Northwood Hills, Greater London
Single-storey rear extension in Northwood Hills
Ground-floor space across the back of the house, usually for a kitchen, dining or family room. If you live in Northwood Hills and want to know what a single-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Northwood Hills and its postcode districts HA4, HA5 and HA6 are part of our Greater London coverage. A single-storey rear extension in Northwood Hills is mostly built from the garden side, so the house stays usable for most of the job.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a single-storey rear extension cost in Northwood Hills?
A single-storey rear extension in Northwood Hills is priced at £2,470–£4,030 per square metre including VAT as a guide, before kitchen fit-out and fees. London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £29,500–£48,500 |
| 4 m wide × 5 m deep (20 m²) | £49,500–£80,500 |
| 4 m wide × 6 m deep (24 m²) | £59,500–£96,500 |
Ground conditions, glazing, the roof and how far the house is opened up move the final figure within the range.
Do you need planning permission for a single-storey rear extension in Northwood Hills?
Whether your single-storey rear extension in Northwood Hills needs a planning application depends on its size, your house and any local restrictions.
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.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. At the first visit we measure what is there now and tell you which route fits: permitted development, prior approval or a planning application.
What are homes in Northwood Hills like to extend?
Much of Northwood Hills is 1920s and 1930s semis and short terraces with longer gardens than inner London, which suit full-width single-storey rear extensions. Parking suspensions, skip licences and controlled hours on residential streets shape the programme more than the build itself.
How a single-storey rear extension in Northwood Hills comes together
Free site visit
We measure the house and garden, look at the back wall, drainage and boundaries, and talk through what you want from the space.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Written price, then build
Once the design and approvals are in place, you get a fixed written price and programme, and we build through to sign-off.
Single-storey rear extensions near Northwood Hills
We also build single-storey rear extensions in nearby Northwood (1.1 miles) and Pinner (1.2 miles).
- Single-storey rear extension in Northwood
- Single-storey rear extension in Pinner
- Single-storey rear extension in Ruislip
- Single-storey rear extension in Ruislip Manor
- Single-storey rear extension in Ickenham
Other work in Northwood Hills:
FAQ
Single-storey rear extension questions in Northwood Hills
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
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.
Is a flat roof or a pitched roof better?
A warm flat roof keeps the extension low under first-floor windows and suits a roof lantern; a pitched or lean-to roof gives a vaulted ceiling. Both last for decades when built properly.
Can you match the brick or stone on my Northwood Hills house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Do you handle building control in Northwood Hills?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
What postcode areas do you cover around Northwood Hills?
Including HA4, HA5 and HA6, and the surrounding Greater London area.