Extensions over a garage in Horley
If you live in Horley and need more room without moving, an extension over a garage is worth a serious look. We handle the drawings, approvals, structure and build.
Before you start in Horley, here's what applies.
- Postcode districts
- RH6
- County / area
- Surrey, England
- Price region
- South East England
- Guide price
- £34,500–£50,500 (£1,930–£2,800 per m²)
- Approval route
- Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
- Nearest towns
- Crawley (4.4 miles), Redhill (4.6 miles), Reigate (4.8 miles)
- Distance to Woking
- about 20 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 postcode district RH6 in and around Horley, along with neighbouring Crawley, Redhill and Reigate.
What it costs in Horley
Expect an extension over a garage in Horley to land somewhere around £34,500–£50,500 for 3 m × 6 m of new first-floor space (18 m²). Our South East England guide rate is £1,930–£2,800 per m², including VAT. Design fees, structural calculations and approval fees are separate and listed on our prices page.
| Spec | Per m² | 3 m × 6 m of new first-floor space (18 m²) |
|---|---|---|
| Essential | £1,770–£2,580 per m² | £32,000–£46,500 |
| Standard | £1,930–£2,800 per m² | £34,500–£50,500 |
| Premium | £2,310–£3,370 per m² | £41,500–£60,500 |
Planning and building regulations in Horley
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 Horley homes
Matching the house
A room over a garage usually sits beside the front of the house in full view, so roof form, ridge height, windows and brick matter. Setting the front wall and ridge back slightly from the main house usually helps it look as if it belongs.
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
Free site visit
We visit your home in Horley, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in England before drawing in detail.
Structure and building control
A structural engineer sizes the foundations and steels, and we get building regulations approval before work starts.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.
Questions about extensions over a garage in Horley
How long does an extension over a garage take?
Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.
How much does an extension over a garage cost in Horley?
Our guide for South East England, which covers Horley, is £1,930–£2,800 per m² including VAT. A typical project with 3 m × 6 m of new first-floor space (18 m²) comes to about £34,500–£50,500. 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 Horley?
We cover Horley (RH6) and nearby places including Crawley, Redhill and Reigate, plus the rest of Surrey. The first site visit is free.
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.
Can my garage take a room on top?
Sometimes, but it needs checking. Many garages are built on shallow footings with thin walls, designed only for a single storey. We dig a trial hole and inspect the walls, and the structural engineer decides whether to reuse them, strengthen them, underpin the footings or build new foundations inside the garage.
Nearby
We also cover places near Horley, including:
Other extensions in Horley
- Rear
- Side
- Wraparound
- Part two-storey
- First floor
- Semi-detached
- Detached
- Kitchen and bedrooms
- Bedroom and en-suite
All two-storey extension services in Horley · Extensions over a garage across Surrey
Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.