Building regulations for extensions in Cornwall
We prepare building regulations for extensions for homes across Cornwall, on their own or as the first stage of a full design and build project.
- Guide priceFrom £900 inc VAT
- Approval routeFull plans or building notice
- Towns covered9
- Site visitFree, no obligation
Included in a typical project
- Completion certificate on sign-off
- Energy and glazing checks, including whole-house calculations if needed
- Inspection bookings throughout the build
- Submission to the council or a registered building control approver
- Structural calculations for beams, lintels and foundations
- Building regulations drawings and written specification
Covering Cornwall
Towns we cover in Cornwall include Redruth, Falmouth, St Austell, Truro, Camborne, Newquay, Penzance, Bodmin. In the South West, local stone, render and brick vary from town to town, so matching materials is a big part of designing an extension that looks right.
Design and approval fees for Cornwall
Guide fees for Cornwall including VAT, using our South West England factor of ×1.02. Council and building control charges are not included.
| Option | What it covers | Guide price |
|---|---|---|
| Essential | Building regulations drawings for a simple single-storey extension | £900 – £1,850 |
| Standard | Drawings plus structural calculations | £1,300 – £2,700 |
| Premium | Complex or two-storey pack with energy calculations | £2,200 – £3,900 |
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.
For a figure based on your own dimensions, use our guide-price tool.
Will the council need to approve it?
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.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
From first visit to completion
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
We visit your Cornwall home, measure up, talk through what you want and check the planning position.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Common questions in Cornwall
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Cornwall, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do I need building regulations approval in Cornwall?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Do you cover all of Cornwall?
Yes, across the whole of Cornwall. Site visits are free and there is no obligation.
Full plans or building notice?
A full plans application gets the drawings checked before work starts, which we usually recommend for extensions. A building notice is quicker to submit but carries more risk if something needs changing on site.
Who are building control?
Either your local council’s building control team or a registered building control approver. Both inspect the work and issue the completion certificate.
Book a free site visit in Cornwall
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.