Greater London
Rear extensions in Harlesden
We design and build rear extensions for homes in Harlesden, Greater London, from single-storey kitchen-diners across the back of the house to two-storey extensions that add a bedroom above.
Harlesden is in Greater London, with postcode districts including NW2, NW10 and W10. The nearest places we also cover are Willesden (0.8 miles) and Kensal Green (1.2 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 Harlesden
- 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 Greater London:
- 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 Harlesden
London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.
| Example | Guide inc VAT |
|---|---|
| Single-storey, 3 m × 4 m (12 m²) | £29,500–£48,500 |
| Single-storey, 4 m × 6 m (24 m²) | £59,500–£96,500 |
| Two-storey, 3 m × 5 m footprint (30 m²) | £70,000–£105,500 |
| Side return, about 14 m² | £42,000–£69,000 |
| Wraparound, about 25 m² | £71,500–£117,000 |
What are homes in Harlesden like to extend?
Period terraces in Harlesden sit alongside flats, and the difference matters: houses usually keep permitted development rights, while flats and maisonettes need planning permission for any rear extension.
Planning rules for Harlesden
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres within 2 metres of a boundary.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Every rear extension in England needs Building Regulations approval, whether or not planning is needed. You can use the council's building control service or a registered building control approver, by full plans (checked before work, usually within five weeks) or a building notice, and you get a completion certificate at the end.
Nearby towns
FAQ
Questions people ask
How much is a rear extension in Harlesden?
A 3 m × 4 m single-storey rear extension is about £29,500–£48,500 including VAT at our London guide rates; the written price follows a survey.
Do I need planning permission in Harlesden?
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 Harlesden 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.