Two-storey side extensions in Blandford Forum

Before you start in Blandford Forum, here's what applies.

Postcode districts: DT11 and SP7
County / area: Dorset, England
Price region: South West England
Guide price: £88,500–£119,000 (£2,110–£2,830 per m²)
Approval route: Planning permission is needed: in England, permitted development only allows single-storey extensions to the side.
Nearest towns: Wimborne Minster (9.4 miles), Broadstone (10.2 miles), Canford Heath (11.3 miles)
Distance to Bournemouth: about 15.7 miles
First visit: Free, no obligation

About a two-storey side extension

A two-storey side extension suits a detached or semi-detached house with a side garden, driveway or garage wide enough to build on. You get a design that sits comfortably on the street, a planning application or permitted development check depending on your nation, structural design, building regulations approval and the build itself. We manage the whole process, and the work is carried out by vetted teams working under S&K.

We cover Blandford Forum (DT11 and SP7) and the places around it, including Wimborne Minster (9.4 miles), Broadstone (10.2 miles) and Canford Heath.

What it costs in Blandford Forum

In South West England, which includes Blandford Forum, we'd expect a two-storey side extension to cost around £88,500–£119,000 for a 3 m × 7 m footprint on two floors (42 m² of new floor space), or £2,110–£2,830 per m² including VAT. Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£1,940–£2,610 per m²	£81,500–£109,500
Standard	£2,110–£2,830 per m²	£88,500–£119,000
Premium	£2,530–£3,400 per m²	£106,500–£143,000

Planning and building regulations in Blandford Forum

In England, a two-storey side extension always needs householder planning permission, because permitted development only allows single-storey extensions beyond a side wall. The fee is £548 (or £575 for applications made from 8 December 2026), and councils should decide within 8 weeks of validation. Expect them to look at set-back, roof height, gaps to the boundary and the effect on neighbours.

Approval in England: 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.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Blandford Forum homes

Set-down and set-back

Councils usually want a two-storey side extension to look subordinate to the house. Setting the front wall back from the main front and dropping the ridge slightly below the main roof helps it read as an addition, and is often expected in local design guidance.

Access and services

Side extensions often cover the only route to the back garden, a gas meter, soil pipes or a drain run. We plan bin and bike access, move meters and pipes where needed and check drains early, because these items affect both cost and layout.

How we'd run your project

Visit and first ideas
One of our team visits your house in Blandford Forum, checks the walls, roof and drains, and sketches out options with you.
Get it approved
Once you're happy with the design we submit it to the council for Blandford Forum and deal with any questions from the planning officer.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build and sign-off
Vetted teams working under S&K build the extension, and we arrange the building control completion certificate at the end.

Questions about two-storey side extensions in Blandford Forum

Do I need planning permission for a two-storey side extension in Blandford Forum?

Blandford Forum is in England, so England planning rules apply. Planning permission is needed: in England, permitted development only allows single-storey extensions to the side. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

Which postcodes do you cover around Blandford Forum?

We cover Blandford Forum (DT11 and SP7) and nearby places including Wimborne Minster, Broadstone and Canford Heath, plus the rest of Dorset. The first site visit is free.

How much does a two-storey side extension cost in Blandford Forum?

Our guide for South West England, which covers Blandford Forum, is £2,110–£2,830 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £88,500–£119,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

How long does a two-storey side extension take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Can I build a two-storey side extension over my driveway?

Yes, if the drive is wide enough for a useful room and the council accepts the design. You may lose off-road parking, which some councils weigh up, and the foundations need to suit the ground below. We check parking, drains and meter positions at the free site visit before any drawings are prepared.

Nearby

Close to Blandford Forum? We work across the area, including:

Other extensions in Blandford Forum

All two-storey extension services in Blandford Forum · Two-storey side extensions across Dorset

Want a figure first? Try our guide price tool, then book a free visit to firm it up.