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.
In Dunbartonshire, we price a double-storey extension against our guide for Scotland, £58,000–£115,000 including VAT, then adjust it once we have surveyed your home. We work across Bearsden, Clydebank, Vale of Leven and Bishopbriggs and the rest of the county or region. Planning and building control requirements follow the rules for Scotland, and we look into your property's position before a written quote is sent.
- Guide price
- £58,000–£115,000 inc VAT
- Time on site
- 14–22 weeks on site
- Planning rules
- Scotland
- Price level
- About 4% below the national guide
- Towns listed
- 6
- Survey
- Free, with a written quote
Double-storey extensions prices in Dunbartonshire
Budgeting for a double-storey extension in Dunbartonshire? The numbers below include VAT and are adjusted for Scotland, where costs are about 4% below the national guide. The headline range is £58,000–£115,000. Nothing is final until we have measured up at a free survey and agreed the specification with you.
| Type of job | What it usually involves | Guide in Dunbartonshire |
|---|---|---|
| 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:
- Combined floor area across both storeys
- How the new roof joins the existing roof
- Foundation depth, ground conditions and drains to divert
- Scaffolding duration, access and the level of finishes
What’s included?
- Groundworks, foundations and below-ground drainage
- First-floor joists, stud walls and new openings upstairs
- Scaffolding for the full build, erected and inspected
- Electrics, plumbing and heating by qualified trades, with certificates
- Windows, external doors, plastering and internal doors
- Building control inspections and completion certificate
Housing across 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.
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.
The west of Scotland gets frequent heavy rain and wind, so driving-rain exposure is a key consideration for render and pointing.
Do you need permission in Dunbartonshire?
As Dunbartonshire is in Scotland, read the following with that system of planning and building control in mind. We check what applies to your house with the council before you receive a quote.
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.
From survey to handover
A visit to your home
A free survey comes first. It gives us what we need to price a double-storey extension properly, including dimensions, existing materials and access for deliveries, and gives you the chance to ask anything you like.
Price and scope agreed
After the survey we send a quote for a double-storey extension that fixes the price for the scope we've agreed. If you want to change materials or scope, we revise it in writing before anything is booked.
Plan and prepare
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.
Build and hand over
The job proceeds in the order set out in the programme, with dust and debris kept under control. Finally we tidy away, inspect the work together and pass the finished project over to you with its paperwork.
What you can expect from us
Frequently asked questions
Which postcodes in Dunbartonshire do you cover?
We cover G13, G60, G82 and 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.
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.
Is a double-storey extension better value than single-storey?
A double-storey extension usually gives better value per square metre than a single-storey one, because the same foundations and roof serve twice the floor area. The overall cost is higher, and planning can be harder because of the effect on neighbours. If you might want an extra bedroom later, building both floors now avoids a second round of disruption and scaffolding.
Will the extension affect my neighbours?
A double-storey extension can affect neighbours' light, outlook and privacy, which is why planning departments look closely at height, depth and window positions. Side windows facing neighbours often need obscure glass. Work near a shared wall may also need party wall notices; the Party Wall etc. Act 1996 applies in England and Wales only. We talk through these points early so the design is realistic.
Do I need planning permission in Dunbartonshire?
It depends on the work, the size of the project, your property type and whether the building is listed or in a conservation area. Dunbartonshire is in Scotland, so Scotland's rules apply. Many smaller jobs need no planning application, but some still need building control approval. We check what applies to your address before quoting.
Towns in Dunbartonshire
Our coverage for a double-storey extension in Dunbartonshire includes the towns listed here. Each page explains guide costs, typical timings and the neighbouring places we also serve.