Double-storey extensions in Birmingham

What should you know before starting in Birmingham?

Planning permission from Birmingham City Council is the first hurdle for most double-storey extensions in Birmingham. Householder applications have an eight-week target for a decision, and Building Regulations approval and the Party Wall Act may also apply.

Under permitted development, a rear extension of more than one storey can project no more than 3 metres and must be at least 7 metres from the rear boundary.
A side extension of more than one storey always needs a householder planning application.
Scaffolding is usually up for most of the build, so think about access along the side of the house early.

Postcode districts: B1, B7, B9, B10, B12, B18
Planning and building control: Birmingham City Council
From our West Bromwich base: About 6 miles to the centre

Which options suit homes in Birmingham?

Two-storey side extension

Built over the side of the house, often where a driveway or old garage sits. It can create a garage, utility or study downstairs with a double bedroom above. Councils often expect the upper floor to be set back from the front and the roof to sit lower than the main ridge, so the design needs care to win approval.

Two-storey rear extension

Adds depth to both floors across the back of the house: a kitchen-diner below and a larger bedroom or new bathroom above. Permitted development only covers projections up to 3 metres and at least 7 metres from the rear boundary, so many rear builds still need planning. Overlooking and loss of light to neighbours are the usual tests.

What does your two-storey extension cost in Birmingham?

For a home in Birmingham, our guide range is £52,000–£135,000 depending on size and specification. A two-storey side extension on a three-bed semi, about 32 m² over two floors: usually £68,000–£88,000.

Guide prices for double-storey extensions
Option	Guide price	Good to know
Compact two-storey rear (20–28 m² total)	£52,000 – £72,000	Bigger kitchen below, bedroom or bathroom above
Two-storey side or rear (30–40 m² total)	£68,000 – £98,000	The usual size on a three-bed semi
Large or combined side and rear (45 m²+)	£95,000 – £135,000	More steel, a complex roof and a longer programme

Guide ranges include VAT where it applies. We confirm a fixed price for the agreed specification after visiting.

Double-storey extensions in Birmingham: common questions

What paperwork will I have at the end?

You'll get the building control completion certificate, the electrical installation certificate, your planning decision notice and the manufacturers' guarantee documents for windows, doors and roof products, with their terms set out in your quote. Keep these together, as a buyer's solicitor will ask for them when you sell. Ask us for current insurance details with your quote.

How do I book a survey in Birmingham?

Send the form on this page, use the guide-price tool or call 0800 088 6248 free. We'll ask a few questions about your two-storey extension and arrange a time to visit.

How long does a double-storey extension take?

Plan on 14–22 weeks on site, depending on size and roof complexity. Before that, allow time for drawings, a planning decision (councils aim to decide householder applications within 8 weeks), Building Regulations drawings and party wall notices. It's worth starting the design well ahead of when you need the space, because the approvals stage can take as long as the build.

Will I need permission from the council in Birmingham?

Usually both. Most two-storey extensions need a planning application to Birmingham City Council, and the structural work needs Building Regulations approval from its building control team or a registered building control approver.

Double-storey extensions across Birmingham

Choose your town for local details and postcodes:

Also covering nearby

Other home improvements in Birmingham

Want a guide figure first? Use our quote tool for your Birmingham extension, then book a survey for a fixed price for the agreed specification.