Nailsea double-storey extensions, designed and built
We design and build double-storey extensions for houses in Nailsea, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in NailseaFrom £38,500 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsBS48
Planning and approvals in Nailsea
In England a two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
The planning position for a specific Nailsea address depends on its history and any designations, which is why we check it at the first visit.
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).
Covering Nailsea
Across BS48, we can visit, measure and advise. Neighbouring towns we cover include Portishead (3 miles), Clevedon (4 miles), Weston-super-Mare (11 miles), Keynsham (11 miles).
Kingswood, in Gloucestershire, is roughly 11 miles from Nailsea and also on our list. 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.
Guide prices for Nailsea
These guide figures apply our South West England adjustment (×1.02) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Nailsea: £1,580 to £3,060 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £38,500 – £46,500 | £44,000 – £58,000 | £56,000 – £73,500 |
| 4 m × 4 m, two floors 32 m² | £50,500 – £60,500 | £58,500 – £77,000 | £75,000 – £98,000 |
| 4 m × 6 m, two floors 48 m² | £75,500 – £91,000 | £88,000 – £115,500 | £112,500 – £147,000 |
Want a range for your exact size? The guide-price tool takes about a minute.
What we take care of
- Insulation, plastering, electrics and plumbing to finish
- Foundations sized for two floors
- Measured survey, design and planning drawings
- Ground and first floor structure, roof tied into the existing roof
- Breaking through at both levels, stairs and landing changes where needed
- Building regulations drawings and structural design
The roof is what makes a two-storey extension look right or wrong. We match the pitch and materials of the main house wherever possible and plan the upstairs layout around the existing landing so the new rooms feel original rather than bolted on.
Our process, step by step
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
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Your questions about a double-storey extension in Nailsea
Do I need building regulations approval in Nailsea?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Who do I contract with for a double-storey extension in Nailsea?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Will my neighbours in Nailsea 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.
Does a double-storey extension need planning permission?
Often, yes. In England a two-storey rear extension can be permitted development only if it projects no more than 3 m and sits at least 7 m from the rear boundary, with matching roof pitch and obscure side windows. Side extensions over one storey always need planning permission. We confirm the route at the survey.
Do I need a Party Wall Agreement?
If you are in England or Wales and the work involves a shared wall or digging foundations close to a neighbour, the Party Wall etc. Act 1996 applies and notices must be served before work starts. We tell you which notices are needed.
Book a free site visit in Nailsea
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.