Two-storey extensions for semi-detached houses in Edinburgh

Edinburgh: the key facts for this kind of project.

Postcode districts: EH1, EH2, EH3, EH4, EH5, EH6 and nearby districts
County / area: Edinburgh and the Lothians, Scotland
Price region: Scotland
Guide price: £52,500–£71,000 (£1,880–£2,540 per m²)
Approval route: Planning permission is usually needed: Class 1B permitted development only applies if every part of the extension is at least 10 m from all boundaries. A building warrant is needed before work starts.
Nearest towns: Colinton (3.9 miles), Loanhead (5.2 miles), Musselburgh (5.7 miles)
First visit: Free, no obligation

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

This service suits you if you own a semi-detached house and want to add bedrooms and living space without moving. On a semi, the main questions are which side to build on and how to treat the attached neighbour. You get a survey, design options, the approvals your nation needs and the build, carried out by vetted teams working under S&K.

Around Edinburgh we also work in Colinton, Loanhead and Musselburgh, and across the rest of Edinburgh and the Lothians. Postcode districts in and near Edinburgh: EH1, EH2, EH3, EH4, EH5, EH6 and nearby districts.

What it costs in Edinburgh

Guide prices for two-storey extensions for semi-detached houses in Scotland are around £1,880–£2,540 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 £52,500–£71,000. These are guides, not quotes. Ground conditions, steelwork and access can move the figure either way.

Spec	Per m²	A 4 m × 3.5 m footprint on two floors (28 m² of new floor space)
Essential	£1,730–£2,330 per m²	£48,500–£65,500
Standard	£1,880–£2,540 per m²	£52,500–£71,000
Premium	£2,260–£3,050 per m²	£63,000–£85,500

Planning and building standards in Edinburgh

In Scotland, Class 1B permitted development needs a two-storey extension to be at least 10 m from every boundary, which a semi-detached house cannot meet on the attached side. In practice a two-storey extension to a semi needs a householder application, which costs £371 and is decided within two months, followed by a building warrant.

Approval in Scotland: Householder planning application: £371. Councils have two months to decide a local planning application.

Building standards: A building warrant from the council's building standards service before work starts, and a completion certificate at the end. Scotland uses its own Technical Handbooks.

Design points for Edinburgh homes

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.

Keeping the pair balanced

Semis are designed as matching pairs, and a side extension changes that balance. Setting the side extension back from the front wall and keeping its ridge lower helps the pair still read as a pair, which councils' design guides commonly ask for.

How we'd run your project

Free site visit
We visit your home in Edinburgh, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Get it approved
Once you're happy with the design we submit it to the council for Edinburgh and deal with any questions from the planning officer.
Structure and building standards
A structural engineer sizes the foundations and steels, and we get a building warrant before work starts.
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 Edinburgh

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

Edinburgh is in Scotland. Planning permission is usually needed: Class 1B permitted development only applies if every part of the extension is at least 10 m from all boundaries. A building warrant is needed before work starts.

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 have two months to decide a local planning application), 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.

Which postcodes do you cover around Edinburgh?

We cover Edinburgh (EH1, EH2, EH3, EH4, EH5, EH6 and nearby districts) and nearby places including Colinton, Loanhead and Musselburgh, plus the rest of Edinburgh and the Lothians. The first site visit is free.

Will a side extension make my semi look like a terrace?

It can if it fills the whole gap to the boundary at first floor and the neighbour does the same. Many councils ask for a first-floor gap to the side boundary or a set-back for this reason. We design the extension to keep the semi reading as one of a pair.

Does a two-storey extension add value to a semi-detached house?

It usually adds value, but the gain is never certain. Nationwide's 2025 research found that 10% more floor area was linked to about 5% higher value, and that adding a double bedroom and bathroom to a three-bed, one-bathroom house could add up to 24%. Every street has a ceiling price, so check local sales first.

Nearby

Nearby towns we cover for two-storey extensions for semi-detached houses:

Other extensions in Edinburgh

All two-storey extension services in Edinburgh · Two-storey extensions for semi-detached houses across Edinburgh and the Lothians

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