections/approved-documents. Even a project that does not need planning permission almost always needs Building Regulations approval.
What Building Regulations cover
- Structural design (foundations, load-bearing walls, RSJ steel beams)
- Fire safety (smoke alarms, escape routes, fire doors)
- Insulation (walls, floor, roof, U-values)
- Drainage (foul water, surface water)
- Ventilation (extractor fans, trickle vents)
- Electrical safety (Part P compliance)
- Glazing (safety glass in critical locations)
- Stairs (rise, going, headroom)
How approval works
You typically choose between a Full Plans application (drawings approved before work starts) or a Building Notice (inspections during the build, no advance approval). Most extensions use Full Plans for the certainty it provides.
A Building Control officer (or an Approved Inspector) visits the site at key stages — foundations, drains, structural steel, insulation, completion — and issues a Completion Certificate at the end. This certificate is essential for resale.
What happens if you don't get Building Regulations approval
If you build an extension without Building Regulations approval:
- The council can serve an enforcement notice up to 12 months after completion
- You may be required to expose foundations, structural elements, and drainage for inspection
- In worst case, parts of the build may need to be demolished and rebuilt
- You will struggle to sell — buyers and their solicitors always ask for the Completion Certificate
- Your insurance may not cover problems related to the unauthorised build
How we handle this on every JCT project
Every extension and structural alteration we deliver includes:
- Structural engineer's calculations for steelwork and foundations
- Full Plans submission to your local council's Building Control
- Coordination of all Building Control inspections
- Certificates of compliance for gas, electrics, and energy performance
- Final Completion Certificate at handover
Want to understand what your project needs?
A free site visit lets us scope out what planning and Building Regulations approvals your project will need. Call 07769 225120.
