Sunbury-on-Thames over-garage extensions, designed and built
Our design and build teams take on over-garage extensions in Sunbury-on-Thames, from the first measured survey through planning and building control to the finished room.
- Guide price in Sunbury-on-ThamesFrom £26,500 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsKT12, TW16, TW17
Over-garage extension prices in Sunbury-on-Thames
Prices below are for Sunbury-on-Thames, using the South East England factor of ×1.12. They are guide ranges including VAT for the build only, not a quote.
Typical rates in Sunbury-on-Thames: £2,020 to £3,810 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £26,500 – £33,000 | £28,000 – £36,500 | £36,000 – £46,000 |
| Over a large single garage 16 m² | £32,000 – £39,500 | £37,500 – £48,500 | £48,000 – £61,000 |
| Over a double garage 24 m² | £48,000 – £59,500 | £56,000 – £73,000 | £72,500 – £91,500 |
Try the guide-price tool to see a range for your own size and finish.
Covering Sunbury-on-Thames
Postcode districts we cover around Sunbury-on-Thames include KT12, TW16, TW17. We also work in nearby Walton-on-Thames (1 mile), West Molesey (2 miles), Ashford, Surrey (3 miles), Weybridge (3 miles).
Just over the Greater London border, Hampton is about 2 miles away. In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
Will the council need to approve it?
In England any side extension over one storey, including a room built over a side garage, needs a householder planning application. The fee is £548 from 1 April 2026 and councils aim to decide within 8 weeks.
The planning position for a specific Sunbury-on-Thames address depends on its history and any designations, which is why we check it at the first visit.
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).
Included in a typical project
- New floor structure, walls and roof
- Opening into the existing first floor
- Strengthening or rebuilding the garage walls if needed
- Insulation, electrics, heating and finish
- Design and householder planning application
From first visit to completion
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
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Questions people ask about over-garage extensions
Who do I contract with for an over-garage extension in Sunbury-on-Thames?
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 Sunbury-on-Thames 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.
Do you cover all of Sunbury-on-Thames?
Yes. We cover Sunbury-on-Thames and the surrounding parts of Surrey. Site visits are free and there is no obligation.
How much does a room over a garage cost?
Our guide range is about £2,020 to £3,810 per m² including VAT. A single-garage room of about 12 m² usually costs £28,000 to £36,500 at standard spec, more if the garage needs rebuilding.
Does building over a garage need planning permission?
In England and the rest of the UK, adding a storey over a side garage almost always needs a planning application, because two-storey side extensions are outside permitted development.
Book a free site visit in Sunbury-on-Thames
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.