Stevenage house extensions
Looking to extend your home in Stevenage? Start here: extension types, guide prices for Stevenage, the planning rules that apply and how a project runs.
- Postcode districtsSG1, SG2, SG3, SG4
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Areas we cover around Stevenage
Across SG1, SG2, SG3, SG4, we can visit, measure and advise. Neighbouring towns we cover include Hitchin (5 miles), Letchworth Garden City (5 miles), Welwyn Garden City (7 miles), Harpenden (9 miles), Hertford (9 miles). Just over the Bedfordshire border, Luton is about 9 miles away.
What extensions cost in Stevenage
We publish guide prices so you can budget before anyone visits. For Stevenage they are adjusted by ×1.06, the factor we use across East of England.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Orangery extensions | 16 m² | £47,000 – £59,500 |
| Extensions over a garage | 12 m² | £26,500 – £34,500 |
| Wraparound extensions | 25 m² | £60,500 – £77,000 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
| Single-storey rear extensions | 20 m² | £43,000 – £55,500 |
Approvals for an extension in Stevenage
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.
If the work involves a shared wall, building on the boundary, or digging foundations within 3 m (sometimes 6 m) of a neighbour's building, the Party Wall etc. Act 1996 applies and notice must be served before work starts: two months for work to a party wall, one month for new walls on the boundary and for excavations.
Applications are decided by the local planning authority (your district, borough or unitary council).
Choosing the right extension in Stevenage
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
Start by comparing wraparound extensions, single-storey rear extensions and bungalow extensions: between them they cover most of the layouts we see requested for houses like these.
Every extension type in Stevenage
- Glass box extensions · from £31,500
- Extensions over a garage · from £25,000
- Timber frame extensions · from £22,000
- Kitchen extensions · from £28,500
- Side return extensions · from £19,000
- Bungalow extensions · from £27,500
- Annexe extensions · from £58,000
- Extension plans and drawings · from £1,250
- Bedroom extensions · from £27,500
- Planning permission for extensions · from £350
- Pitched roof extensions · from £23,500
- Utility and boot room extensions · from £14,500
- Conservatory replacement extensions · from £21,000
- Orangery extensions · from £31,500
- Building regulations for extensions · from £950
- Wraparound extensions · from £38,000
- Single-storey rear extensions · from £22,000
- Porch extensions · from £4,200
- Double-storey extensions · from £40,000
- Side extensions · from £23,000
- Home office extensions · from £16,500
- Flat roof extensions · from £22,000
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
Build and sign-off
Our team builds the extension, keeps you updated weekly and finishes with building control sign-off.
Questions about extensions in Stevenage
How much does an extension cost in Stevenage?
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.
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.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Stevenage, and the guide-price tool gives a range for your own size and finish in about a minute.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Book a free site visit in Stevenage
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.