Extensions in Farnham: design, planning and build
Planning an extension in Farnham? Compare extension types, see guide prices adjusted for Farnham and book a free site visit.
- Postcode districtsGU9, GU10
- Price regionSouth East England (×1.12)
- Planning rulesEngland
- Site visitFree, no obligation
Popular extension prices in Farnham
Use these Farnham 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) |
|---|---|---|
| Double-storey extensions | 32 m² | £64,500 – £84,500 |
| Side return extensions | 11 m² | £29,500 – £37,000 |
| Extensions over a garage | 12 m² | £28,000 – £36,500 |
| Single-storey rear extensions | 20 m² | £45,500 – £58,500 |
| Kitchen extensions | 20 m² | £47,000 – £59,500 |
| Orangery extensions | 16 m² | £50,000 – £63,000 |
| Conservatory replacement extensions | 14 m² | £33,500 – £43,500 |
Areas we cover around Farnham
Postcode districts we cover around Farnham include GU9, GU10. The same team covers Godalming (8 miles), Camberley (9 miles), Guildford (10 miles), Woking (13 miles), Weybridge (18 miles), all within easy reach. Aldershot, in Hampshire, is roughly 3 miles from Farnham and also on our list.
What works best for Farnham 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.
For many houses here, double-storey extensions, wraparound extensions or orangery extensions gives the most useful space for the budget.
Planning and building control in Farnham
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 two-storey rear extension is permitted development only if it projects no more than 3 m from the original rear wall, sits at least 7 m from the rear boundary, matches the roof pitch and uses obscure, non-opening side windows upstairs. Most two-storey extensions therefore go through a householder planning application, which costs £548 from 1 April 2026 and normally takes about 8 weeks.
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).
Extension types and starting prices
- Utility and boot room extensions · from £15,500
- Flat roof extensions · from £23,500
- Timber frame extensions · from £23,500
- Bedroom extensions · from £29,000
- Side return extensions · from £20,000
- Conservatory replacement extensions · from £22,000
- Single-storey rear extensions · from £23,500
- Orangery extensions · from £33,500
- Pitched roof extensions · from £24,500
- Bungalow extensions · from £29,000
- Kitchen extensions · from £30,000
- Glass box extensions · from £33,500
- Double-storey extensions · from £42,500
- Home office extensions · from £17,500
- Extensions over a garage · from £26,500
- Porch extensions · from £4,450
- Annexe extensions · from £61,500
- Side extensions · from £24,500
- Planning permission for extensions · from £350
- Wraparound extensions · from £40,000
- Building regulations for extensions · from £1,000
- Extension plans and drawings · from £1,300
Free site visit
A designer visits, takes measurements and photos, and discusses layouts, budget and timing with you.
Design and approvals
We produce the drawings and structural design, and manage the approvals so they are in place before work starts.
Fixed written price
With the design and specification agreed, you get a fixed written price and a start date.
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 Farnham
How much does an extension cost in Farnham?
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.
How long does an extension take in Farnham?
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.
Can I get a price before anyone visits?
Yes. This page shows guide prices adjusted for Farnham, and the guide-price tool gives a range for your own size and finish in about a minute.
Book a free site visit in Farnham
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.