Two-storey side extensions in Thamesmead

Before you start in Thamesmead, here's what applies.

Postcode districts: SE28
County / area: Greater London, England
Price region: London
Guide price: £103,500–£138,500 (£2,460–£3,300 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Abbey Wood (1.3 miles), Belvedere (1.6 miles), Plumstead (2.1 miles)
First visit: Free, no obligation

About a two-storey side extension

A two-storey side extension is a new two-floor addition built into the space beside your house, often over a driveway or side passage. It typically adds one or two bedrooms upstairs and a utility, study or larger kitchen below, without giving up rear garden.

Around Thamesmead we also work in Abbey Wood, Belvedere and Plumstead, and across the rest of Greater London. Postcode district in and near Thamesmead: SE28.

What it costs in Thamesmead

A guide price for Thamesmead: around £103,500–£138,500 for a 3 m × 7 m footprint on two floors (42 m² of new floor space). That works out at £2,460–£3,300 per m² of new floor space, including VAT at 20%. We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.

Spec	Per m²	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£2,260–£3,040 per m²	£95,000–£127,500
Standard	£2,460–£3,300 per m²	£103,500–£138,500
Premium	£2,950–£3,960 per m²	£124,000–£166,500

Planning and building regulations in Thamesmead

In England, a two-storey side extension always needs householder planning permission, because permitted development only allows single-storey extensions beyond a side wall. The fee is £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Expect them to look at set-back, roof height, gaps to the boundary and the effect on neighbours.

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 Thamesmead homes

Matching the ridge and roof

A hipped house usually needs a hipped extension roof, and a gabled house a gable. Matching the pitch, tiles, ridge detail and brick bond is what makes a side extension look original rather than added, and councils look closely at it on a front-facing addition.

Side windows, boundaries and gutters

Upstairs windows in the side wall face the neighbour, so they are usually obscure-glazed and fixed, or left out. Building close to the boundary also raises questions about foundations, overhanging gutters and access for maintenance, so we design the eaves and gutter to stay within your land.

How we'd run your project

Measure and listen
A visit to Thamesmead to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Plans, then approval
Measured survey, design, then the right approval route for your house. We explain each step before we take it.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
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 two-storey side extensions in Thamesmead

Which postcodes do you cover around Thamesmead?

We cover Thamesmead (SE28) and nearby places including Abbey Wood, Belvedere and Plumstead, plus the rest of Greater London. The first site visit is free.

Do I need planning permission for a two-storey side extension in Thamesmead?

Thamesmead 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.

How much does a two-storey side extension cost in Thamesmead?

Our guide for London, which covers Thamesmead, is £2,460–£3,300 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £103,500–£138,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

How long does a two-storey side extension 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.

Can I build a two-storey side extension over my driveway?

Yes, if the drive is wide enough for a useful room and the council accepts the design. You may lose off-road parking, which some councils weigh up, and the foundations need to suit the ground below. We check parking, drains and meter positions at the free site visit before any drawings are prepared.

Nearby

Close to Thamesmead? We work across the area, including:

Other extensions in Thamesmead

All two-storey extension services in Thamesmead · Two-storey side extensions across Greater London

Book a free site visit in Thamesmead and we'll tell you what's possible, what approvals you need and what the design stage would cost.