Dumbarton, Glasgow and the Clyde
Semi-detached rear extension in Dumbarton
Single or two-storey extensions for semi-detached houses, with side access and one party wall. If you live in Dumbarton and want to know what a semi-detached rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Dumbarton sits in Glasgow and the Clyde, with postcode districts including G82. Where a Dumbarton semi already has a small lean-to at the back, we usually replace it rather than extend it.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a semi-detached rear extension cost in Dumbarton?
Guide prices for a semi-detached rear extension in Dumbarton start from our Scotland rate of £1,800–£2,940 per square metre, including VAT. Prices in Scotland sit a little below our West Midlands baseline; building warrant fees and drawings are budgeted separately.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £21,500–£35,500 |
| 4 m wide × 5 m deep (20 m²) | £36,000–£59,000 |
| 4 m wide × 6 m deep (24 m²) | £43,500–£70,500 |
Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.
Do you need planning permission for a semi-detached rear extension in Dumbarton?
Planning for a semi-detached rear extension in Dumbarton follows the Scottish householder rules.
In Scotland a single-storey rear extension can be permitted development under Class 1A: eaves no higher than 3 metres and an overall height of 4 metres, and where any part is within 1 metre of a boundary it can project no more than 3 metres on a terraced house or 4 metres on other houses. The rights do not apply in conservation areas, and a building warrant is still needed before work starts.
In Scotland an extension of more than one storey is only permitted development (Class 1B) if no part is within 10 metres of any boundary and it is no higher than the existing house, so almost every two-storey rear extension needs planning permission and a building warrant.
Scotland has no larger-extension prior approval route; extensions beyond permitted development need a planning application.
Classes 1A and 1B do not apply in conservation areas, and listed buildings need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Dumbarton like to extend?
Post-war semis and terraces are common around Dumbarton, and many have room for a single-storey rear extension within Class 1A limits.
How a semi-detached rear extension in Dumbarton comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for the building warrant.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the accepted completion certificate.
Semi-detached rear extensions near Dumbarton
Neighbouring places we cover include Vale of Leven (1.9 miles) and Port Glasgow (4.6 miles).
- Semi-detached rear extension in Vale of Leven
- Semi-detached rear extension in Port Glasgow
- Semi-detached rear extension in Erskine
- Semi-detached rear extension in Clydebank
- Semi-detached rear extension in Greenock
Other work in Dumbarton:
FAQ
Semi-detached rear extension questions in Dumbarton
Can you match the brick or stone on my Dumbarton house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Single or two-storey on a semi?
Two-storey if you need bedrooms, single-storey if you need a bigger kitchen. Planning risk is lower for single-storey.
How much does a semi-detached rear extension cost in Dumbarton?
As a guide, £1,800–£2,940 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £21,500–£35,500 at that rate. Your written price follows the survey.
What postcode areas do you cover around Dumbarton?
Including G82, and the surrounding Glasgow and the Clyde area.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.