Thornbury, Bristol and South Gloucestershire
Rear extension planning drawings in Thornbury
Measured survey, design options, planning drawings and the application, handled for you. If you live in Thornbury and want to know what a rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Thornbury and its postcode districts BS35 are part of our Bristol and South Gloucestershire coverage. Rear extension applications in Bristol and South Gloucestershire are householder applications, which councils aim to decide within about eight weeks.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
What do rear extension planning drawings cost in Thornbury?
As a guide, £1,000–£2,500 including VAT for a single-storey rear extension, or £2,000–£3,500 for a two-storey scheme. A householder planning application in England costs £548 (£575 for applications made from 8 December 2026), and a lawful development certificate for proposed work costs half the householder fee. Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a rear extension in Thornbury?
Whether your rear extension in Thornbury needs a planning application depends on its size, your house and any local restrictions.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
Councils aim to decide householder applications within 8 weeks of validation, and prior approval within 42 days.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Thornbury like to extend?
Thornbury has Victorian terraces nearer the centre and post-war semis on the edges. Sloping gardens are frequent, which affects floor levels and steps down to the patio.
How a rear extension in Thornbury comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Rear extension planning drawings near Thornbury
Neighbouring places we cover include Stoke Gifford (6.4 miles) and Yate (6.4 miles).
- Rear extension planning drawings in Stoke Gifford
- Rear extension planning drawings in Yate
- Rear extension planning drawings in Chepstow
- Rear extension planning drawings in Mangotsfield
- Rear extension planning drawings in Dursley
Other work in Thornbury:
FAQ
Rear extension planning drawings questions in Thornbury
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.
What postcode areas do you cover around Thornbury?
Including BS35, and the surrounding Bristol and South Gloucestershire area.
Can planning conditions affect the build?
Yes, for example matching materials or obscure glazing. We plan for them.
What do rear extension planning drawings cost in Thornbury?
As a guide, £1,000–£2,500 including VAT for a single-storey rear extension and £2,000–£3,500 for a two-storey scheme, covering the measured survey, design options and the application. The council fee is extra.
Is the site visit in Thornbury free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
Do I need planning permission for a rear extension in Thornbury?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.