A double-storey extension adds two floors of new space to your house in one build, typically a larger kitchen or living room downstairs with an extra bedroom, bathroom or en-suite above, sharing one set of foundations and one roof.
For a homeowner in Bishopbriggs, planning a double-storey extension tends to begin with two questions: what will it cost, and how disruptive will it be? Our guide range is £58,000–£115,000 including VAT, and a typical job runs to 14–22 weeks on site. Both numbers firm up once we have seen the property, measured up and agreed exactly what is included.
- Guide price
- £58,000–£115,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- G64
- Planning rules
- Scotland
- Local area
- East Dunbartonshire
- Survey
- Free, with a written quote
What should you budget for a double-storey extension in Bishopbriggs?
Below is a breakdown of typical costs for a double-storey extension in Bishopbriggs. Because rates in Scotland are about 4% below the national guide, the overall guide comes to £58,000–£115,000, 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 Bishopbriggs |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £38,500–£62,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £58,000–£115,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £96,000–£173,000 |
The main things that change the figure:
- How the new roof joins the existing roof
- Bathrooms, en-suites and plumbing on the upper floor
- Foundation depth, ground conditions and drains to divert
- Scaffolding duration, access and the level of finishes
What does the job include in Bishopbriggs?
- Groundworks, foundations and below-ground drainage
- Insulated cavity walls with brick or render to match the house
- First-floor joists, stud walls and new openings upstairs
- Roof structure tied into the existing roof, tiled to match
- Windows, external doors, plastering and internal doors
- Building control inspections and completion certificate
Building in Bishopbriggs
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.
Bungalows commonly suit loft conversions with dormers, and villas often take kitchen extensions and landscaping. Tenement flats may need window replacement, and harled homes often need re-rendering.
So when we survey a Bishopbriggs property for a double-storey extension, the first step is working out how it was built and what has been changed since.
Planning and building rules in Bishopbriggs
England, Wales, Scotland and Northern Ireland each handle planning a little differently. Bishopbriggs comes under Scotland, covered below, and we raise any questions with the council before your quote is finalised.
In Scotland, extensions of more than one storey are only permitted development in narrow cases (Class 1B, well away from the boundary they face and outside conservation areas), so most need planning permission.
A building warrant is required before work starts. Scotland has no Party Wall Act; neighbour and title issues are handled under general law.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
How does the job run?
Free site survey
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
The quote arrives in writing, not over the phone. It covers the full scope, the finishes you've chosen, any exclusions and the payment schedule, with a fixed price tied to that specification.
Dates and permissions
Next comes planning the work itself. We set a start date that suits you, line up the right trades, and make sure any approvals for a double-storey extension are in place before the first day on site.
On site to finish
The work is carried out to the agreed specification, with floors and furniture protected and the site kept tidy. At the end we clean up, walk through the finished job with you and hand over any certificates.
What you can expect from us
Questions about a double-storey extension in Bishopbriggs
Do I need planning permission for a two-storey extension?
Most two-storey extensions need planning permission, but it depends on the size, height and position, your home's location, whether it is listed or in a conservation area, and which UK nation you are in. In England, a two-storey rear extension can sometimes be built under permitted development if it is no deeper than 3m and at least 7m from the rear boundary. We check what applies before quoting.
How long does a double-storey extension take?
A double-storey extension typically takes 14–22 weeks on site, depending on size, roof design and weather. Foundations and ground-floor walls come first, then the first-floor joists, upper walls and roof. Once it is weathertight, electrics, plumbing, plastering and finishes follow. Allow extra time beforehand for drawings, calculations and approvals. We give you a stage-by-stage programme with your quote.
Can the new upstairs room have its own bathroom?
A new upstairs room can usually have an en-suite, provided waste pipes can reach the soil stack or a new one can be installed. Running the waste pipe to the right falls is the main design question, and a pumped system is an option where gravity will not work. We plan bathroom positions at the design stage so pipes, ventilation and insulation are built in rather than added later.
Can you combine a double-storey extension with other work?
Yes. Because we manage several trades under one contract, we can plan a double-storey extension alongside other work on your Bishopbriggs 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.
Which postcodes in Bishopbriggs do you cover?
We cover G64, along with the rest of Dunbartonshire. If your postcode is not listed, get in touch anyway: our coverage is UK-wide, and we can usually arrange a survey wherever you live. Enter your postcode in the guide-price tool or contact form and we will confirm.
Near Bishopbriggs
Whether you're in the centre of Bishopbriggs or on its outskirts, G64 addresses are covered. We extend the same service, and the same fixed-price approach, to Kirkintilloch, Bearsden and Rutherglen.