Double-storey extensions in Castle Vale

Planning your two-storey extension in Castle Vale

Most two-storey extensions in Castle Vale need a planning application to Birmingham City Council. A two-storey rear extension can sometimes be permitted development, but only if it is no more than 3 m deep and at least 7 m from the rear boundary, among other conditions. Building Regulations approval is needed either way.

New first-floor bedrooms normally need an escape window with at least 0.33 m² of clear openable area.
The householder planning fee in England is £548 from April 2026, paid to Birmingham City Council when you apply.
Scaffolding is usually up for most of the build, so think about access along the side of the house early.

Postcode district: B35
Planning and building control: Birmingham City Council
From our West Bromwich base: 9 miles

Choices to weigh up in Castle Vale

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.

Guide prices for Castle Vale

Guide prices start at £52,000 and run to £135,000 depending on size and specification. A two-storey side extension on a three-bed semi, about 32 m² over two floors: around £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. A free survey turns this guide into a fixed, itemised price.

Your questions answered

Is a double-storey extension better value than a single-storey one?

Per square metre, usually yes. Foundations and roofs are the expensive parts of any extension, and on a two-storey build they serve twice the floor area. You'll pay more in total and planning is less certain, but if you need a bedroom as well as downstairs space, building both together normally costs less than two separate projects years apart.

Do you cover Castle Vale?

Yes. Castle Vale (B35) is about 9 miles from our West Bromwich base and inside the area we cover. Call 0800 088 6248 or send the form on this page to book a free survey.

What will the council look at when deciding planning?

Councils judge two-storey extensions mainly on their effect on neighbours and the street. They look at loss of light and outlook next door, overlooking from upstairs windows, and whether the extension sits comfortably with the house, often expecting side extensions to be set back and lower than the main roof. Many councils publish householder design guides, and following yours closely improves the chance of approval.

Does Birmingham City Council need to approve my two-storey extension?

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.

Also covering nearby

More services in Castle Vale

Call 0800 088 6248 or send us your postcode, and we'll arrange a time to look at the house.