Two-storey extensions for semi-detached houses in Dalgety Bay

Dalgety Bay: the key facts for this kind of project.

Postcode districts: KY11
County / area: Fife, 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: Rosyth (3.4 miles), Queensferry (3.6 miles), Burntisland (4.7 miles)
Distance to Dunfermline: about 4.9 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 Dalgety Bay we also work in Rosyth, Queensferry and Burntisland, and across the rest of Fife. Postcode district in and near Dalgety Bay: KY11.

What it costs in Dalgety Bay

Expect a two-storey extension for a semi-detached house in Dalgety Bay to land somewhere around £52,500–£71,000 for a 4 m × 3.5 m footprint on two floors (28 m² of new floor space). Our Scotland guide rate is £1,880–£2,540 per m², including VAT. 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 Dalgety Bay

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 Dalgety Bay homes

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.

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 Dalgety Bay to understand how you live in the house now and what the extra rooms need to do, plus a first look at the structure.
Drawings, then consent
We draw the scheme, check it against the rules in Scotland, and take it through the right consent with the council.
Engineer it
Foundations sized for two floors, steels for any openings, and a building warrant, all before anyone starts on site.
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 extensions for semi-detached houses in Dalgety Bay

Who handles building standards for a project in Dalgety Bay?

We handle it as part of the project. What's needed in Scotland: 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. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

Which postcodes do you cover around Dalgety Bay?

We cover Dalgety Bay (KY11) and nearby places including Rosyth, Queensferry and Burntisland, plus the rest of Fife. The first site visit is free.

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.

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.

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.

Nearby

Other towns near Dalgety Bay:

Other extensions in Dalgety Bay

All two-storey extension services in Dalgety Bay · Two-storey extensions for semi-detached houses across Fife

Send us your postcode and a few details. We'll get back to you to arrange a visit and talk through your options.