Gainsborough house extensions
More space without moving: we plan and build extensions across Gainsborough, with one team for the drawings, the council and the build.
- Postcode districtsDN21
- Price regionEast Midlands (×0.95)
- Planning rulesEngland
- Site visitFree, no obligation

Planning rules in Gainsborough
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).
Guide prices for Gainsborough
Use these Gainsborough 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) |
|---|---|---|
| Wraparound extensions | 25 m² | £54,500 – £69,000 |
| Kitchen extensions | 20 m² | £39,500 – £50,500 |
| Double-storey extensions | 32 m² | £54,500 – £71,500 |
| Orangery extensions | 16 m² | £42,500 – £53,500 |
| Extensions over a garage | 12 m² | £23,500 – £31,000 |
| Single-storey rear extensions | 20 m² | £38,500 – £49,500 |
| Conservatory replacement extensions | 14 m² | £28,500 – £37,000 |
Covering Gainsborough and nearby
Site visits are available across Gainsborough (DN21). The same team covers Scunthorpe (14 miles), Lincoln (14 miles), Grimsby (31 miles), Cleethorpes (33 miles), Grantham (33 miles), all within easy reach. Retford, in Nottinghamshire, is roughly 8 miles from Gainsborough and also on our list.
What works best for Gainsborough houses?
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.
The types we would usually look at first for a home in Gainsborough are side extensions, double-storey extensions and conservatory replacement extensions, depending on the garden and how the house is laid out.
Every extension type in Gainsborough
- Timber frame extensions · from £19,500
- Bungalow extensions · from £24,500
- Flat roof extensions · from £19,500
- Porch extensions · from £3,800
- Building regulations for extensions · from £850
- Planning permission for extensions · from £300
- Annexe extensions · from £52,000
- Side extensions · from £20,500
- Extension plans and drawings · from £1,100
- Bedroom extensions · from £24,500
- Home office extensions · from £15,000
- Glass box extensions · from £28,500
- Kitchen extensions · from £25,500
- Extensions over a garage · from £22,500
- Utility and boot room extensions · from £13,000
- Wraparound extensions · from £34,000
- Single-storey rear extensions · from £19,500
- Pitched roof extensions · from £21,000
- Conservatory replacement extensions · from £19,000
- Side return extensions · from £17,000
- Orangery extensions · from £28,500
- Double-storey extensions · from £36,000
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
Design and approvals
Once the layout is agreed, we deal with the council: planning permission or written confirmation that none is needed, plus building control.
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 Gainsborough
How much does an extension cost in Gainsborough?
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.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Gainsborough, and the guide-price tool gives a range for your own size and finish in about a minute.
How long does an extension take in Gainsborough?
Usually 2 to 4 months of design and approvals, then 10 to 16 weeks on site for a single-storey extension or 16 to 24 weeks for two storeys.
Do I need planning permission for an extension in Gainsborough?
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.
Book a free site visit in Gainsborough
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.