Two-storey extensions for semi-detached houses in Berwick-upon-Tweed

Useful details for planning a two-storey extension for a semi-detached house in Berwick-upon-Tweed.

Postcode districts: TD15
County / area: Northumberland, England
Price region: North East England
Guide price: £50,500–£68,000 (£1,800–£2,430 per m²)
Approval route: Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission.
Nearest towns: Alnwick (27.2 miles), Amble (34.3 miles), Hadston (36.3 miles)
Distance to Blyth: about 48.4 miles
First visit: Free, no obligation

About a two-storey extension for a semi-detached house

A two-storey extension for a semi-detached house is a two-floor addition to the rear, the open side, or both, designed around the attached neighbour on one side. The rear is often the simplest option and can sometimes be permitted development, while a side extension uses the gap on the detached side. Both need care with the shared party wall and the neighbour's light.

Berwick-upon-Tweed sits about 48.4 miles from Blyth. Closer to home, Alnwick is 27.2 miles away and Amble 34.3 miles.

What it costs in Berwick-upon-Tweed

Guide prices for two-storey extensions for semi-detached houses in North East England are around £1,800–£2,430 per m² of new floor space, including VAT. For a typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space), that's roughly £50,500–£68,000. We'll give you a written design-stage price first, then a fixed build price once the drawings are agreed.

Spec	Per m²	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£1,660–£2,240 per m²	£46,500–£62,500
Standard	£1,800–£2,430 per m²	£50,500–£68,000
Premium	£2,160–£2,920 per m²	£60,500–£81,500

Planning and building regulations in Berwick-upon-Tweed

In England, a two-storey rear extension on a semi can be permitted development if it goes no more than 3 m beyond the original rear wall and stays 7 m from the rear boundary, with matching materials and roof pitch. A two-storey side or wraparound extension always needs planning permission, costing £548 (or £575 for applications made from 8 December 2026). Protected areas such as conservation areas exclude two-storey rear permitted development.

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 Berwick-upon-Tweed homes

Rear, side or both

On a semi, a rear extension sits against the attached neighbour, while a side extension faces the detached neighbour and the street. We compare the space, cost and approval route for each, and for a wraparound, before you commit to one design.

The attached neighbour's light

A two-storey rear extension next to the party wall can take light from the neighbour's rear windows. Councils often use a 45-degree test, so the first floor may need to be shorter than the ground floor or set in from the shared boundary.

How we'd run your project

Look at the house
We start in Berwick-upon-Tweed with a free visit: measurements, photos, a look at the loft and drains, and a frank chat about budget.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in England before drawing in detail.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.

Questions about two-storey extensions for semi-detached houses in Berwick-upon-Tweed

How long does a two-storey extension for a semi-detached house 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.

How much does a two-storey extension for a semi-detached house cost in Berwick-upon-Tweed?

Our guide for North East England, which covers Berwick-upon-Tweed, is £1,800–£2,430 per m² including VAT. A typical project with a 4 m × 3.5 m footprint on two floors (28 m² of new floor space) comes to about £50,500–£68,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Do I need planning permission for a two-storey extension for a semi-detached house in Berwick-upon-Tweed?

Berwick-upon-Tweed is in England, so England planning rules apply. Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

What if my neighbour has already extended?

That often helps. An existing extension next door can reduce the effect of yours on their light, and may show what the council accepts on your street. It can also mean building alongside their wall, so we check its position, foundations and any windows facing your plot at the survey.

Should I extend my semi to the side or the rear?

It depends on your plot and what you need. A rear extension keeps the side drive and can sometimes be permitted development, but it affects the attached neighbour. A side extension keeps the rear garden but always needs planning permission in England. We compare both at the free site visit.

Nearby

Close to Berwick-upon-Tweed? We work across the area, including:

Other extensions in Berwick-upon-Tweed

All two-storey extension services in Berwick-upon-Tweed · Two-storey extensions for semi-detached houses across Northumberland

Tell us about your house in Berwick-upon-Tweed and we'll call you back to arrange a free, no-obligation visit.