Double-storey extensions for homes in Wealdstone
Wealdstone homeowners can use us for the whole double-storey extension project: survey, design, planning or permitted development checks, building regulations and the build itself.
- Guide price in WealdstoneFrom £49,000 inc VAT
- PlanningUsually a householder application
- Build time16–24 weeks on site
- Postcode districtsHA1, HA3, HA7
Working in Wealdstone
Our survey diary covers Wealdstone, including HA1, HA3, HA7. Nearby, we also take on projects in Harrow (1 mile), Pinner (2 miles), Wembley (4 miles), Northolt (4 miles).
Bushey, in Hertfordshire, is roughly 3 miles from Wealdstone and also on our list. Across London, terraced houses with narrow side returns and tight access are the norm, which shapes everything from party wall notices to how materials reach the back garden.
Planning rules that apply in Wealdstone
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.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
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.
Applications are decided by the local planning authority (your district, borough or unitary council).
What should I budget for a double-storey extension in Wealdstone?
Labour and material costs vary across the UK, so for Wealdstone we use our London factor (×1.3). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Wealdstone: £2,020 to £3,900 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m, two floors 24 m² | £49,000 – £59,000 | £56,000 – £73,500 | £71,500 – £94,000 |
| 4 m × 4 m, two floors 32 m² | £64,000 – £77,000 | £74,500 – £98,000 | £95,500 – £125,000 |
| 4 m × 6 m, two floors 48 m² | £96,500 – £115,500 | £112,000 – £147,000 | £143,500 – £187,500 |
Try the guide-price tool to see a range for your own size and finish.
When a double-storey extension makes sense
- Growing families who need a bedroom as well as a bigger kitchen
- Homeowners who would otherwise consider moving
- Houses with enough distance to the rear or side boundary
What happens next
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 Wealdstone home, measure up, talk through what you want and check the planning position.
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.
Double-storey extension questions answered
Who do I contract with for a double-storey extension in Wealdstone?
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.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Wealdstone, 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 you cover all of Wealdstone?
Yes. We cover Wealdstone and the surrounding parts of Greater London. Site visits are free and there is no obligation.
Is a two-storey extension cheaper per square metre?
Usually. Our guide range is about £2,020 to £3,900 per m² of new floor area including VAT, compared with £2,280 to £4,420 per m² for single-storey work, because the foundations and roof are shared across two floors.
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.
Book a free site visit in Wealdstone
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.