Building regulations for extensions across Thornbury
Need building regulations for extensions in Thornbury? We survey the house, prepare what the council needs and deal with the officers until a decision is made.
- Guide price in ThornburyFrom £900 inc VAT
- Approval routeFull plans or building notice
- Timescale2–5 weeks for drawings
- Postcode districtsBS35
Who this service is for
- Homeowners using their own builder who need the drawings
- Glass-heavy designs that need energy calculations
- Every extension, whatever the planning route
What it costs in Thornbury
Fees below are our Thornbury guide (×1.02, the South West England factor), including VAT. Council and building control fees are extra.
| 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.
Want a range for your exact size? The guide-price tool takes about a minute.
Local to Thornbury
Site visits are available across Thornbury (BS35). Neighbouring towns we cover include Yate (7 miles), Mangotsfield (8 miles), Kingswood (10 miles), Dursley (10 miles).
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.
Do I need planning permission in Thornbury?
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).
How the project works
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
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Questions answered
Will my neighbours in Thornbury be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
Do you cover all of Thornbury?
Yes. We cover Thornbury and the surrounding parts of Gloucestershire. Site visits are free and there is no obligation.
How long does this take for a Thornbury home?
2–5 weeks for drawings, depending on the council and the complexity of the project.
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.
What are the insulation standards for an extension?
In England, new walls in an extension should achieve a U-value of 0.18 W/m²K, roofs 0.15 and floors 0.18, with windows at 1.4 and rooflights at 2.2. Wales, Scotland and Northern Ireland set their own figures.
Book a free site visit in Thornbury
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.