House extensions in Corby
Single and double storey extensions in Corby, with the planning route and building control sorted first.
A single storey extension in Corby typically costs £2,400–£3,200 per m² finished ready for decoration, roughly £29,000–£38,500 for a 12m² rear extension, with any kitchen fit-out priced separately. Building control in Corby is North Northamptonshire Council building control: quoted by the council for each job.
- Typical cost
- £2,400–£3,200 per m²
- Building control
- Council building control: free quote per job
- Planning advice
- North Northamptonshire Council: £187
- Time on site
- Several weeks
Our 2026 guide prices, all in. Your fixed price comes in writing after the site visit. Council fees checked October 2026.
What house extensions in Corby usually involve
Extending is the most cost-effective way to add space and value without the upheaval of moving. We design and build single and double storey extensions, kitchen and dining extensions and rear and side returns across Corby and the surrounding Northamptonshire villages — matched to the town's many modern brick homes as well as older village properties. Every build meets Building Regulations and is signed off through Local Authority Building Control, with the planning or permitted-development route confirmed before we start.
The extensions Corby homes ask for most
Corby has a large amount of post-war and modern housing alongside older village homes, and the right extension depends on the property.
Modern and estate homes across Corby frequently allow rear and side extensions under permitted development, which avoids a full planning application. We confirm the route at the first visit so there are no surprises.
Kitchen and rear-return extensions are the most popular here — opening a standard kitchen into a bright open-plan family space. This often means removing a load-bearing wall and installing a steel beam to a structural engineer's calculations, which we carry out as standard.
Village and period properties around Corby — in Weldon, Gretton and Cottingham — need more sympathetic detailing and matched materials, and where a conservation area applies we prepare the work to the standard expected.
What Building Regulations cover
Every extension must meet Building Regulations regardless of planning: foundations sized for the ground, a damp proof course tied into the existing wall, insulation to current standards, structural support over openings, fire safety, ventilation and drainage. We build to those standards and arrange Building Control inspections at foundations, damp proofing, structure and completion — so you receive the completion certificate a buyer's solicitor will later want.
Corby & villages we cover
We cover Corby and the surrounding villages including Weldon, Gretton, Cottingham, Middleton, Rockingham and Stanion.
Design & approvals
We help with drawings, structural calculations, the planning or permitted-development route and the Building Control application.
Build & structure
Foundations, matched brickwork, steel beams, roofing and weathering — inspected at each stage.
Thinking about extending in Corby?
We will visit, talk through what's possible, check the planning position and quote in writing — all free and without pressure.
Ground, drainage and conservation in Corby
Corby sits on the Northampton Sand ironstone that fed the steelworks, and large areas around the town were opencast quarried and restored. Ground can change from natural ironstone to clay or fill within a garden, so we dig before we design the base and drainage.
Corby has nine conservation areas, including the Old Village, Cottingham and Middleton, Gretton, Rockingham, Stanion, Great Oakley and Weldon. Its only Article 4 direction (Kingswood) controls houses in multiple occupation and does not affect driveways, porches or extensions.
The Willow Brook runs through Corby and Weldon, with an Environment Agency flood storage reservoir at Weldon, so properties near the brook need drainage planned with care. You can check any address on the Environment Agency flood map.
Sources: North Northamptonshire conservation areas · Priors Hall Park.
Permissions and fees in Corby
- Planning routeMany single storey rear extensions are permitted development; a householder application costs £548 and a lawful development certificate £274 (national fees from April 2026). Planning Portal guidance
- Pre-application adviceIf anything is unclear, North Northamptonshire Council gives householder pre-application advice for £187. Pre-application advice
- Building regulationsNorth Northamptonshire Council building control: quoted by the council for each job. Building control fees
- Sewers and neighboursIf a public sewer runs within 3m, you need a build-over agreement with Anglian Water. Anglian Water: building over or near sewers
- BuildOne fixed written price, then the build, inspections and the completion certificate.
Council fees and rules checked October 2026. Planning fees are the national fees from 1 April 2026.
What you get
- Planning or permitted development route confirmed before anything starts
- Structural calculations and building regulations drawings arranged
- Stone or brick matched to the house
- Build-over agreements with Anglian Water where a sewer runs close
The specification
- Drawings, calculations and approvals
- Foundations inspected by building control
- Blockwork, insulation and the outer skin in matching stone or brick
- Roof, windows and doors
- First and second fix, plastering
- Completion certificate from building control
Rated 5.0 from 37 Google reviews
“Excellent Porch Extension by Lewis and the Team We recently had a porch extension completed by Lewis and his team, and we are extremely pleased with the result. From start to finish, Lewis was professional, reliable, and easy to communicate with. …”
Deepak · Porch extension — Google review
“These guys fitted our job in at short notice, did a great job despite the harsh weather. We had great communication throughout the project as it was not quite as simple as we first thought. We definitely recommend them and will be using them for future projects”
John — Google review
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House extensions in Corby: questions
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Can you match the existing brick?
How much does a house extension cost in Corby?
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Who handles building control in Corby?
Request a site visit in Corby
We measure up, check levels and drainage, and send a written proposal with the build-up, the programme and one whole price. No pressure and no follow-up sales calls.