What is a double-storey extension?
A double-storey extension (also called a two-storey extension) adds rooms on both the ground and first floor in one build. It typically gives a larger kitchen or living space downstairs and an extra bedroom or bathroom above.
How much does a double-storey extension cost in Sutton?
In Sutton, a double-storey extension typically costs £2,150–£3,250 per m² of floor area (both floors), including VAT at 20% (standard rate). For a typical 36 m² project that is roughly £77,500–£117,000. Prices across London are typically 30% above the UK average for this kind of work, which is reflected in the range for Sutton. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (25 m²) | £54,000–£81,000 |
| Typical project (36 m²) | £77,500–£117,000 |
| Larger project (50 m²) | £107,500–£162,500 |
| Rate per m² | £2,150–£3,250 |
The main things that change the cost:
- Total floor area across both floors
- Roof design and how it joins the existing roof
- Brick matching and external finishes
- Bathrooms or en-suites on the first floor
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a double-storey extension in Sutton?
Approvals for a double-storey extension in Sutton follow the rules for England. In England an extension of more than one storey can only be permitted development at the rear, no more than 3 metres deep and at least 7 metres from the rear boundary, with matching materials and any upper side windows obscure-glazed. Most double-storey extensions therefore go through a householder planning application.
Where work involves a shared wall, building on the boundary, or digging foundations within 3 metres of a neighbour’s building and deeper than its foundations (or within 6 metres for deeper work), the Party Wall etc. Act 1996 applies and notices must be served before work starts.
If the answer is not clear-cut, we can apply for formal confirmation before you commit to the build.
What we handle
From survey to sign-off, the job normally involves:
- Opening up at both levels with steel beams
- Structural engineer’s calculations
- Building control sign-off
- Electrics, heating, plumbing and plastering
- Foundations, drainage and scaffolding
- Windows, doors and staircase alterations
How long does it take?
The build itself usually takes 14 to 20 weeks on site, after planning and building control approval. Design and approvals come first and typically take 3 to 4 months, depending on the approval route.
Building in Sutton
Space is at a premium in London, so homeowners often build out into the side return or up into the roof rather than move.
We work across Sutton and neighbouring areas such as Carshalton, Wallington and Morden. Postcodes we cover in Sutton include CR44, SM1 and SM2.
How it works
- 01
Free visit
We look at the property, talk through what you want and measure up. There is no charge and no obligation.
- 02
Design and pricing
Design options, then a fixed quote based on the chosen drawings and specification.
- 03
Approvals in place
We handle planning, building control and neighbour notices before work starts.
- 04
Construction and completion
We build, put right any snags and hand over the building control certificate.
Questions about double-storey extensions in Sutton
Can I live at home during the work?
Most families stay put. The shell is built first and the house is opened up late in the job, so disruption inside is limited to a few weeks.
How long does a double-storey extension take in Sutton?
Typically 14 to 20 weeks on site, after planning and building control approval. Design and approvals beforehand usually take 3 to 4 months.
How much does a double-storey extension cost in Sutton?
In Sutton, a double-storey extension typically costs £2,150–£3,250 per m² of floor area (both floors), including VAT at 20% (standard rate). A typical 36 m² project comes to roughly £77,500–£117,000. Your fixed price depends on the survey and drawings.
Does a double-storey extension need planning permission?
Usually. In England a two-storey rear extension can only be permitted development if it is no more than 3 metres deep and at least 7 metres from the rear boundary, and side extensions over one storey always need permission. In practice most are approved through a planning application.
How close can it be to my neighbour?
Councils look at loss of light and outlook for neighbours. Many apply a 45-degree guideline from the nearest neighbouring window. We design to the council’s published guidance to give the application the best chance.