Extensions over a garage in Thamesmead
We design and build over-garage extensions for houses in Thamesmead, with a written price once the survey and design are done and one point of contact throughout.
- Guide price in ThamesmeadFrom £31,000 inc VAT
- PlanningHouseholder application needed
- Build time12–18 weeks on site
- Postcode districtsDA17, DA18, IG11, SE2, SE18
Extensions in and around Thamesmead
Postcode districts we cover around Thamesmead include DA17, DA18, IG11, SE2, SE18, SE28. We also work in nearby Abbey Wood (1 mile), Plumstead (2 miles), Barking (3 miles), Welling (3 miles).
In London, space is at a premium and gardens are often short, so side returns, wraparounds and carefully planned rear extensions tend to make the most of every metre.
Planning rules that apply in Thamesmead
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 Thamesmead 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).
When an over-garage extension makes sense
- Detached and link-detached houses with an attached garage
- Families needing a bedroom without losing garden
- Homes where the landing can connect to the new room
Fitting the new room to the existing landing is the planning puzzle inside the house. We design the connection first, then the roof, so the extension does not end up with awkward steps or a corridor through a bedroom.
Guide prices for Thamesmead
These guide figures apply our London adjustment (×1.3) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Thamesmead: £2,340 to £4,420 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Over a single garage 12 m² | £31,000 – £38,500 | £32,500 – £42,500 | £42,000 – £53,500 |
| Over a large single garage 16 m² | £37,000 – £46,000 | £43,500 – £56,500 | £56,000 – £71,000 |
| Over a double garage 24 m² | £56,000 – £69,000 | £65,500 – £84,500 | £84,000 – £106,500 |
Want a range for your exact size? The guide-price tool takes about a minute.
Our process, step by step
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 Thamesmead home, measure up, talk through what you want and check the planning position.
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
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Over-garage extension questions answered
Who do I contract with for an over-garage extension in Thamesmead?
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.
How long does an over-garage extension take to build in Thamesmead?
On site, typically 12 to 18 weeks once approvals are in place. Before that, allow 8–14 weeks design and approvals.
Do I need building regulations approval in Thamesmead?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Can my garage take the weight of a room on top?
Some can and some cannot. Many garages have a single-skin wall or shallow foundations. Our structural engineer checks this before we give a fixed price.
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 Thamesmead
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.