A single-storey extension is a new ground-floor room built onto your house, usually at the rear or side, with its own foundations, walls and roof, creating a bigger kitchen, living space or bedroom without moving home.
Addresses across G82 fall within our coverage for a single-storey extension, so if your home is in Dumbarton we can arrange a survey on a day that works for you. We inspect the existing building, discuss materials and layout, and then price the agreed specification in writing. Expect a guide range of £33,500–£72,000 including VAT before that visit.
- Guide price
- £33,500–£72,000 inc VAT
- Time on site
- 10–16 weeks on site
- Postcodes
- G82
- Planning rules
- Scotland
- Local area
- West Dunbartonshire
- Survey
- Free, with a written quote
What should you budget for a single-storey extension in Dumbarton?
Below is a breakdown of typical costs for a single-storey extension in Dumbarton. Because rates in Scotland are about 4% below the national guide, the overall guide comes to £33,500–£72,000, including VAT. Size, materials and access move the figure, and a free-of-charge survey settles it.
| Type of job | What it usually involves | Guide in Dumbarton |
|---|---|---|
| Small extension (8–12m²) | A modest rear or side extension, such as a utility room or a slightly larger kitchen. | £21,000–£38,500 |
| Typical rear extension (15–25m²) | A kitchen-diner or family room with bifold doors and a rooflight or lantern. | £33,500–£72,000 |
| Large or wrap-around (30m² plus) | A wrap-around or wide rear extension, often with structural steelwork into the house. | £67,000–£125,000 |
The main things that change the figure:
- Floor area, shape and number of corners
- Roof type, rooflights, lanterns and the amount of glazing
- Steelwork needed to open into the existing house
- Finishes, kitchen, flooring and heating specification
What do you get?
- Groundworks, foundations and below-ground drainage
- Cavity walls built and insulated to building regulations
- Steel beams to open into the existing house
- Electrics and plumbing by qualified trades, with certificates
- Plastering, screed floor and internal doors
- Building control inspections and completion certificate
Homes in Dunbartonshire
Clydebank was heavily rebuilt after wartime bombing and has tenements and post-war estates, while Dumbarton has sandstone tenements and Victorian housing. Bearsden and Milngavie are known for Victorian villas and interwar bungalows, and Kirkintilloch mixes older terraces with post-war semis and newer developments.
The west of Scotland gets frequent heavy rain and wind, so driving-rain exposure is a key consideration for render and pointing.
That variety is why a guide price for a single-storey extension in Dumbarton is only a starting point; the survey shows what your particular property needs.
Planning and building rules in Dumbarton
Because Dumbarton falls under Scotland's rules, the guidance below is the version relevant to you. Before sending a price, we check your property's position with the council.
In Scotland, Class 1A permitted development covers some single-storey extensions, within limits on depth, height and distance from boundaries, and not in conservation areas or on flats. Anything outside those limits needs planning permission from the council.
A building warrant from the council’s building standards service is usually needed before work starts, and a completion certificate is accepted at the end. There is no Party Wall Act in Scotland; work near a boundary is agreed with neighbours under general law.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
The four stages
A visit to your home
Book a visit and we'll come to you. The survey covers measurements, the state of what's there now and any obvious constraints, so the price that follows is based on your actual home, not an average.
Written quote
Next you receive a written quote with a fixed price for the agreed specification. It lists what is included, what is not, and how payments are staged, so you can compare it properly.
Booking the work
With the quote agreed, we book the work in and handle preparation: permissions where needed, building control notifications, material orders and access arrangements for your Dumbarton property.
Finish and handover
Work goes ahead as scheduled and you deal with one contact throughout. When the last trade leaves, we clear and clean the site, talk you through what has been done and pass on any certificates and care instructions.
Why homeowners choose us
Frequently asked questions
Who do I deal with during the job?
One point of contact manages your project from survey to handover. They schedule the trades working under our contract, keep you updated on progress, and are the person to call with any question. You don't need to coordinate builders, electricians or decorators separately, because that is part of what we do.
Can you combine a single-storey extension with other work?
Yes. Because we manage several trades under one contract, we can plan a single-storey extension alongside other work on your Dumbarton home, such as new windows with rendering, or a kitchen refit with an extension. Combining jobs can reduce repeat set-up such as scaffolding, skips and access, and every element is listed and priced in the same written quote.
What is the Party Wall Act and does it apply to me?
The Party Wall etc. Act 1996 applies in England and Wales only. In England and Wales, it requires you to give notice to neighbours before certain work on or near a shared wall, such as digging foundations within 3m of their building and deeper than its footings. Neighbours can agree or appoint a surveyor. Scotland and Northern Ireland have no equivalent Act, though general rights still apply. We identify whether notices are needed during the survey.
Is a flat roof or a pitched roof better on an extension?
A flat roof is quicker to build and usually costs less, gives a clean modern look and works well with a roof lantern. A pitched roof matches the main house, sheds water faster and allows a vaulted ceiling, but it costs more and its height can affect neighbours. Modern flat roofs in EPDM rubber or GRP last well when properly detailed. Planning rules on height can also decide the choice.
Do I need an architect for an extension?
You need proper drawings for an extension, but not always a full architect service. A designer or architectural technician can produce planning and building regulations drawings, and a structural engineer provides beam and foundation calculations. If you already have drawings, we price from them. If not, we can arrange the drawings and calculations as part of the project so everything is coordinated from the start.
Near Dumbarton
We cover every part of Dumbarton, including G82, and nearby Vale of Leven, Erskine and Clydebank. Wherever you are within that patch, the survey is free and the quote comes to you in writing.