Two-storey extensions for semi-detached houses in Washwood Heath

What we'd confirm first for a project in Washwood Heath.

Postcode districts: B8, B9, B23 and B24
County / area: West Midlands, England
Price region: West Midlands
Guide price: £56,000–£75,500 (£2,000–£2,700 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: Castle Vale (1.8 miles), Aston (2.4 miles), Birmingham (3.4 miles)
Distance to Birmingham: about 3.4 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.

We cover postcode districts B8, B9, B23 and B24 in and around Washwood Heath, along with neighbouring Castle Vale, Aston and Birmingham.

What it costs in Washwood Heath

Guide prices for two-storey extensions for semi-detached houses in the West Midlands are around £2,000–£2,700 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 £56,000–£75,500. 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	£1,840–£2,480 per m²	£51,500–£69,500
Standard	£2,000–£2,700 per m²	£56,000–£75,500
Premium	£2,400–£3,240 per m²	£67,000–£90,500

Planning and building regulations in Washwood Heath

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 Washwood Heath 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

Measure and listen
A visit to Washwood Heath to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Get it approved
Once you're happy with the design we submit it to the council for Washwood Heath and deal with any questions from the planning officer.
Detail and price
Construction drawings, engineer's calculations and building control sign-off, then a written fixed price for the build.
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 Washwood Heath

Which postcodes do you cover around Washwood Heath?

We cover Washwood Heath (B8, B9, B23 and B24) and nearby places including Castle Vale, Aston and Birmingham, plus the rest of the West Midlands. The first site visit is free.

How much does a two-storey extension for a semi-detached house cost in Washwood Heath?

Our guide for the West Midlands, which covers Washwood Heath, is £2,000–£2,700 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 £56,000–£75,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Who handles building regulations for a project in Washwood Heath?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

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 Washwood Heath? We work across the area, including:

Other extensions in Washwood Heath

All two-storey extension services in Washwood Heath · Two-storey extensions for semi-detached houses across the West Midlands

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