First-floor extensions in the Highlands, Moray and Islands

The Highlands, Moray and Islands at a glance

Nation: Scotland
Price region: Scotland
Postcode areas: AB, HS, IV, KW, PH, ZE
Towns covered: 21 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 on the mainland; island and remote addresses by arrangement, with travel costs agreed first

What a first-floor extension involves

A first-floor extension is a new upstairs room built on top of an existing single-storey part of your house, such as a rear kitchen extension, a utility or a side annexe. It adds a bedroom, bathroom or study without enlarging the footprint. Whether it works depends mainly on whether the walls and foundations below can carry the extra load.

Across Highlands, Moray and Islands we cover Inverness (IV1), Elgin (IV30), Fort William (PH33), Nairn (IV12), Forres (IV36) and Buckie (AB56), plus the smaller places around them.

Guide price in Scotland

Most of the cost of a first-floor extension is set by its size and specification. For Highlands, Moray and Islands and the rest of Scotland, our guide is £1,690–£2,440 per m² including VAT, so about £23,500–£34,000 for 4 m × 3.5 m of new first-floor space (14 m²). Keep a contingency of around 10% for things nobody can see until the ground is opened up.

Spec	Per m²	Typical project
Essential	£1,560–£2,250 per m²	£22,000–£31,500
Standard	£1,690–£2,440 per m²	£23,500–£34,000
Premium	£2,030–£2,930 per m²	£28,500–£41,000

Rules in Scotland

In Scotland, permitted development for extensions of more than one storey (Class 1B) needs at least 10 m to every boundary and no part higher than the house. Most first-floor extensions cannot meet the 10 m test, so plan for a householder application (£371, decided within two months) and a building warrant before 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

Escape and fire safety

A new first-floor bedroom needs an escape window with a clear opening of at least 0.33 m², at least 450 mm wide and 450 mm high, with the bottom no more than 1,100 mm above the floor, unless there is a protected route to the stairs.

Can the existing structure take it?

Many single-storey extensions were built with foundations, walls and lintels sized for one storey. We find out what is there with trial holes and, where available, the original building standards drawings. The engineer then decides whether to reuse, strengthen or rebuild parts of the structure.

How we work in the Highlands, Moray and Islands

Start at your house
We come to your home in the Highlands, Moray and Islands, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Drawings and permission
Our designers produce plans and elevations, then we take care of planning or permitted development checks with the council covering Highlands, Moray and Islands.
Technical design
We prepare the building warrant drawings, structural calculations and specification so the build price can be fixed.
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 the Highlands, Moray and Islands

First-floor extensions in the Highlands, Moray and Islands: questions

How much does a first-floor extension cost in the Highlands, Moray and Islands?

In Scotland our guide is £1,690–£2,440 per m² including VAT, so about £23,500–£34,000 for 4 m × 3.5 m of new first-floor space (14 m²). Essential and Premium specs move that by roughly 8% down or 20% up.

Can I build on top of my existing single-storey extension?

Often yes, but only after the structure has been checked. Foundations, walls and lintels built for one storey may not carry two. We dig trial holes, look for the original a building warrant and ask the structural engineer to confirm what can stay, what needs strengthening and what must be rebuilt.

What happens to the room below while the first floor is built?

The old roof is removed, so the room below is exposed for a short period. We fit temporary weather protection, plan the work so the roof comes off only when the new structure is ready, and agree with you which rooms will be out of use and for roughly how long.

Will I need planning permission in the Highlands, Moray and Islands?

Highlands, Moray and Islands 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 the Highlands, Moray and Islands · About first-floor extensions