Grantham, Lincolnshire
Single-storey rear extension in Grantham
Ground-floor space across the back of the house, usually for a kitchen, dining or family room. If you live in Grantham and want to know what a single-storey rear extension would cost and whether it needs planning, start with the online guide price or a free site visit.
Grantham is covered from our Lincolnshire round, including NG31. A single-storey rear extension in Grantham is mostly built from the garden side, so the house stays usable for most of the job.
Book a free site visit
Tell us about the house and we'll call to arrange a free, no-obligation visit.
How much does a single-storey rear extension cost in Grantham?
A single-storey rear extension in Grantham is priced at £1,840–£3,010 per square metre including VAT as a guide, before kitchen fit-out and fees. East Midlands prices sit a little below our West Midlands baseline.
| Size | Guide price inc VAT |
|---|---|
| 3 m wide × 4 m deep (12 m²) | £22,000–£36,000 |
| 4 m wide × 5 m deep (20 m²) | £37,000–£60,000 |
| 4 m wide × 6 m deep (24 m²) | £44,000–£72,000 |
We put a fixed price in writing once the design is agreed, and explain any provisional sums such as foundations.
Do you need planning permission for a single-storey rear extension in Grantham?
Here is how the rules in England apply to a single-storey rear extension in Grantham.
English permitted development (Class A) allows a single-storey rear extension of 3 metres on a terraced or semi-detached house and 4 metres on a detached one, measured from the original house, with a maximum height of 4 metres and eaves of no more than 3 metres within 2 metres of a boundary.
England also has the larger home extension route: a single-storey rear extension of up to 6 metres on an attached house or 8 metres on a detached house, after prior approval from the council. The council notifies your neighbours and has 42 days to decide; the fee is £249 (£310 for applications made from 8 December 2026). The route is not available on designated land such as conservation areas.
Conservation areas, National Parks, National Landscapes and the Broads restrict permitted development, and listed buildings always need listed building consent. We check your house's planning history and any conservation area before drawing, so the route is clear before you spend on plans.
What are homes in Grantham like to extend?
Grantham has plenty of inter-war semis and bungalows, and single-storey rear extensions suit both.
How a single-storey rear extension in Grantham comes together
Survey visit
We visit free of charge, measure up, check access, drainage and neighbours' extensions, and note what you want the room to do.
Drawings and budget
Floor plans and elevations for the options, each with a guide price.
Approvals
Permitted development check, prior approval or planning application, then Building Regulations drawings and structural calculations, plus party wall notices where they apply.
Fixed price and build
A written price for the agreed design, a start date and a named contact through the build, ending with the building control completion certificate.
Single-storey rear extensions near Grantham
Neighbouring places we cover include Sleaford (11.4 miles) and Newark on Trent (13.0 miles).
- Single-storey rear extension in Sleaford
- Single-storey rear extension in Newark on Trent
- Single-storey rear extension in Melton Mowbray
- Single-storey rear extension in Bourne
- Single-storey rear extension in Oakham
Other work in Grantham:
FAQ
Single-storey rear extension questions in Grantham
Can you match the brick or stone on my Grantham house?
We source the closest match and show you samples before ordering; reclaimed materials are often the best match on older houses.
Do you handle building control in Grantham?
Yes. We apply to the council or a registered building control approver and hand over the completion certificate.
Can I stay in the house during the build?
Usually yes. The noisiest, dustiest stage, removing the back wall, is kept to the final weeks and screened off. Most families set up a temporary kitchen elsewhere in the house.
How long does a rear extension take to build in Grantham?
Most single-storey rear extensions take 10 to 16 weeks on site and two-storey extensions 16 to 26 weeks, after design and approvals.
Will I need a structural engineer?
Yes for the beam over the new opening and usually the foundations; we arrange them and their calculations go to building control.
How much does a single-storey rear extension cost in Grantham?
As a guide, £1,840–£3,010 per square metre including VAT for a standard specification. For example, 3 m wide × 4 m deep (12 m²): about £22,000–£36,000 at that rate. Your written price follows the survey.