Two-storey extensions in Greater London

Greater London at a glance

Nation: England
Price region: London
Postcode areas: BR, CR, DA, E, EC, EN, HA, IG, KT, N, NW, RM, SE, SM, SW, TN, TW, UB, W, WC
Towns listed: 215
Site visits: Free, no obligation

Choose your town

Guide prices in London

Extension type	Per m²	Typical project
Two-storey rear extension	£2,400–£3,240 per m²	£67,000–£90,500
Two-storey side extension	£2,460–£3,300 per m²	£103,500–£138,500
Two-storey wraparound extension	£2,580–£3,540 per m²	£144,500–£198,000
Part single, part two-storey	£2,400–£3,300 per m²	£86,500–£119,000
Extension over a garage	£2,100–£3,060 per m²	£38,000–£55,000
First-floor extension over an existing single storey	£2,160–£3,120 per m²	£30,000–£43,500
Two-storey front extension	£2,640–£3,600 per m²	£31,500–£43,000

Including VAT, Standard spec. See all prices and fees.

Across Greater London we cover Brent (HA0), Islington (EC1V), Westminster (SW1), Bexley (DA5), Barking (E6), Archway (N6), Sutton (SM2) and Croydon (CR0), plus the smaller places around them.

Which type suits your house?

If you're not sure which type fits, that's what the free visit is for. We'll sketch the realistic options for your house in Greater London, with a rough idea of the approval route and cost for each.

The rules in England

Greater London is in England. Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission. 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.

The full England rules explained

Extension types

By house type

Rooms and uses

Design and approvals

Questions about extensions in Greater London

How much does a two-storey extension cost in Greater London?

In London our guide for a two-storey rear extension is £2,400–£3,240 per m² including VAT, about £67,000–£90,500 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Side and wraparound extensions cost a little more per m².

Do I need planning permission in Greater London?

Two-storey rear: up to 3 m deep and 7 m from the rear boundary under permitted development. Side, wraparound and front: planning permission. 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).

Do you cover the whole of Greater London?

Yes. We list the main towns here, but we cover the whole of Greater London including villages. The first site visit is free.

What happens at the first visit?

We look at your house, the boundaries, access and drains, talk through what you need and explain the approvals. Then we price the design stage, including the measured survey, in writing.