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. 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.
