Dumbarton flat roof extensions, designed and built
Dumbarton homeowners can use us for the whole flat roof extension project: survey, design, planning or permitted development checks, the building warrant and the build itself.
- Guide price in DumbartonFrom £20,500 inc VAT
- PlanningScottish householder rules; building warrant needed
- Build time10–16 weeks on site
- Postcode districtsG82
Planning rules that apply in Dumbarton
In Scotland, householder permitted development rules (Class 1A for single-storey ground-floor extensions and Class 1B for extensions of more than one storey) allow some smaller extensions without a planning application, within limits on depth, height and distance from the boundary. Conservation areas and listed buildings are more restricted. Separately, almost every extension needs a building warrant from the council before work starts.
Homes in conservation areas, national scenic areas and listed buildings have tighter rules, so we always check the property's status and planning history before design starts.
Scotland has no Party Wall Act. Where work affects a shared wall or a neighbour's land, we agree access, protection and making good with your neighbour in writing before work starts.
Building close to a public sewer needs the agreement of Scottish Water, which we check during design.
Applications are decided by your council as planning authority.
Extensions in and around Dumbarton
Across G82, we can visit, measure and advise. Neighbouring towns we cover include Vale of Leven (2 miles), Clydebank (7 miles), Bearsden (9 miles), Bishopbriggs (14 miles).
Erskine, in Renfrewshire and Inverclyde, is roughly 6 miles from Dumbarton and also on our list. Scotland's housing includes sandstone villas, terraces and tenements in the cities and plenty of post-war and modern houses and bungalows elsewhere. A building warrant is needed before work starts.
Flat roof extension prices in Dumbarton
Labour and material costs vary across the UK, so for Dumbarton we use our Scotland factor (×0.98). The ranges include VAT and exclude design, structural and council fees.
Typical rates in Dumbarton: £1,720 to £3,280 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 4 m 12 m² | £20,500 – £24,500 | £24,000 – £31,000 | £30,500 – £39,500 |
| 4 m × 5 m 20 m² | £34,000 – £40,500 | £40,000 – £51,000 | £50,500 – £66,000 |
| 5 m × 6 m 30 m² | £51,000 – £60,500 | £60,000 – £76,500 | £76,000 – £98,500 |
Try the guide-price tool to see a range for your own size and finish.
Is a flat roof extension right for your house?
- Modern and 1930s onwards houses
- Extensions under first-floor windows where a pitch will not fit
- Homeowners who want maximum light from above
Height is often what decides a flat roof. Under first-floor windows, a pitched roof may not fit at all; a flat roof keeps the extension low while still giving a good ceiling height inside.
Our process, step by step
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Flat roof extension questions answered
How long does a flat roof extension take to build in Dumbarton?
On site, typically 10 to 16 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Can I see a price before committing to anything?
Yes. The guide prices on this page are adjusted for Dumbarton, and the guide-price tool gives a range for your own size. After the survey you get a written price before anything is agreed.
Will my neighbours in Dumbarton be involved?
If a planning application is needed, the council notifies neighbours. Where work is close to a shared boundary, we agree access and protection with them in writing.
Can I walk on a flat roof extension?
Only for maintenance unless it is designed as a terrace. A roof terrace or balcony needs planning permission and a different structure.
Are flat roof extensions cheaper?
Usually slightly, because there is less roof structure and no tiles. Our guide range is about £1,720 to £3,280 per m² including VAT.
Book a free site visit in Dumbarton
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.