Extensions over a garage in Brockley
We cover Brockley and the rest of Greater London for extensions over a garage. Start with a free site visit and a plain-English view of what your house and plot can take.
The basics for Brockley at a glance.
- Postcode districts
- SE4
- 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
- New Cross (0.8 miles), Crofton Park (0.8 miles), Ladywell (0.9 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.
We cover Brockley (SE4) and the places around it, including New Cross (0.8 miles), Crofton Park (0.8 miles) and Ladywell.
What it costs in Brockley
Most of the cost of an extension over a garage is set by its size and specification. For Brockley and the rest of London, our guide is £2,100–£3,060 per m² including VAT, so about £38,000–£55,000 for 3 m × 6 m of new first-floor space (18 m²). We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.
| 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 Brockley
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 Brockley homes
Floor levels and headroom
Garage floors are often lower than the house, and the new first floor may not line up with the existing landing. We set the floor level to avoid awkward steps upstairs, while keeping enough headroom in the garage below for a car or storage.
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.
How we'd run your project
Understand the brief
At your home in Brockley we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Brockley.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.
Questions about extensions over a garage in Brockley
Who handles building regulations for a project in Brockley?
We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.
Do I need planning permission for an extension over a garage in Brockley?
Brockley 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.
Which postcodes do you cover around Brockley?
We cover Brockley (SE4) and nearby places including New Cross, Crofton Park and Ladywell, plus the rest of Greater London. The first site visit is free.
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.
Can I add an en-suite above the garage?
Yes, and it is a common choice for a main bedroom. The en-suite needs an extract fan under Part F, a route for the soil pipe down to the drains and enough fall for the waste, which can be harder over a garage. We plan the pipe route through the garage or an outside wall early.
Nearby
Close to Brockley? We work across the area, including:
Other extensions in Brockley
- Rear
- Side
- Wraparound
- Part two-storey
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Brockley · Extensions over a garage across Greater London
Book a free site visit in Brockley and we'll tell you what's possible, what approvals you need and what the design stage would cost.