Chelmsford, Essex
Two-storey rear extension in Chelmsford
Two-storey rear extension in Chelmsford: a larger kitchen downstairs and an extra bedroom or bathroom upstairs, under one roof. We measure the house, show you what the rules allow, price it in writing and build it.
Chelmsford sits in Essex, with postcode districts including CM1. In Essex we check the neighbours' rear windows first, because the upper floor is where most two-storey schemes win or lose planning.
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 Chelmsford?
For Chelmsford we work from the East of England rate: £1,910–£2,860 per square metre of new floor, including VAT, standard specification. East of England prices run slightly above our West Midlands baseline; clay soils near trees are the main foundation variable.
| Size | Guide price inc VAT |
|---|---|
| 3 m × 5 m footprint, two floors (30 m²) | £57,000–£86,000 |
| 4 m × 6 m footprint, two floors (48 m²) | £91,500–£137,500 |
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 two-storey rear extension in Chelmsford?
Planning for a two-storey rear extension in Chelmsford follows the English householder rules.
A two-storey rear extension can be permitted development in England only if it projects no more than 3 metres, stays at least 7 metres from the rear boundary, matches the existing roof pitch and has obscure-glazed upper side windows. In practice most double-storey rear extensions go through a householder planning application.
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 Chelmsford like to extend?
Chelmsford mixes Victorian terraces with 1930s semis, so both side returns and full-width kitchen extensions suit houses here.
How a two-storey rear extension in Chelmsford comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Options and costs
We draw layout options and price each one, so the budget shapes the design rather than surprising you later.
Planning and regulations
We take the design through the right planning route, then produce the construction drawings and engineer's calculations for building control.
Build and sign-off
We build to the approved drawings with regular updates, then hand over the building control completion certificate and any guarantees from suppliers.
Two-storey rear extensions near Chelmsford
Close by, we work in Billericay, about 7.7 miles away, and Witham, about 8.5 miles away.
- Two-storey rear extension in Billericay
- Two-storey rear extension in Witham
- Two-storey rear extension in Maldon
- Two-storey rear extension in Wickford
- Two-storey rear extension in Braintree
Other work in Chelmsford:
FAQ
Two-storey rear extension questions in Chelmsford
Is the site visit in Chelmsford free?
Yes. We visit, measure up and talk through the options with no cost and no obligation.
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.
What is the 45-degree rule?
Many councils check that a two-storey extension does not cross a 45-degree line drawn from the nearest habitable window of the neighbouring house. We test it at the first drawing.
How long does a rear extension take to build in Chelmsford?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
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 you handle building control in Chelmsford?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.