First-floor extensions in Renfrew

Quick reference for homeowners in Renfrew.

Postcode districts: PA4
County / area: Renfrewshire and Inverclyde, Scotland
Price region: Scotland
Guide price: £23,500–£34,000 (£1,690–£2,440 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: Clydebank (2.1 miles), Erskine (3 miles), Dalmuir (3 miles)
Distance to Paisley: about 3.2 miles
First visit: Free, no obligation

About a first-floor extension

A first-floor extension suits you if your house already has a single-storey extension and you need more space upstairs. You get a structural check of the existing walls and foundations, a design that ties the new floor into the house, the approvals your nation needs, a building warrant and the build, managed by us and carried out by vetted teams working under S&K.

We cover Renfrew (PA4) and the places around it, including Clydebank (2.1 miles), Erskine (3.0 miles) and Dalmuir.

What it costs in Renfrew

In Scotland, which includes Renfrew, we'd expect a first-floor extension to cost around £23,500–£34,000 for 4 m × 3.5 m of new first-floor space (14 m²), or £1,690–£2,440 per m² including VAT. Kitchens, bathroom fittings and flooring are priced separately so you can compare like with like.

Spec	Per m²	4 m × 3.5 m of new first-floor space (14 m²)
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

Planning and building standards in Renfrew

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.

Design points for Renfrew homes

Tying into the house

The new floor and walls must line up with the existing first floor, often through a new opening in the rear wall above the old one. Floor levels, the position of upstairs windows and the existing roof all affect where the opening can go, so we survey both floors carefully.

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'd run your project

Start at your house
We come to your home in Renfrew, measure up, check the ground floor walls and roof structure, and note anything near the boundaries.
Choose the approval route
Some designs fit permitted development, most need a householder application. We decide which applies in Scotland before drawing in detail.
Engineer it
Foundations sized for two floors, steels for any openings, and a building warrant, all before anyone starts on site.
Finish and certify
Second fix, plastering and making good, then the council's final building standards inspection and the completion paperwork.

Questions about first-floor extensions in Renfrew

Do I need planning permission for a first-floor extension in Renfrew?

Renfrew 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 first-floor extension cost in Renfrew?

Our guide for Scotland, which covers Renfrew, is £1,690–£2,440 per m² including VAT. A typical project with 4 m × 3.5 m of new first-floor space (14 m²) comes to about £23,500–£34,000. Design and approval fees are extra, and we fix the build price in writing once the design is agreed.

Who handles building standards for a project in Renfrew?

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.

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.

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.

Nearby

Nearby towns we cover for first-floor extensions:

Other extensions in Renfrew

All two-storey extension services in Renfrew · First-floor extensions across Renfrewshire and Inverclyde

Tell us about your house in Renfrew and we'll call you back to arrange a free, no-obligation visit.