West Midlands
Rear extensions in Knowle
From the first measured visit to building control sign-off, we handle rear extensions in Knowle under one contract.
Knowle is in the West Midlands, with postcode districts including B40. The nearest places we also cover are Solihull (2.9 miles) and Shirley (4.1 miles).
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
Rear extensions we build in Knowle
- Single-storey rear extensions
- Two-storey rear extensions
- Kitchen-diner rear extensions
- Side return extensions
- Wraparound extensions
- Glazed and glass-box rear extensions
- Rear extensions for terraced houses
- Rear extensions for semi-detached houses
- Rear extensions for bungalows
- Rear extension plans and planning applications
Also available across the West Midlands:
- Rear extensions for detached houses
- Flat-roof rear extensions
- Pitched and lean-to roof rear extensions
- Knocking through to a rear extension
- Roof lanterns and rooflights for rear extensions
- Permitted development rear extensions
- Larger home extension prior approval (England)
- Building Regulations for rear extensions
Rear extension prices in Knowle
The West Midlands is the baseline for our guide prices.
| Example | Guide inc VAT |
|---|---|
| Single-storey, 3 m × 4 m (12 m²) | £23,000–£37,000 |
| Single-storey, 4 m × 6 m (24 m²) | £45,500–£74,500 |
| Two-storey, 3 m × 5 m footprint (30 m²) | £54,000–£81,000 |
| Side return, about 14 m² | £32,000–£53,000 |
| Wraparound, about 25 m² | £55,000–£90,000 |
What are homes in Knowle like to extend?
Knowle has a lot of post-war semis and estate houses with long gardens and side access, which makes rear extensions quicker to build.
Planning rules for Knowle
Under England's householder permitted development rules you can usually add 3 metres at the back of an attached house, or 4 metres on a detached house, without a planning application, as long as the extension stays under 4 metres high and its eaves stay under 3 metres where it is within 2 metres of a boundary.
If 3 or 4 metres is not enough, England's prior approval route allows 6 metres on a terraced or semi-detached house and 8 metres on a detached house for a single-storey rear extension. Neighbours are consulted, the council decides within 42 days, and the fee is £249, rising to £310 from 8 December 2026.
Planning and Building Regulations are separate in England: even a permitted development extension is inspected for foundations, drainage, structure, insulation, fire safety and ventilation, through the council or a registered building control approver, ending with a completion certificate.
Nearby towns
FAQ
Questions people ask
How much is a rear extension in Knowle?
A 3 m × 4 m single-storey rear extension is about £23,000–£37,000 including VAT at our West Midlands guide rates; the written price follows a survey.
Do I need planning permission in Knowle?
Often not for a single-storey rear extension of up to 3 metres (4 metres on a detached house) under permitted development, or up to 6 or 8 metres with prior approval, unless the house is in a conservation area or its rights have been removed.
Is the site visit in Knowle free?
Yes, with no obligation.
Do I need a party wall agreement?
In England, usually yes if the extension is on or near a shared boundary or the foundations are close to a neighbour's building. We serve the notices.