Annexe extensions in Dumbarton: design, approvals and build
From the first sketch to final sign-off, we plan and build annexe extensions in Dumbarton and the surrounding Dunbartonshire area.
- Guide price in DumbartonFrom £53,500 inc VAT
- PlanningScottish householder rules; building warrant needed
- Build time16–24 weeks on site
- Postcode districtsG82
Included in a typical project
- Fire separation and alarms to building regulations
- Kitchenette, shower room and bedroom finish
- Separate or shared heating and hot water
- Design for accessibility: level thresholds, wider doors, walk-in shower
Accessibility is cheaper to design in than to retrofit. Level access, a 900 mm door width, a level-access shower and space to turn a wheelchair can all be planned into the footprint for little extra cost.
Annexe extension prices in Dumbarton
For Dumbarton we adjust our national guide rates by ×0.98, the factor we use for Scotland. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Dumbarton: £1,960 to £3,720 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| Studio annexe 25 m² | £53,500 – £67,500 | £58,500 – £73,500 | £73,500 – £93,500 |
| One-bedroom annexe 35 m² | £68,500 – £86,000 | £82,000 – £103,000 | £102,500 – £130,500 |
| Larger annexe 45 m² | £88,000 – £110,500 | £105,500 – £132,500 | £132,000 – £168,000 |
Try the guide-price tool to see a range for your own size and finish.
Will the council need to approve it?
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.
The planning position for a specific Dumbarton address depends on its history and any designations, which is why we check it at the first visit.
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.
Working in Dumbarton
We cover Dumbarton and the postcode districts G82. Nearby, we also take on projects in 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. Across Scotland, extensions follow Scottish planning and building standards, including the building warrant process, which we build into the programme from the start.
From first visit to completion
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
We visit your Dumbarton home, measure up, talk through what you want and check the planning position.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions people ask about annexe extensions
How long does an annexe extension take to build in Dumbarton?
On site, typically 16 to 24 weeks once approvals are in place. Before that, allow 10–16 weeks design and approvals.
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.
Do you cover all of Dumbarton?
Yes. We cover Dumbarton and the surrounding parts of Dunbartonshire. Site visits are free and there is no obligation.
Does an annexe extension need planning permission?
Usually yes, because of its size and the way it will be used. Councils check that it stays ancillary to the main house, so the application must describe the use clearly.
How much does an annexe extension cost?
Our guide range is about £1,960 to £3,720 per m² including VAT. A one-bedroom annexe of about 35 m² is typically £82,000 to £103,000 at standard spec in Dumbarton.
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.