Double-storey extensions in Dorset

Covering Dorset

Our coverage across Dorset includes Bournemouth, Poole, Weymouth and Christchurch.

Homes in the South West

The South West mixes stone and render cottages, Victorian terraces in the larger towns and modern estates, and many historic centres are conservation areas where materials and roof shapes are closely controlled.

What goes into a double-storey extension?

A double-storey extension adds new rooms on both the ground and first floor in one build, typically a larger kitchen or living space downstairs and an extra bedroom or bathroom above. Because the roof and foundations are shared, the cost per square metre is usually lower than a single-storey extension.

Householder planning application
Foundations, steelwork, brick and block walls, roof
Windows, insulation, plastering, electrics and plumbing

How much does a double-storey extension cost in Dorset?

Typical ranges for double-storey extensions. Ground conditions, access and specification move the final figure, which we fix in writing before work starts.

Double-storey extensions	Guide price incl. VAT
Standard specification	£2,400 to £2,900 per m²
Good specification	£2,900 to £3,400 per m²
High specification	£3,400 to £3,850 per m²

How is a double-storey extension approved in Dorset?

In England we deal with the council’s planning team for permission or a lawful development certificate, with building control (the council or a registered building control approver) for inspections, and with neighbours under the Party Wall etc. Act 1996 where it applies.

Two-storey rear extensions can sometimes be permitted development in England (no more than 3 m deep, at least 7 m from the rear boundary, roof pitch to match), but most two-storey and all two-storey side extensions need householder planning permission.

What should I think about before starting?

The new roof is tied into the old one, so roof tiles and ridge details need to match.
The first-floor link can mean moving a bathroom or reshaping the landing.

What are the steps?

Tell us about the project. Call, use the guide price tool or send the form with a few photos and a postcode.
Survey at your house. We look at the existing structure, services and access, and agree what the design needs to achieve.
Price and paperwork. The design is priced line by line, and we submit the planning and building control applications.
Build and hand over. Our teams build to the programme, building control inspects, and you get the completion paperwork at the end.

Questions about a double-storey extension in Dorset

Is a two-storey extension better value than a single-storey one?

Per square metre, usually yes, because the foundations and roof serve two floors of space.

How long does a two-storey extension take?

Around 14 to 24 weeks on site, plus the planning period before that.

How do I get a price for double-storey extensions in Dorset?

Use the guide price tool for a ballpark figure, then book a visit for a fixed written price for the agreed specification.

Double-storey extensions near Dorset

Learn more about double-storey extensions, or see every project we cover in Dorset.