Thamesmead side return extensions, designed and built
A side return extension in Thamesmead starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide price in ThamesmeadFrom £23,000 inc VAT
- PlanningOften permitted development; party wall notice usual
- Build time10–14 weeks on site
- Postcode districtsDA17, DA18, IG11, SE2, SE18
How much does a side return extension cost in Thamesmead?
For Thamesmead we adjust our national guide rates by ×1.3, the factor we use for London. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Thamesmead: £2,730 to £4,940 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 1.8 m × 4.5 m 8 m² | £23,000 – £28,000 | £24,500 – £31,500 | £31,000 – £40,000 |
| 2 m × 5.5 m 11 m² | £30,000 – £36,000 | £34,000 – £43,000 | £42,500 – £54,500 |
| 2.2 m × 7 m 15 m² | £40,500 – £49,000 | £46,500 – £58,500 | £58,500 – £74,500 |
For a figure based on your own dimensions, use our guide-price tool.
Extensions in and around Thamesmead
Site visits are available across Thamesmead (DA17, DA18, IG11, SE2, SE18, SE28). We also work in nearby Abbey Wood (1 mile), Plumstead (2 miles), Barking (3 miles), Welling (3 miles).
For homes towards Kent, Dartford is around 6 miles away. Across London, terraced houses with narrow side returns and tight access are the norm, which shapes everything from party wall notices to how materials reach the back garden.
Will the council need to approve it?
In England a single-storey side return infill is often permitted development if it stays within the height limits and is no wider than half the width of the original house. Conservation areas, listed buildings and flats always need an application, and the boundary wall usually brings in the Party Wall Act.
Before any drawing is finalised we check whether the house is listed, in a conservation area or subject to an Article 4 direction.
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 boundary wall or raised party wall
- Party wall notice support (England and Wales)
- Design to keep daylight in the middle of the house
- Survey of the outrigger, boundary wall and drainage
- Removal of the side wall and new steelwork
- Kitchen-ready shell or full finish
Light is the design problem. A side return can make the middle of the house darker if the roof is solid, so we model the daylight and usually recommend a glazed slope or a run of rooflights along the boundary edge.
How the project works
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
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Questions people ask about side return extensions
How long does a side return extension take to build in Thamesmead?
On site, typically 10 to 14 weeks once approvals are in place. Before that, allow 6–12 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Thamesmead, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Do you cover all of Thamesmead?
Yes. We cover Thamesmead and the surrounding parts of Greater London. Site visits are free and there is no obligation.
How much does a side return extension cost?
Our guide range is about £2,730 to £4,940 per m² including VAT, so a typical 2 m × 5.5 m infill lands around £34,000 to £43,000 at standard spec in Thamesmead, more in London.
Will the kitchen be darker?
Not if the roof is designed well. A glazed roof or a line of rooflights along the boundary usually makes the room brighter than before.
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.