House extensions in Sevenoaks
More space without moving: we plan and build extensions across Sevenoaks, with one team for the drawings, the council and the build.
- Postcode districtsTN13, TN14
- Price regionSouth East England (×1.12)
- Planning rulesEngland
- Site visitFree, no obligation
Areas we cover around Sevenoaks
Across TN13, TN14, we can visit, measure and advise. The same team covers Tonbridge (6 miles), Swanley (9 miles), Tunbridge Wells (10 miles), Dartford (12 miles), Gravesend (14 miles), all within easy reach. Just over the Greater London border, Orpington is about 8 miles away.
Planning rules in Sevenoaks
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).
Popular extension prices in Sevenoaks
Every figure below is a guide for Sevenoaks, adjusted for South East England build costs (×1.12) and including VAT. Design and council fees are shown separately on each page.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Side return extensions | 11 m² | £29,500 – £37,000 |
| Single-storey rear extensions | 20 m² | £45,500 – £58,500 |
| Conservatory replacement extensions | 14 m² | £33,500 – £43,500 |
| Orangery extensions | 16 m² | £50,000 – £63,000 |
| Extensions over a garage | 12 m² | £28,000 – £36,500 |
| Wraparound extensions | 25 m² | £64,000 – £81,500 |
| Double-storey extensions | 32 m² | £64,500 – £84,500 |
What works best for Sevenoaks houses?
In the South East, plenty of houses have already been extended once, which makes checking the remaining permitted development allowance an important early step.
Depending on the plot, orangery extensions and single-storey rear extensions are often the strongest options, with double-storey extensions worth considering where there is room.
Extension types and starting prices
- Glass box extensions · from £33,500
- Utility and boot room extensions · from £15,500
- Flat roof extensions · from £23,500
- Single-storey rear extensions · from £23,500
- Side extensions · from £24,500
- Conservatory replacement extensions · from £22,000
- Annexe extensions · from £61,500
- Side return extensions · from £20,000
- Bungalow extensions · from £29,000
- Extension plans and drawings · from £1,300
- Building regulations for extensions · from £1,000
- Planning permission for extensions · from £350
- Wraparound extensions · from £40,000
- Porch extensions · from £4,450
- Timber frame extensions · from £23,500
- Bedroom extensions · from £29,000
- Orangery extensions · from £33,500
- Pitched roof extensions · from £24,500
- Extensions over a garage · from £26,500
- Double-storey extensions · from £42,500
- Home office extensions · from £17,500
- Kitchen extensions · from £30,000
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
We confirm the build price in writing, based on the approved drawings and the finishes you have chosen.
Build and sign-off
The build is managed from start to finish, inspected at each stage and signed off on completion.
Questions about extensions in Sevenoaks
How much does an extension cost in Sevenoaks?
Using our South East England factor (×1.12), a standard-spec single-storey extension of 20 m² is a guide £45,500 to £58,500 including VAT, and a 32 m² two-storey extension £64,500 to £84,500. Your written price follows the survey.
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.
Do you handle building regulations?
Yes. We prepare the drawings and calculations, submit them and book inspections, ending with a completion certificate.
How long does an extension take in Sevenoaks?
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.
Book a free site visit in Sevenoaks
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.