Two-storey extensions for detached houses in Perth

Perth: the key facts for this kind of project.

Postcode districts: PH1 and PH2
County / area: Perth and Kinross, Scotland
Price region: Scotland
Guide price: £81,000–£108,500 (£1,930–£2,580 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: Scone (2 miles), Bridge of Earn (3.4 miles), Auchterarder (12.6 miles)
First visit: Free, no obligation

About a two-storey extension for a detached house

A two-storey extension for a detached house is a two-floor addition to the side, rear or both of a house that stands on its own plot. Detached houses often have room on more than one side, so there is more choice of layout and fewer shared-wall issues. The design still needs to respect boundaries, neighbours' windows and the look of the house.

Around Perth we also work in Scone, Bridge of Earn and Auchterarder, and across the rest of Perth and Kinross. Postcode districts in and near Perth: PH1 and PH2.

What it costs in Perth

In Scotland, which includes Perth, we'd expect a two-storey extension for a detached house to cost around £81,000–£108,500 for a 3 m × 7 m footprint on two floors (42 m² of new floor space), or £1,930–£2,580 per m² including VAT. Professional fees for drawings and the structural engineer are listed separately on our prices page.

Spec	Per m²	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£1,770–£2,380 per m²	£74,500–£100,000
Standard	£1,930–£2,580 per m²	£81,000–£108,500
Premium	£2,310–£3,100 per m²	£97,000–£130,500

Planning and building standards in Perth

In Scotland, a detached house on a large plot may be able to use Class 1B permitted development if no part of the two-storey extension is within 10 m of any boundary, it is no higher than the house and is not in a conservation area. Otherwise a householder application costs £371. A building warrant is needed either way.

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 Perth homes

Choosing the best side

On a detached house you can often extend on either side or the rear. We look at orientation for daylight, where the stairs and landing are, the distance to each boundary, drains and trees, so the extension goes where it adds the most useful space.

Larger spans and steelwork

Bigger extensions often mean wider openings and longer spans, which need more steel and sometimes a steel frame. The engineer designs these early, because the size of the steel affects ceiling heights, floor depths and the cost.

How we'd run your project

Free site visit
We visit your home in Perth, look at the structure, access and boundaries, and talk through what you want the new rooms to do.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in Scotland before drawing in detail.
Fixed price in writing
With approved drawings and calculations, we give you a fixed build price and a programme you can plan around.
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 detached houses in Perth

Which postcodes do you cover around Perth?

We cover Perth (PH1 and PH2) and nearby places including Scone, Bridge of Earn and Auchterarder, plus the rest of Perth and Kinross. The first site visit is free.

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

Perth 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 much does a two-storey extension for a detached house cost in Perth?

Our guide for Scotland, which covers Perth, is £1,930–£2,580 per m² including VAT. A typical project with a 3 m × 7 m footprint on two floors (42 m² of new floor space) comes to about £81,000–£108,500. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Is a detached house extension a better investment than moving?

It often costs less than the gap between your house and a larger one nearby, once property tax, legal fees and removal costs are counted, but that depends on your area. Extending also has limits: every street has a ceiling price. We give you build costs so you can compare them with local asking prices.

Can I extend a detached house on both sides?

Sometimes. With planning permission, a council may accept extensions on both sides if the house stays well proportioned and keeps gaps to the boundaries. It is more common to extend on one side and the rear, or with a wraparound. We look at the plot as a whole before suggesting more than one extension.

Nearby

The same service in neighbouring towns:

Other extensions in Perth

All two-storey extension services in Perth · Two-storey extensions for detached houses across Perth and Kinross

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