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.
We arrange a double-storey extension for homeowners in Helensburgh and the wider Argyll and Bute. The job is planned, priced and managed by us and carried out by tradespeople engaged under our contract, so there is one agreement and one contact. On a typical home the work takes 14–22 weeks on site, and guide pricing in Scotland is £58,000–£115,000, VAT included.
- Guide price
- £58,000–£115,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- G84
- Planning rules
- Scotland
- Local area
- Argyll and Bute
- Survey
- Free, with a written quote
Double-storey extensions prices in Helensburgh
What should you budget for a double-storey extension in Helensburgh? Use the figures below as a starting point. Prices in Scotland sit about 4% below the national guide, so the range here is £58,000–£115,000 including VAT. Your fixed price comes in writing once we've surveyed the property, at no charge.
| Type of job | What it usually involves | Guide in Helensburgh |
|---|---|---|
| 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 |
Expect these to shape the final quote:
- Combined floor area across both storeys
- 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 Helensburgh?
- 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
- 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 in Helensburgh
Much of Argyll and Bute is rural and coastal, with whitewashed or harled stone cottages, slate roofs and island homes. Helensburgh has Victorian villas, Oban, Dunoon and Rothesay have Victorian seaside terraces, and post-war and newer housing surrounds the main towns.
Stone cottages need lime harling, repointing and slate roof repairs; villas may need roof and window renewal. Island and remote properties need the programme planned around ferries, deliveries and weather.
These patterns matter for a double-storey extension: older walls, roofs and floors in Helensburgh can need different materials or extra preparation compared with newer homes.
Do you need permission in Helensburgh?
Each UK nation sets its own consent rules, and Helensburgh is in Scotland. What follows is a plain summary; we check the specifics for your property with the council before pricing anything.
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
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.
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.
Getting ready
We handle the paperwork side: checking whether planning permission or building control approval is needed, submitting applications where they are, and scheduling the trades and materials around your dates.
Finish and handover
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
Frequently asked questions
Can we live at home while it is built?
Most families stay at home during a double-storey extension. The new structure is built outside first, and we only break through into the existing rooms near the end, usually one floor at a time. Upstairs, this may mean a bedroom is out of use for a week or two. We fit dust screens, protect floors and stairs, and plan any time without water or power in advance.
How is the new roof joined to the existing house?
The new roof is usually tied into the existing roof so the two read as one. On a rear extension this often means a lower ridge or a hipped end, with valleys where the slopes meet. We strip back some existing tiles, fix new rafters and battens, and lay matching tiles or slates. Lead or proprietary flashings seal the junctions so water runs off properly.
What happens at the survey?
We visit your home at a time that suits you, look at the area involved, take measurements and check access, condition and any services that might be affected. We talk through what you want from a double-storey extension, explain the options and answer questions. There is no charge and no obligation; afterwards we send a written quote.
Is the price fixed?
Yes, for the specification we agree. Your written quote sets out exactly what is included at a fixed price. It only changes if you ask for something different, or if a problem the survey could not reasonably reveal later needs extra work. In either case we explain the change and confirm it in writing before going ahead.
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.
Nearby towns
From G84 to the edges of Helensburgh and on into Greenock, Vale of Leven and Dumbarton, we can arrange a site visit and a written quote for your project, planned around dates that work for you.