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Walthamstow, Greater London

Semi-detached rear extension in Walthamstow

Single or two-storey extensions for semi-detached houses, with side access and one party wall. We design, get the approvals for and build rear extensions for semi-detached houses in Walthamstow and the surrounding area, with one contract from the first survey to building control sign-off.

Walthamstow and its postcode districts E4, E10, E11 and E17 are part of our Greater London coverage. Where a Walthamstow semi already has a small lean-to at the back, we usually replace it rather than extend it.

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Tell us about the house and we'll call to arrange a free, no-obligation visit.

How much does a semi-detached rear extension cost in Walthamstow?

A semi-detached rear extension in Walthamstow is priced at £2,470–£4,030 per square metre including VAT as a guide, before kitchen fit-out and fees. London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.

Semi-detached rear extension prices in Walthamstow
SizeGuide price inc VAT
3 m wide × 4 m deep (12 m²)£29,500–£48,500
4 m wide × 5 m deep (20 m²)£49,500–£80,500
4 m wide × 6 m deep (24 m²)£59,500–£96,500

Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.

Do you need planning permission for a semi-detached rear extension in Walthamstow?

The planning route for a semi-detached rear extension in Walthamstow is set by England's householder rules and your council.

In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.

A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.

England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.

Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.

What are homes in Walthamstow like to extend?

Much of Walthamstow is Victorian and Edwardian terraced housing with narrow back additions, which suits side returns, wraparounds and 3 metre rear extensions. Many streets are in conservation areas, gardens are short, and almost everything comes through the house or along a rear alley.

How a semi-detached rear extension in Walthamstow comes together

  1. Look round and measure

    A free visit to see the back of the house, measure it, check the drains and boundaries and hear what you need.

  2. Options and costs

    We draw layout options and price each one, so the budget shapes the design rather than surprising you later.

  3. Paperwork handled

    Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.

  4. Build and sign-off

    We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.

Semi-detached rear extensions near Walthamstow

Close by, we work in Highams Park, about 1.3 miles away, and Tottenham Hale, about 1.7 miles away.

Other work in Walthamstow:

All rear extensions in Walthamstow

FAQ

Semi-detached rear extension questions in Walthamstow

How much does a semi-detached rear extension cost in Walthamstow?

As a guide, £2,470–£4,030 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £29,500–£48,500 at that rate. Your written price follows the survey.

Do I need a party wall agreement?

In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.

How long does a semi extension take?

10 to 16 weeks on site for a single-storey extension.

Is the site visit in Walthamstow free?

Yes. We visit, measure up and talk through the options with no cost and no obligation.

What postcode areas do you cover around Walthamstow?

Including E4, E10, E11 and E17, and the surrounding Greater London area.

Will I need a structural engineer?

Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.

Next step

See what your rear extension would cost

Get a guide price online in a couple of minutes, or book a free site visit and we'll measure up and talk you through the planning route.

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