What is a single-storey extension?
A single-storey extension is a ground-floor addition, usually at the rear of a house, that enlarges a kitchen, living or dining space. Most are built with cavity walls on concrete foundations and finished with a flat roof and roof lantern or a pitched tiled roof.
How much does a single-storey extension cost in Erskine?
In Erskine, a single-storey extension typically costs £1,900–£2,800 per m² of floor area, including VAT at 20% (standard rate). For a typical 20 m² project that is roughly £38,000–£56,000. Building costs in Scotland are close to the UK average, so the figures for Erskine are close to our national guide. Design, structural calculations and council fees are extra.
| Size or type | Guide range |
|---|---|
| Smaller project (14 m²) | £26,500–£39,000 |
| Typical project (20 m²) | £38,000–£56,000 |
| Larger project (28 m²) | £53,000–£78,500 |
| Rate per m² | £1,900–£2,800 |
The main things that change the cost:
- Roof type and the size of any lantern or roof windows
- Glazing: sliding and bifold doors cost more than French doors
- How much of the existing house is opened up
- Kitchen, flooring and finishes, which we can include or leave to you
For a figure based on your own measurements, try the guide price tool, then book a free home visit for a fixed quote.
Do you need planning permission for a single-storey extension in Erskine?
Approvals for a single-storey extension in Erskine follow the rules for Scotland. In Scotland a single-storey extension is often permitted development (Class 1A): where any part is within 1 metre of a boundary, it can project up to 3 metres from the rear wall of a terraced house or 4 metres on other houses, with eaves no higher than 3 metres, an overall height of 4 metres and no more than half the front or rear garden covered. The rights do not apply in conservation areas or to flats, and a building warrant will usually still be needed before work starts.
In Scotland a building warrant is needed before work starts on most extensions, loft conversions and conversions. It is issued by the council’s building standards service. When the work is finished, a completion certificate is submitted and accepted by the council after inspection.
Our first visit includes a check of your planning history, so you know the route before paying for drawings.
What we handle
From survey to sign-off, the job normally involves:
- Measured survey and design drawings
- Knock-through to the existing house with steel beams
- Cavity walls, insulation and roof to current building regulations
- First and second fix electrics, heating and plastering
- Structural calculations for steels and lintels
- Building control inspections and completion certificate
How long does it take?
Expect 10 to 14 weeks on site for a typical rear extension, after approvals. Allow time beforehand for drawings and approvals, usually 6 to 12 weeks.
Building in Erskine
Scotland’s housing ranges from sandstone tenements and villas to post-war and modern estates, and the building warrant system shapes how projects are planned.
From PA8 outwards, we take on projects throughout Erskine and the surrounding parts of Renfrewshire and Inverclyde.
How it works
- 01
Survey and brief
We visit, discuss your ideas and budget, and survey the property or site at no cost.
- 02
Drawings and written quote
We prepare the design and give you a written, itemised quote with inclusions and exclusions.
- 03
Approvals
Planning or permitted development confirmation, building regulations and any party wall matters.
- 04
Build and handover
Work follows the agreed programme, with inspections along the way and a completion certificate at the end.
Questions about single-storey extensions in Erskine
Can I stay in the house during the build?
Usually yes. We build the shell before opening up the back wall, so the house stays weathertight for most of the job. There will be a few weeks when the kitchen or back room is out of use.
Do I need planning permission for a single-storey extension in Erskine?
In Scotland a single-storey extension is often permitted development (Class 1A): where any part is within 1 metre of a boundary, it can project up to 3 metres from the rear wall of a terraced house or 4 metres on other houses, with eaves no higher than 3 metres, an overall height of 4 metres and no more than half the front or rear garden covered. The rights do not apply in conservation areas or to flats, and a building warrant will usually still be needed before work starts.
Is VAT charged on an extension?
Yes. Building work on an existing home is standard-rated, so VAT at 20% applies. Our guide prices include it.
How long does a single-storey extension take in Erskine?
Typically 10 to 14 weeks on site for a typical rear extension, after approvals. Design and approvals beforehand usually take 6 to 12 weeks.
What is a build-over agreement?
If a public sewer runs within 3 metres of the extension, the water company normally has to agree to the work before it starts. We check sewer records during design and apply where needed.
How much does a single-storey extension cost in Erskine?
In Erskine, a single-storey extension typically costs £1,900–£2,800 per m² of floor area, including VAT at 20% (standard rate). A typical 20 m² project comes to roughly £38,000–£56,000. Your fixed price depends on the survey and drawings.