Brentwood house extensions
More space without moving: we plan and build extensions across Brentwood, with one team for the drawings, the council and the build.
- Postcode districtsCM13, CM14, CM15
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Areas we cover around Brentwood
Postcode districts we cover around Brentwood include CM13, CM14, CM15. Nearby, we also take on projects in Billericay (5 miles), Basildon (7 miles), South Ockendon (8 miles), Stanford-le-Hope (9 miles), Wickford (9 miles). Just over the Greater London border, Hornchurch is about 6 miles away.
Choosing the right extension in Brentwood
The East of England mixes market-town terraces, inter-war semis and modern estates. Clay soils are common in parts of the region, which can affect foundation design.
Depending on the plot, wraparound extensions and single-storey rear extensions are often the strongest options, with double-storey extensions worth considering where there is room.
Brentwood extension prices at a glance
Prices on this page use our East of England factor of ×1.06, include VAT at 20% and cover the build; your written price follows a survey and agreed drawings.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Extensions over a garage | 12 m² | £26,500 – £34,500 |
| Orangery extensions | 16 m² | £47,000 – £59,500 |
| Single-storey rear extensions | 20 m² | £43,000 – £55,500 |
| Conservatory replacement extensions | 14 m² | £31,500 – £41,000 |
| Wraparound extensions | 25 m² | £60,500 – £77,000 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
Planning rules in Brentwood
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 extension can be permitted development if it is no more than 4 m high and no wider than half the width of the original house. Two-storey side extensions, and any side extension on designated land such as a conservation area, need a householder planning application.
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.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
All extension types we build in Brentwood
- Pitched roof extensions · from £23,500
- Annexe extensions · from £58,000
- Timber frame extensions · from £22,000
- Bungalow extensions · from £27,500
- Glass box extensions · from £31,500
- Bedroom extensions · from £27,500
- Kitchen extensions · from £28,500
- Extensions over a garage · from £25,000
- Building regulations for extensions · from £950
- Planning permission for extensions · from £350
- Double-storey extensions · from £40,000
- Side extensions · from £23,000
- Wraparound extensions · from £38,000
- Conservatory replacement extensions · from £21,000
- Utility and boot room extensions · from £14,500
- Home office extensions · from £16,500
- Side return extensions · from £19,000
- Single-storey rear extensions · from £22,000
- Extension plans and drawings · from £1,250
- Orangery extensions · from £31,500
- Flat roof extensions · from £22,000
- Porch extensions · from £4,200
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Brentwood
How much does an extension cost in Brentwood?
Using our East of England factor (×1.06), a standard-spec single-storey extension of 20 m² is a guide £43,000 to £55,500 including VAT, and a 32 m² two-storey extension £61,000 to £80,000. Your written price follows the survey.
How long does an extension take in Brentwood?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Who do I contract with?
Your contract is with S&K Property Investments and Improvement Ltd, which designs and manages the project and the build teams who carry it out.
Do you cover all of Brentwood?
Yes, including the surrounding parts of Essex. Site visits are free and there is no obligation.
Book a free site visit in Brentwood
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.