Semi-detached rear extension in Northwood Hills

How much does a semi-detached rear extension cost in Northwood Hills?

For Northwood Hills we work from the London rate: £2,470–£4,030 per square metre of new floor, including VAT, standard specification. London prices sit at the top of our range because of labour rates, access through the house, parking suspensions and skip licences.

Your written price follows a measured survey and an agreed design, so it reflects your house, not an average.

Do you need planning permission for a semi-detached rear extension in Northwood Hills?

Planning for a semi-detached rear extension in Northwood Hills follows the English householder rules.

In England a single-storey rear extension can often be built under permitted development: up to 3 metres beyond the original rear wall of an attached house, or 4 metres on a detached house, no higher than 4 metres, with eaves no higher than 3 metres if any part is within 2 metres of a boundary.

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.

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 semi-detached rear extension in Northwood Hills comes together

1. Survey visit

   We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.

2. Options and costs

   We draw layout options and price each one, so the budget shapes the design rather than surprising you later.

3. Paperwork handled

   Planning, prior approval or permitted development, Building Regulations approval, structural design and party wall notices are all handled by us.

4. 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.

Semi-detached rear extensions near Northwood Hills

Close by, we work in Northwood, about 1.1 miles away, and Pinner, about 1.2 miles away.

• Semi-detached rear extension in Northwood
• Semi-detached rear extension in Pinner
• Semi-detached rear extension in Ruislip
• Semi-detached rear extension in Ruislip Manor
• Semi-detached rear extension in Ickenham

Other work in Northwood Hills:

• Single-storey rear extension
• Two-storey rear extension
• Kitchen-diner rear extension
• Side return extension
• Wraparound extension
• Glazed rear extension

All rear extensions in Northwood Hills