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.
Planning a double-storey extension for a home in Dunstable means making a handful of decisions about materials, layout, finish and timing. We help you work through them at a free survey, then confirm in writing what it will cost for the options you pick. Most projects of this type need 14–22 weeks on site, and we cover every LU6 address as well as the rest of Bedfordshire.
- Guide price
- £63,000–£126,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- LU6
- Planning rules
- England
- Local area
- Central Bedfordshire
- Survey
- Free, with a written quote
How much does a double-storey extension cost in Dunstable?
Every figure below is a guide for a double-storey extension in Dunstable, inclusive of VAT. Regional pricing for the East of England works out about 5% above the national guide, and the overall span is £63,000–£126,000. The survey costs you nothing, and after it we commit to a firm price for your specification in writing.
| Type of job | What it usually involves | Guide in Dunstable |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £42,000–£68,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £63,000–£126,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £105,000–£189,000 |
Your price depends mostly on:
- Combined floor area across both storeys
- 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
What does the job include in Dunstable?
- 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
- Scaffolding for the full build, erected and inspected
- Building control inspections and completion certificate
What are homes like around Dunstable?
Bedfordshire has a long brick-making history, and brick dominates: Victorian terraces in Bedford and Luton, interwar semis, large post-war estates around Luton and Dunstable, and newer developments near Bedford and Biggleswade. Villages in the north of the county keep limestone cottages, with timber framing and thatch scattered across older settlements.
Terraced houses here often benefit from rear extensions, loft rooms and repointing. Interwar and post-war semis commonly suit kitchen extensions, porches and garage conversions, while older village properties may call for lime plastering and sympathetic window replacements.
So when we survey a Dunstable 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 Dunstable
Each UK nation sets its own consent rules, and Dunstable is in England. What follows is a plain summary; we check the specifics for your property with the council before pricing anything.
In England, a two-storey rear extension can only be permitted development if it is no more than 3 m deep, at least 7 m from the rear boundary and finished to match the house. Most double-storey and all two-storey side extensions need full planning permission.
Building Regulations approval is needed, with structural calculations for beams, foundations and the roof. The Party Wall etc. Act 1996 often applies on semi-detached and terraced houses.
Rules change and every property is different, so we check the planning history and constraints for your address before we quote.
The four stages
Free site survey
It starts with a survey at the property, free of charge. We check condition, access and services, ask how you want the finished result to look, and answer any questions you have about a double-storey extension.
Price and scope agreed
We turn the survey notes into a written quote. The price is fixed for the specification we agree, and the document sets out materials, scope and payment stages in plain language.
Getting ready
Once you accept, we agree start dates, order materials and deal with any planning, building control or neighbour notices the job needs. You'll know who is coming and when before work begins.
Finish and handover
During the work we protect the areas around it and tidy up at the end of each day. Once complete, we check the finish, remove our materials and hand over paperwork such as building control sign-off where it applies.
Why homeowners choose us
Questions about a double-storey extension in Dunstable
Do I need planning permission in Dunstable?
It depends on the work, the size of the project, your property type and whether the building is listed or in a conservation area. Dunstable is in England, so England'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.
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.
How much does a double-storey extension cost?
A typical double-storey extension of 30–40m² across both floors costs £63,000–£126,000, built to a plastered finish. As a rough guide, allow around £1,400–£2,600 per square metre plus fixed costs for groundworks, scaffolding and fees. The second storey usually costs less per square metre than the first, because foundations and roof are shared. Bathrooms upstairs and a complex roof add most. We confirm a fixed price after the survey.
How much will a double-storey extension cost in Dunstable?
As a guide, expect to pay £63,000–£126,000 including VAT for a double-storey extension in Dunstable. That range is adjusted for the East of England, which runs about 5% above the national guide. Where your project lands depends on size, materials, access and the condition of what is already there. We confirm a fixed price in writing after a free survey of your home.
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.
Near Dunstable
Dunstable and its LU6 postcodes are part of our coverage. Homeowners in Luton, Leighton Buzzard and Harpenden can also book a free survey with us and receive a written price for their job.