Part single, part two-storey extensions in Perth and Kinross

Perth and Kinross at a glance

Nation: Scotland
Price region: Scotland
Postcode areas: KY, PH
Towns covered: 8 listed below, plus surrounding villages
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.
Site visits: Free, no obligation

What a part single, part two-storey extension involves

A part single, part two-storey extension is an extension where the ground floor is wider or deeper than the floor above, so only part of it rises to two storeys. It usually gives a large kitchen or living area with roof lights below and one bedroom or bathroom above. It is often a good way to add space while limiting the effect on neighbours.

Across Perth and Kinross we cover Perth (PH1), Blairgowrie and Rattray (PH10), Crieff (PH5), Auchterarder (PH3), Scone (PH2) and Kinross (KY13), plus the smaller places around them.

Guide price in Scotland

A guide price for Perth and Kinross: around £67,500–£93,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). That works out at £1,880–£2,580 per m² of new floor space, including VAT at 20%. Steelwork for wide openings is the item most likely to move the figure; we'll know once the engineer has designed it.

Spec	Per m²	Typical project
Essential	£1,730–£2,380 per m²	£62,500–£85,500
Standard	£1,880–£2,580 per m²	£67,500–£93,000
Premium	£2,260–£3,100 per m²	£81,000–£111,500

Rules in Scotland

In Scotland, because part of the extension is more than one storey, it is assessed under Class 1B, which needs at least 10 m to every boundary for permitted development. On most plots that is not possible, so the extension needs a householder application (£371, decided within two months). A building warrant is also needed before any work starts.

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.

There is no Party Wall Act in Scotland. Shared walls and boundaries are governed by title deeds and common law, so we speak to neighbours early and record the condition of shared structures.

Getting the design right

Structure at the step

The first-floor wall above often sits over the new open-plan space, so it needs a steel beam or frame to carry it. Loads come down at different points than in a full two-storey design, and the engineer sizes the foundations to suit each part.

The roof junction

Where the single-storey roof meets the two-storey wall you need a sound weathering detail, usually a lead or similar flashing, and enough height for roof lights or a lantern. We set the roof falls and the upstairs window sill heights together so they do not clash.

How we work in Perth and Kinross

Understand the brief
At your home in Perth and Kinross we agree what you need: bedroom count, bathroom, kitchen space, and how much garden you want to keep.
Get it approved
Once you're happy with the design we submit it to the council for Perth and Kinross and deal with any questions from the planning officer.
Engineer it
Foundations sized for two floors, steels for any openings, and a building warrant, all before anyone starts on site.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.

Towns we cover in Perth and Kinross

Part single, part two-storey extensions in Perth and Kinross: questions

How much does a part single, part two-storey extension cost in Perth and Kinross?

In Scotland our guide is £1,880–£2,580 per m² including VAT, so about £67,500–£93,000 for a 6 m × 4 m ground floor and a first floor over half of it (36 m² in total). Essential and Premium specs move that by roughly 8% down or 20% up.

Can the single-storey part be deeper than the two-storey part?

With planning permission, yes, and that is often the point of the design: the ground floor projects further into the garden while the first floor stays back from neighbours. Under permitted development, the depth limits for extensions of more than one storey can apply to the whole extension, so we confirm which route applies before drawings are finalised.

Which side should the two-storey part go on?

Usually the side furthest from the nearest neighbour's windows, so the single-storey part sits nearest them and keeps their light. Other factors are where the stairs land upstairs, which room needs the extra space and where drains run. We sketch options at the design stage and explain which is most likely to be approved.

Will I need planning permission in Perth and Kinross?

Perth and Kinross 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.

Neighbouring areas

All extension services in Perth and Kinross · About part single, part two-storey extensions