Planning permission and Building Regulations are separate approvals. An extension can be permitted development and still need Building Regulations approval, because the regulations are about whether the building work is safe, healthy and energy efficient, not whether it is acceptable in its setting.
What building control looks at
- Structure. Foundations, walls, floors, roof and any steel beams are checked against calculations, usually from a structural engineer.
- Fire safety. How the extension affects escape routes from the existing house, and how close it is to the boundary.
- Drainage. Where new drains connect, and any building over or near an existing drain or sewer.
- Damp and ground conditions. Damp-proofing and protection of the floor and walls from moisture.
- Energy. Insulation, windows and glazing, and the heating for the new space.
- Ventilation and electrics. Adequate ventilation, and electrical work that meets the safety requirements.
How it works in practice
- An application is made to your local authority’s building control or to a registered private approver, either with full plans or by a building notice.
- The work is inspected at key stages, such as when the foundations are dug and before they are covered, at damp-proof level, when drains are laid, and when the structure and insulation are in place.
- At the end a completion certificate is issued. Keep it: a buyer’s solicitor will ask for it when you sell.
Your builder normally arranges inspections, but it is your responsibility as the owner that the work is approved, so it helps to know the stages and ask which one is next.
Where this connects to other approvals
Steel beams and new openings usually need a structural engineer, and building up to a shared wall may need a party wall notice. For the difference between this and planning, see planning permission or Building Regulations.
This guide is general information for homes in England and is not legal or planning advice. Rules can change and differ between properties and local authorities, so always confirm the position with your council or a qualified professional.
See our house extension service, or request a quote.