Two-storey wraparound extensions in Portland

Quick reference for homeowners in Portland.

Postcode districts: DT5
County / area: Dorset, England
Price region: South West England
Guide price: £124,000–£170,000 (£2,210–£3,040 per m²)
Approval route: Planning permission is needed: the side part takes it outside permitted development in England.
Nearest towns: Weymouth (3.3 miles), Dorchester (10.3 miles), Bridport (17.9 miles)
Distance to Bournemouth: about 26.9 miles
First visit: Free, no obligation

About a two-storey wraparound extension

A two-storey wraparound extension is an L-shaped addition that extends both the side and the rear of your house, on two floors. It gives one of the largest gains in floor space of any extension, typically a big open-plan kitchen and living area below and two or more bedrooms or bathrooms above. In England it needs planning permission, because the side part is more than one storey.

Around Portland we also work in Weymouth, Dorchester and Bridport, and across the rest of Dorset. Postcode district in and near Portland: DT5.

What it costs in Portland

Guide prices for two-storey wraparound extensions in South West England are around £2,210–£3,040 per m² of new floor space, including VAT. For a typical project with an L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space), that's roughly £124,000–£170,000. Keep a contingency of around 10% for things nobody can see until the ground is opened up.

Spec	Per m²	An L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space)
Essential	£2,040–£2,800 per m²	£114,000–£156,500
Standard	£2,210–£3,040 per m²	£124,000–£170,000
Premium	£2,660–£3,650 per m²	£149,000–£204,000

Planning and building regulations in Portland

In England, a two-storey wraparound extension needs householder planning permission, because any extension beyond a side wall must be single storey to be permitted development. The application costs £548 (or £575 for applications made from 8 December 2026). Councils weigh the side part against the street scene and the rear part against neighbours' light and outlook, and should decide within 8 weeks of validation.

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 Portland homes

Two roofs that meet

A wraparound needs the side roof and rear roof to join cleanly, often with a valley or hip where they meet. Getting pitches and ridge heights right keeps rainwater moving and avoids a bulky mass at the back corner, which neighbours and planners notice.

The corner post

At the outside corner of the L, there is no existing wall to carry the floor above. Opening the ground floor fully usually means a steel frame or a corner post, and the engineer's design sets how slim it can be. We decide early whether you want a clear corner or a visible post.

How we'd run your project

Look at the house
We start in Portland with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Portland.
Price it properly
Once the engineer's calculations are in, we fix the build price in writing, with a clear list of what's included.
Build it
The new structure goes up first, then we open into the house, finish inside and get the completion certificate.

Questions about two-storey wraparound extensions in Portland

How much does a two-storey wraparound extension cost in Portland?

Our guide for South West England, which covers Portland, is £2,210–£3,040 per m² including VAT. A typical project with an L-shaped footprint of about 28 m² wrapping the side and rear, on two floors (56 m² of new floor space) comes to about £124,000–£170,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Which postcodes do you cover around Portland?

We cover Portland (DT5) and nearby places including Weymouth, Dorchester and Bridport, plus the rest of Dorset. The first site visit is free.

How long does a two-storey wraparound 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.

Is a wraparound extension better than separate side and rear extensions?

Building both at once usually costs less than two separate projects, because you pay for one set-up, one scaffold, one roof junction and one set of approvals. It also lets the layout be designed as a whole. The trade-off is a larger single outlay and a longer build, often 16 to 24 weeks at this size.

Does a wraparound extension need steel?

Almost always. Opening the corner of the house and the old rear wall to make one open-plan space means steel beams, and often a steel post or frame at the outside corner. The structural engineer sizes these, and the steel is ordered once the design is fixed, which is one reason a wraparound needs careful sequencing.

Nearby

We also cover places near Portland, including:

Other extensions in Portland

All two-storey extension services in Portland · Two-storey wraparound extensions across Dorset

Book a free site visit in Portland and we'll tell you what's possible, what approvals you need and what the design stage would cost.