Building regulations for extensions

Almost every house extension needs building regulations approval, whether or not it needs planning permission. The regulations cover structure, fire safety, insulation, ventilation, drainage and more, and an inspector checks the work at key stages before issuing a completion certificate.

We prepare the building regulations drawings and specification, arrange the structural engineer's calculations, submit to building control and book the inspections during the build, so you receive the completion certificate at the end.

What is included

• Building regulations drawings and written specification
• Structural calculations for beams, lintels and foundations
• Energy and glazing checks, including whole-house calculations if needed
• Submission to the council or a registered building control approver
• Inspection bookings throughout the build
• Completion certificate on sign-off

Who it suits

• Every extension, whatever the planning route
• Homeowners using their own builder who need the drawings
• Glass-heavy designs that need energy calculations

Design advice

Building regulations approval and planning permission are separate. A design can have planning consent and still need changes to meet the regulations, which is why we draw for both together.

How much does it cost?

National guide prices including VAT at 20%. Your area page shows prices adjusted for your region.

Our design fee only. Building control charges are set by your council (or, in England and Wales, a registered building control approver) and quoted separately.

Building control across the UK

England

Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.

Wales

Building regulations approval is separate from planning. Wales has its own building regulations and approved documents; the council or a registered building control approver checks the plans, inspects the work and issues a completion certificate.

Scotland

In Scotland a building warrant from the council is needed before work starts on almost any extension, and a completion certificate is issued when the work is accepted. Building standards are set in the Scottish technical handbooks.

Northern Ireland

In Northern Ireland building control is run by the councils under the Building Regulations (Northern Ireland). We submit full plans or a building notice and book the inspections through to completion.

Neighbours and drains

In England and Wales, if the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations. Scotland and Northern Ireland have no Party Wall Act.

Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.

Questions about building regulations for extensions