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.
Addresses across B1, B2, B3 and B4 fall within our coverage for a double-storey extension, so if your home is in Birmingham we can arrange a survey on a day that works for you. We inspect the existing building, discuss materials and layout, and then price the agreed specification in writing. Expect a guide range of £59,000–£118,000 including VAT before that visit.
- Guide price
- £59,000–£118,000 inc VAT
- Time on site
- 14–22 weeks on site
- Postcodes
- B1, B2, B3, B4 and B5
- Planning rules
- England
- Local area
- West Midlands
- Survey
- Free, with a written quote
What should you budget for a double-storey extension in Birmingham?
Below is a breakdown of typical costs for a double-storey extension in Birmingham. Because rates in the West Midlands are about 2% below the national guide, the overall guide comes to £59,000–£118,000, 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 Birmingham |
|---|---|---|
| Small (15–20m² total) | A compact rear or side extension adding a small room on each floor. | £39,000–£64,000 |
| Typical (30–40m² total) | A larger kitchen or living room below with a double bedroom or en-suite above. | £59,000–£118,000 |
| Large (50m² plus total) | Wide or deep extensions, often with a new bathroom, steelwork and high-spec glazing. | £98,000–£176,000 |
Your price depends mostly on:
- 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’s included?
- 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
Homes in West Midlands
Red-brick Victorian and Edwardian terraces are common in the inner areas of Birmingham, Wolverhampton and the Black Country, ringed by large swathes of 1930s semis with bay windows and hipped roofs. You'll also find post-war council estates, some system-built blocks, Coventry's rebuilt centre and larger detached homes in Solihull and Sutton Coldfield.
An inland climate with regular winter frosts means freeze-thaw damage to soft brick and old mortar is a common reason for repointing and render repairs.
Whatever era your Birmingham home dates from, we plan a double-storey extension around how it is actually built rather than a one-size-fits-all specification.
Permissions for a double-storey extension in Birmingham
England, Wales, Scotland and Northern Ireland each handle planning a little differently. Birmingham 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.
From survey to handover
We look at the job
We arrange a free site survey on a date convenient to you. We measure up, look at the existing structure and access, and discuss your plans for a double-storey extension so the price reflects your home.
Written quote
You get the price in writing, itemised so you can see where the money goes. As long as the specification stays the same, that is the price you pay for a double-storey extension.
Getting ready
Before anyone starts, we confirm the programme in writing, check whether consents are required and arrange deliveries. If a skip or scaffolding on the road needs a permit, we apply for it.
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 Birmingham
Can I stay at home during the work?
In most cases, yes. Most people can live at home throughout, and we plan the work to keep disruption down by protecting floors, agreeing working hours and keeping access routes clear. Bigger jobs affecting kitchens, bathrooms or heating may mean a short spell with reduced facilities, and we talk this through with you at the survey.
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.
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.
Do you cover Aston, Smethwick and Washwood Heath?
Yes. As well as Birmingham, we cover Aston, Smethwick and Washwood Heath and the rest of West Midlands. Our coverage is UK-wide, so the process is the same wherever you are: a free site survey, a quote in writing that fixes the price for the agreed scope, and one point of contact while the work is planned and carried out.
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.
Near Birmingham
Our coverage in Birmingham includes B1, B2, B3 and B4. We also travel to Aston, Smethwick and Washwood Heath, so neighbouring addresses are looked after on exactly the same terms as those in town.