Side extensions across Northamptonshire
A side extension in Northamptonshire starts with the right design and the right approval route. We take care of both, then build it with our own project management.
- Guide priceFrom £20,500 inc VAT
- PlanningSingle storey can be permitted development
- Towns covered9
- Site visitFree, no obligation
Towns in Northamptonshire
What is included
- Survey, design and street-view drawings
- Windows, doors and finishes to match
- Planning route checked or application made
- Structure, roof tied into the house
- New openings through the side wall
- Foundations near boundaries and any drains
Councils often prefer side extensions to sit slightly back from the front of the house with a lower roof, so the original building still reads clearly. We design to those principles from the start to avoid redesigns.
Guide prices for Northamptonshire
For Northamptonshire we adjust our national guide rates by ×0.95, the factor we use for East Midlands. Figures include VAT; your written quote after the survey replaces them.
Typical rates in Northamptonshire: £1,660 to £3,230 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 2.5 m × 5 m 12 m² | £20,500 – £25,500 | £23,000 – £30,500 | £29,500 – £39,000 |
| 3 m × 6 m 18 m² | £29,500 – £36,000 | £35,000 – £45,500 | £44,000 – £58,500 |
| 3 m × 8 m 24 m² | £39,500 – £48,000 | £46,500 – £60,500 | £59,000 – £78,000 |
For a figure based on your own dimensions, use our guide-price tool.
Planning rules that apply in Northamptonshire
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.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building over or within 3 m of a public sewer needs the water company's consent, usually through a build-over agreement, before the foundations go in.
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).
Working in Northamptonshire
Towns we cover in Northamptonshire include Northampton, Corby, Kettering, Wellingborough, Rushden, Daventry, Market Harborough, Towcester. 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.
What happens next
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
Drawings are prepared and agreed with you, then submitted for the right planning route and building regulations approval.
Fixed written price
You receive a written, itemised price and programme. Nothing starts until you are happy with it.
Build and sign-off
We build it with one project manager, book the building control inspections and hand over the completion certificate.
Common questions in Northamptonshire
Do I need building regulations approval in Northamptonshire?
Yes. Almost every extension needs it, whatever the planning route. We prepare the drawings and book the inspections.
Do you cover all of Northamptonshire?
Yes, across the whole of Northamptonshire. Site visits are free and there is no obligation.
Will my neighbours in Northamptonshire be involved?
If a planning application or prior approval is needed, the council notifies neighbours. If the work is on or near a shared boundary, party wall notices may also be needed.
How close to the boundary can I build?
It depends on height. In England, within 2 m of a boundary the eaves must not exceed 3 m under permitted development. Building on the boundary is possible but brings party wall and maintenance access issues we plan for.
Can I build over my driveway?
Yes, if the foundations work and you keep any parking the council requires. Drains and services under drives are common, so we check before design.
Book a free site visit in Northamptonshire
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.