Extensions over a garage in Harrow Weald
Our extensions over a garage service in Harrow Weald covers everything: measured survey, design, planning or permitted development checks, structural design, building control and the build itself.
Before you start in Harrow Weald, here's what applies.
- Postcode districts
- HA7
- County / area
- Greater London, England
- Price region
- London
- Guide price
- £38,000–£55,000 (£2,100–£3,060 per m²)
- Approval route
- Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
- Nearest towns
- Wealdstone (0.7 miles), Hatch End (1.6 miles), Harrow (2.2 miles)
- First visit
- Free, no obligation
About an extension over a garage
An extension over a garage suits you if you have an attached single garage beside the house and need an extra bedroom or a larger main bedroom with an en-suite. You get an inspection of the garage structure, a design that matches the house, the approvals your nation needs, structural design, building regulations approval and the build, carried out by vetted teams working under S&K.
Around Harrow Weald we also work in Wealdstone, Hatch End and Harrow, and across the rest of Greater London. Postcode district in and near Harrow Weald: HA7.
What it costs in Harrow Weald
Expect an extension over a garage in Harrow Weald to land somewhere around £38,000–£55,000 for 3 m × 6 m of new first-floor space (18 m²). Our London guide rate is £2,100–£3,060 per m², including VAT. Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.
| Spec | Per m² | 3 m × 6 m of new first-floor space (18 m²) |
|---|---|---|
| Essential | £1,930–£2,820 per m² | £35,000–£50,500 |
| Standard | £2,100–£3,060 per m² | £38,000–£55,000 |
| Premium | £2,520–£3,670 per m² | £45,500–£66,000 |
Planning and building regulations in Harrow Weald
In England, most garages sit beside the house, so building over one makes a two-storey extension beyond a side wall, which always needs planning permission. If the garage is at the rear, the 3 m and 7 m rules for two-storey rear extensions apply, measured from the original house. A householder application costs £548 (or £575 for applications made from 8 December 2026).
Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.
Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.
Design points for Harrow Weald homes
Garage walls and the door opening
Garage walls are often a single skin of brick or block with piers, and the wide door opening needs a beam over it. Many over-garage extensions need new inner walls or a steel frame to carry the floor and to insulate properly, which we confirm before the design is fixed.
Checking the garage foundations
Garages are often built on shallow strip footings sized for a single-storey wall and a light roof. A trial hole shows their depth and condition, and the engineer decides whether they can carry two storeys or need underpinning or new foundations inside the garage.
How we'd run your project
Start at your house
We come to your home in Harrow Weald, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Get it approved
Once you're happy with the design we submit it to the council for Harrow Weald and deal with any questions from the planning officer.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build and hand over
We manage the build from groundworks to decoration-ready finish and hand over with the completion paperwork.
Questions about extensions over a garage in Harrow Weald
How much does an extension over a garage cost in Harrow Weald?
Our guide for London, which covers Harrow Weald, is £2,100–£3,060 per m² including VAT. A typical project with 3 m × 6 m of new first-floor space (18 m²) comes to about £38,000–£55,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.
Which postcodes do you cover around Harrow Weald?
We cover Harrow Weald (HA7) and nearby places including Wealdstone, Hatch End and Harrow, plus the rest of Greater London. The first site visit is free.
Do I need planning permission for an extension over a garage in Harrow Weald?
Harrow Weald is in England, so England planning rules apply. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.
How do I get into a room over the garage?
Usually through a new opening off the existing landing or a bedroom, so the stairs stay where they are. If the floor levels do not match, a step or two may be needed inside the new room. Where a landing opening is not practical, a new stair from a converted garage is an option.
Do I need to convert the garage as well?
No. You can keep the garage for parking or storage and build only the room above, as long as the floor between them and any door into the house meet fire separation rules. Converting the garage at the same time is often good value, because the walls and foundations may be upgraded anyway.
Nearby
Nearby towns we cover for extensions over a garage:
Other extensions in Harrow Weald
- Rear
- Side
- Wraparound
- Part two-storey
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Harrow Weald · Extensions over a garage across Greater London
Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.