Mortlake, Greater London
Two-storey rear extension in Mortlake
Thinking about a two-storey rear extension in Mortlake? A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. Our team handles the drawings, the planning route and the build, and your contract is with one company throughout.
Mortlake and its postcode districts SW13, SW14 and TW9 are part of our Greater London coverage. In Mortlake, a two-storey rear extension is worth comparing with the cost of moving once stamp duty, agents' and legal fees are counted.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a two-storey rear extension cost in Mortlake?
Guide prices for a two-storey rear extension in Mortlake start from our London rate of £2,340–£3,510 per square metre, including VAT. London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.
| Size | Guide price inc VAT |
|---|---|
| 3 m × 5 m footprint, two floors (30 m²) | £70,000–£105,500 |
| 4 m × 6 m footprint, two floors (48 m²) | £112,500–£168,500 |
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 two-storey rear extension in Mortlake?
Whether your two-storey rear extension in Mortlake needs a planning application depends on its size, your house and any local restrictions.
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.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
What are homes in Mortlake like to extend?
Much of Mortlake 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 two-storey rear extension in Mortlake comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
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.
Two-storey rear extensions near Mortlake
From Mortlake, the nearest places we also cover are East Sheen (0.5 miles) and Barnes (0.9 miles).
- Two-storey rear extension in East Sheen
- Two-storey rear extension in Barnes
- Two-storey rear extension in Kew
- Two-storey rear extension in Roehampton
- Two-storey rear extension in Chiswick
Other work in Mortlake:
FAQ
Two-storey rear extension questions in Mortlake
How long does a rear extension take to build in Mortlake?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Do I need planning permission for a rear extension in Mortlake?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Will we need to move out?
Rarely. The first-floor opening is made late in the job and sealed with temporary screens.
Is the site visit in Mortlake free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
How much does a two-storey rear extension cost in Mortlake?
As a guide, £2,340–£3,510 per square metre including VAT for a standard specification. For example, 3 m × 5 m footprint, two floors (30 m²): about £70,000–£105,500 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.