House extensions in Cambridge
Every type of house extension in Cambridge, from single-storey kitchen extensions to two-storey additions, side returns and orangeries. We design, handle the approvals and build.
- Postcode districtsCB1, CB2, CB3, CB4, CB5, CB22
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Planning and building control in Cambridge
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 two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
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).
Which extension suits a Cambridge home?
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, bungalow extensions and single-storey rear extensions are often the strongest options, with wraparound extensions worth considering where there is room.
Areas we cover around Cambridge
Postcode districts we cover around Cambridge include CB1, CB2, CB3, CB4, CB5, CB22. We also work in nearby Ely (15 miles), Huntingdon (16 miles), St Neots (16 miles), March (24 miles), Peterborough (30 miles). For homes towards Suffolk, Newmarket is around 13 miles away.
What extensions cost in Cambridge
We publish guide prices so you can budget before anyone visits. For Cambridge they are adjusted by ×1.06, the factor we use across East of England.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Kitchen extensions | 20 m² | £44,500 – £56,500 |
| Wraparound extensions | 25 m² | £60,500 – £77,000 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
| Extensions over a garage | 12 m² | £26,500 – £34,500 |
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
| Single-storey rear extensions | 20 m² | £43,000 – £55,500 |
| Orangery extensions | 16 m² | £47,000 – £59,500 |
Extension types and starting prices
- Extensions over a garage · from £25,000
- Porch extensions · from £4,200
- Building regulations for extensions · from £950
- Bungalow extensions · from £27,500
- Home office extensions · from £16,500
- Flat roof extensions · from £22,000
- Side return extensions · from £19,000
- Pitched roof extensions · from £23,500
- Conservatory replacement extensions · from £21,000
- Wraparound extensions · from £38,000
- Side extensions · from £23,000
- Double-storey extensions · from £40,000
- Extension plans and drawings · from £1,250
- Single-storey rear extensions · from £22,000
- Utility and boot room extensions · from £14,500
- Kitchen extensions · from £28,500
- Annexe extensions · from £58,000
- Bedroom extensions · from £27,500
- Orangery extensions · from £31,500
- Timber frame extensions · from £22,000
- Planning permission for extensions · from £350
- Glass box extensions · from £31,500
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Work is carried out to the agreed programme, inspected by building control and signed off at the end.
Questions about extensions in Cambridge
How much does an extension cost in Cambridge?
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.
Do I need planning permission for an extension in Cambridge?
Not always. It depends on the size, position and your property's history. Many single-storey rear extensions in England are permitted development or can use prior approval.
How long does an extension take in Cambridge?
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.
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.
Book a free site visit in Cambridge
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.