House extensions in Willesden
Planning an extension in Willesden? Compare extension types, see guide prices adjusted for Willesden and book a free site visit.
- Postcode districtsNW2, NW6, NW10, W9, W10, W12
- Price regionLondon (×1.3)
- Planning rulesEngland
- Site visitFree, no obligation
Do extensions in Willesden need planning permission?
In England a single-storey rear extension can usually go up to 3 m beyond the original rear wall of a semi-detached or terraced house, or 4 m on a detached house, without a planning application, provided it is no more than 4 m high, keeps eaves to 3 m within 2 m of a boundary and, with other buildings, covers no more than half the land around the original house. The larger home extension prior approval scheme raises those depths to 6 m and 8 m, with neighbours notified and a 42-day decision.
In England a single-storey side return infill is often permitted development if it stays within the height limits and is no wider than half the width of the original house. Conservation areas, listed buildings and flats always need an application, and the boundary wall usually brings in the Party Wall Act.
In a conservation area, national park, National Landscape, the Broads or a World Heritage Site the permitted development limits are tighter (no side or two-storey extensions without an application). Listed homes need listed building consent, and if permitted development rights have been removed, any extension needs an application.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Covering Willesden and nearby
Postcode districts we cover around Willesden include NW2, NW6, NW10, W9, W10, W12. Neighbouring towns we cover include Harlesden (1 mile), Cricklewood (2 miles), Notting Hill (2 miles), Shepherds Bush (2 miles), Kilburn (2 miles). For homes towards Hertfordshire, Borehamwood is around 9 miles away.
What extensions cost in Willesden
We publish guide prices so you can budget before anyone visits. For Willesden they are adjusted by ×1.3, the factor we use across London.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Wraparound extensions | 25 m² | £74,500 – £94,500 |
| Conservatory replacement extensions | 14 m² | £39,000 – £50,500 |
| Side return extensions | 11 m² | £34,000 – £43,000 |
| Kitchen extensions | 20 m² | £54,500 – £69,000 |
| Double-storey extensions | 32 m² | £74,500 – £98,000 |
| Extensions over a garage | 12 m² | £32,500 – £42,500 |
What works best for Willesden houses?
London's housing is dominated by Victorian and Edwardian terraces, many with a rear outrigger and a side return, and 1930s semis in the outer boroughs. Conservation areas are common, so the planning check comes first.
Depending on the plot, glass box extensions and wraparound extensions are often the strongest options, with side return extensions worth considering where there is room.
Choose an extension type
- Annexe extensions · from £71,500
- Orangery extensions · from £39,000
- Timber frame extensions · from £27,000
- Bungalow extensions · from £34,000
- Glass box extensions · from £39,000
- Wraparound extensions · from £46,500
- Planning permission for extensions · from £450
- Side extensions · from £28,500
- Side return extensions · from £23,000
- Pitched roof extensions · from £28,500
- Flat roof extensions · from £27,000
- Extensions over a garage · from £31,000
- Building regulations for extensions · from £1,150
- Conservatory replacement extensions · from £26,000
- Bedroom extensions · from £33,500
- Home office extensions · from £20,500
- Porch extensions · from £5,200
- Single-storey rear extensions · from £27,000
- Utility and boot room extensions · from £18,000
- Double-storey extensions · from £49,000
- Extension plans and drawings · from £1,550
- Kitchen extensions · from £35,000
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Willesden
How much does an extension cost in Willesden?
Using our London factor (×1.3), a standard-spec single-storey extension of 20 m² is a guide £53,000 to £68,000 including VAT, and a 32 m² two-storey extension £74,500 to £98,000. Your written price follows the survey.
Do you cover all of Willesden?
Yes, including the surrounding parts of Greater London. Site visits are free and there is no obligation.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Will my neighbours need to be told?
If you apply for planning or prior approval the council notifies them, and in England party wall notices may be needed for work near a shared boundary.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Willesden, and the guide-price tool gives a range for your own size and finish in about a minute.
Book a free site visit in Willesden
We will measure up, check the planning position and give you honest guide figures.
- Free, no-obligation site visit
- Planning route checked before you spend on drawings
- Written price once the design is agreed
- Building control sign-off at the end
Prefer to talk? Call 0800 088 6341 or .
Book a free site visit
Tell us a little about the project and we will arrange a time.