Two-storey extensions for detached houses in Washwood Heath

Before you start in Washwood Heath, here's what applies.

Postcode districts: B8, B9, B23 and B24
County / area: West Midlands, England
Price region: West Midlands
Guide price: £86,000–£115,500 (£2,050–£2,750 per m²)
Approval route: Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission.
Nearest towns: Castle Vale (1.8 miles), Aston (2.4 miles), Birmingham (3.4 miles)
Distance to Birmingham: about 3.4 miles
First visit: Free, no obligation

About a two-storey extension for a detached house

A two-storey extension for a detached house is a two-floor addition to the side, rear or both of a house that stands on its own plot. Detached houses often have room on more than one side, so there is more choice of layout and fewer shared-wall issues. The design still needs to respect boundaries, neighbours' windows and the look of the house.

We cover Washwood Heath (B8, B9, B23 and B24) and the places around it, including Castle Vale (1.8 miles), Aston (2.4 miles) and Birmingham.

What it costs in Washwood Heath

For budgeting in Washwood Heath, allow around £86,000–£115,500 for a two-storey extension for a detached house with a 3 m × 7 m footprint on two floors (42 m² of new floor space). That's based on £2,050–£2,750 per m² including VAT for the West Midlands. Design fees, structural calculations and approval fees are separate and listed on our prices page.

Spec	Per m²	A 3 m × 7 m footprint on two floors (42 m² of new floor space)
Essential	£1,890–£2,530 per m²	£79,000–£106,500
Standard	£2,050–£2,750 per m²	£86,000–£115,500
Premium	£2,460–£3,300 per m²	£103,500–£138,500

Planning and building regulations in Washwood Heath

In England, a two-storey rear extension on a detached house can be permitted development within 3 m of the original rear wall and at least 7 m from the rear boundary, with matching roof pitch and materials, outside protected areas. Any two-storey side or wraparound extension needs planning permission, costing £548 (or £575 for applications made from 8 December 2026), with a decision due within 8 weeks of validation.

Approval in England: Householder planning application: £548 (or £575 for applications made from 8 December 2026). Lawful development certificate: £274 (about £288 for applications from 8 December 2026). Councils should decide householder applications within 8 weeks of validation.

Building regulations: Building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end.

Design points for Washwood Heath homes

Choosing the best side

On a detached house you can often extend on either side or the rear. We look at orientation for daylight, where the stairs and landing are, the distance to each boundary, drains and trees, so the extension goes where it adds the most useful space.

Larger spans and steelwork

Bigger extensions often mean wider openings and longer spans, which need more steel and sometimes a steel frame. The engineer designs these early, because the size of the steel affects ceiling heights, floor depths and the cost.

How we'd run your project

Visit and first ideas
One of our team visits your house in Washwood Heath, checks the walls, roof and drains, and sketches out options with you.
Get it approved
Once you're happy with the design we submit it to the council for Washwood Heath and deal with any questions from the planning officer.
Technical design
We prepare the building regulations drawings, structural calculations and specification so the build price can be fixed.
Build
Foundations, walls, floor, roof, windows, then first and second fix. We break through into the house as late as we can.

Questions about two-storey extensions for detached houses in Washwood Heath

Do I need planning permission for a two-storey extension for a detached house in Washwood Heath?

Washwood Heath is in England, so England planning rules apply. Depends on position: a two-storey rear extension may be permitted development (3 m deep, 7 m from the rear boundary); a two-storey side extension needs planning permission. If in doubt, a lawful development certificate or a planning application gives you certainty before you build.

How long does a two-storey extension for a detached house take?

Allow 4 to 8 weeks for survey and design, then the approval period (councils should decide householder applications within 8 weeks of validation), then 4 to 8 weeks of technical design, which can overlap. The build itself usually takes 14 to 20 weeks, longer for large or complex designs.

Who handles building regulations for a project in Washwood Heath?

We handle it as part of the project. What's needed in England: building regulations approval (full plans recommended) from the council or a registered building control approver, with a completion certificate at the end. We prepare the drawings and the engineer's calculations, book the inspections and pass you the completion paperwork at the end.

How big an extension can a detached house take?

It depends on the plot, the boundaries and local design policy rather than a fixed limit. Under permitted development in England, extensions must not cover more than 50% of the land around the original house. With planning permission, the council judges size on proportion, neighbours and the character of the area.

Can I extend a detached house on both sides?

Sometimes. With planning permission, a council may accept extensions on both sides if the house stays well proportioned and keeps gaps to the boundaries. It is more common to extend on one side and the rear, or with a wraparound. We look at the plot as a whole before suggesting more than one extension.

Nearby

The same service in neighbouring towns:

Other extensions in Washwood Heath

All two-storey extension services in Washwood Heath · Two-storey extensions for detached houses across the West Midlands

Book a free site visit in Washwood Heath and we'll tell you what's possible, what approvals you need and what the design stage would cost.