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 take on a double-storey extension throughout Derby and the surrounding DE1, DE21, DE22 and DE23 postcodes, as well as in Belper, Ilkeston and Heanor. The guide range for this work in the East Midlands is £58,000–£115,000 including VAT; where your project falls depends on its size, the materials you pick and how easy the site is to reach. A free survey turns that range into a fixed figure.
- Guide price
- £58,000–£115,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- DE1, DE21, DE22, DE23 and DE24
- Planning rules
- England
- Local area
- Derbyshire
- Survey
- Free, with a written quote
What should you budget for a double-storey extension in Derby?
Every figure below is a guide for a double-storey extension in Derby, inclusive of VAT. Regional pricing for the East Midlands works out about 4% below the national guide, and the overall span is £58,000–£115,000. 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 Derby |
|---|---|---|
| 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 does the job include in Derby?
- Groundworks, foundations and below-ground drainage
- Insulated cavity walls with brick or render to match the house
- 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
- Building control inspections and completion certificate
Local housing and a double-storey extension
Derby has wide areas of Victorian red-brick terraces and interwar semis, while Peak District villages use gritstone and limestone under stone-slate or Welsh slate roofs. Former mining towns in the north-east of the county have brick terraces and post-war housing built for mining communities, and modern estates have grown around Derby, Chesterfield and the M1 corridor.
The High Peak gets heavy rain, snow and frequent frost, while the lower Trent valley is milder; old mine workings can also affect ground conditions in places.
Knowing the typical building types in Derbyshire helps, but a survey of your own home in Derby is what decides the right approach to a double-storey extension.
Planning and building rules in Derby
England, Wales, Scotland and Northern Ireland each handle planning a little differently. Derby comes under England, covered below, and we raise any questions with the council before your quote is finalised.
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
Survey and measure
We begin by looking at the job in person. During the free survey we discuss options, materials and budget for a double-storey extension, and photograph or measure anything the quote needs to reflect.
Written quote
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.
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 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.
Working with SK Home Improvements
Frequently asked questions
Do I need planning permission in Derby?
It depends on the work, the size of the project, your property type and whether the building is listed or in a conservation area. Derby 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 much does a double-storey extension cost?
A typical double-storey extension of 30–40m² across both floors costs £58,000–£115,000, 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.
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.
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.
How long will a double-storey extension take?
On a typical home, allow 14–22 weeks on site. Larger projects, older buildings and extra work found once things are opened up can extend that, while simpler jobs may be shorter. Your quote includes an estimate of time on site, and your point of contact keeps you updated on the programme as the work progresses.
Also covering areas around Derby
Homes across DE1, DE21, DE22 and DE23 in Derby are within our coverage, as are those in Belper, Ilkeston and Heanor. If you are just outside these areas, ask anyway, because we work right across the UK.