Northwood Hills, Greater London
Two-storey rear extension in Northwood Hills
A larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. If you live in Northwood Hills and want to know what a two-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. Two-storey rear extensions suit semi-detached houses in Northwood Hills best, where the extra bedroom matters as much as the bigger kitchen.
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 two-storey rear extension cost in Northwood Hills?
In Northwood Hills, our guide for a two-storey rear extension is £2,340–£3,510 per square metre including VAT for a standard specification. 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 × 5 m footprint, two floors (30 m²) | £70,000–£105,500 |
| 4 m × 6 m footprint, two floors (48 m²) | £112,500–£168,500 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a two-storey rear extension in Northwood Hills?
Planning for a two-storey rear extension in Northwood Hills follows the English householder rules.
England's rules allow a rear extension of more than one storey without an application only when it is no deeper than 3 metres and at least 7 metres from the boundary opposite the rear wall, and never on designated land. Most two-storey schemes need householder planning permission.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. Before any drawing we look up the property's history with the council, because earlier extensions and removed rights change the answer.
What are homes in Northwood Hills like to extend?
Northwood Hills is mostly 1930s semis, short terraces and post-war houses, so full-width single-storey and two-storey rear extensions are realistic on many plots. Some later estates had permitted development rights removed by condition, so we check the planning history first.
How a two-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.
Design and guide price
Two or three layout options with a guide price for each, so you choose the design knowing what it costs.
Paperwork handled
Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.
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.
Two-storey rear extensions near Northwood Hills
Close by, we work in Northwood, about 1.1 miles away, and Pinner, about 1.2 miles away.
- Two-storey rear extension in Northwood
- Two-storey rear extension in Pinner
- Two-storey rear extension in Ruislip
- Two-storey rear extension in Ruislip Manor
- Two-storey rear extension in Ickenham
Other work in Northwood Hills:
FAQ
Two-storey rear extension questions in Northwood Hills
What postcode areas do you cover around Northwood Hills?
Including HA4, HA5 and HA6, and the surrounding Greater London area.
How long does a rear extension take to build in Northwood Hills?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Does a two-storey rear extension need planning permission?
Almost always. England and Northern Ireland allow 3 metres without an application only if at least 7 metres remains to the rear boundary; Wales and Scotland are similar or stricter.
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.
Can I live at home while the extension is built?
Usually yes. Most of the work is outside until the back wall is opened near the end, and that stage is screened off.
Can I get a price without a visit?
Our online guide-price tool gives a range in a couple of minutes. A written price needs a survey.