House extensions in Northampton
Every type of house extension in Northampton, from single-storey kitchen extensions to two-storey additions, side returns and orangeries. We design, handle the approvals and build.
- Postcode districtsNN1, NN2, NN3, NN4, NN5, NN7
- Price regionEast Midlands (×0.95)
- Planning rulesEngland
- Site visitFree, no obligation
Guide prices for Northampton
Use these Northampton guide prices to sense-check a budget; the guide-price tool narrows them to your own size, and the site visit turns them into a written figure.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Orangery extensions | 16 m² | £42,500 – £53,500 |
| Side return extensions | 11 m² | £25,000 – £31,500 |
| Wraparound extensions | 25 m² | £54,500 – £69,000 |
| Extensions over a garage | 12 m² | £23,500 – £31,000 |
| Conservatory replacement extensions | 14 m² | £28,500 – £37,000 |
Where we work near Northampton
Across NN1, NN2, NN3, NN4, NN5, NN7, we can visit, measure and advise. We also work in nearby Wellingborough (9 miles), Towcester (10 miles), Daventry (12 miles), Rushden (12 miles), Kettering (12 miles). Just over the Buckinghamshire border, Milton Keynes is about 15 miles away.
Choosing the right extension in Northampton
The East Midlands has plenty of inter-war and post-war semis and detached houses with room to extend, alongside Victorian terraces in the towns.
Depending on the plot, single-storey rear extensions and side extensions are often the strongest options, with conservatory replacement extensions worth considering where there is room.
Do extensions in Northampton need planning permission?
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.
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).
Every extension type in Northampton
- Conservatory replacement extensions · from £19,000
- Utility and boot room extensions · from £13,000
- Building regulations for extensions · from £850
- Annexe extensions · from £52,000
- Planning permission for extensions · from £300
- Glass box extensions · from £28,500
- Extensions over a garage · from £22,500
- Wraparound extensions · from £34,000
- Home office extensions · from £15,000
- Timber frame extensions · from £19,500
- Double-storey extensions · from £36,000
- Orangery extensions · from £28,500
- Porch extensions · from £3,800
- Side extensions · from £20,500
- Pitched roof extensions · from £21,000
- Single-storey rear extensions · from £19,500
- Bedroom extensions · from £24,500
- Bungalow extensions · from £24,500
- Kitchen extensions · from £25,500
- Side return extensions · from £17,000
- Extension plans and drawings · from £1,100
- Flat roof extensions · from £19,500
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
We draw the design, agree it with you and handle planning or permitted development checks and building regulations.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
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 Northampton
How much does an extension cost in Northampton?
Using our East Midlands factor (×0.95), a standard-spec single-storey extension of 20 m² is a guide £38,500 to £49,500 including VAT, and a 32 m² two-storey extension £54,500 to £71,500. Your written price follows the survey.
Do I need planning permission for an extension in Northampton?
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.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
Will my neighbours need to be told?
If you apply for planning or prior approval the council notifies them, and in England party wall notices may be needed for work near a shared boundary.
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 Northampton
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.