Rickmansworth house extensions
We design and build house extensions for homes in Rickmansworth and the surrounding Hertfordshire area, with guide prices adjusted for the region.
- Postcode districtsWD3
- Price regionEast of England (×1.06)
- Planning rulesEngland
- Site visitFree, no obligation
Covering Rickmansworth and nearby
Our survey diary covers Rickmansworth, including WD3. Neighbouring towns we cover include Watford (4 miles), Bushey (5 miles), Hemel Hempstead (8 miles), Borehamwood (9 miles), Berkhamsted (9 miles). Just over the Buckinghamshire border, Chalfont St Peter is about 4 miles away.
Approvals for an extension in Rickmansworth
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).
Popular extension prices in Rickmansworth
Every figure below is a guide for Rickmansworth, adjusted for East of England build costs (×1.06) and including VAT. Design and council fees are shown separately on each page.
| Extension type | Example size | Standard spec (inc VAT) |
|---|---|---|
| Double-storey extensions | 32 m² | £61,000 – £80,000 |
| Conservatory replacement extensions | 14 m² | £31,500 – £41,000 |
| Kitchen extensions | 20 m² | £44,500 – £56,500 |
| Orangery extensions | 16 m² | £47,000 – £59,500 |
| Wraparound extensions | 25 m² | £60,500 – £77,000 |
| Extensions over a garage | 12 m² | £26,500 – £34,500 |
| Side return extensions | 11 m² | £27,500 – £35,000 |
Which extension suits a Rickmansworth home?
Across the East of England many houses sit on generous plots, and single-storey and wraparound extensions are a natural fit.
For many houses here, single-storey rear extensions, wraparound extensions or bungalow extensions gives the most useful space for the budget.
Extension types and starting prices
- Pitched roof extensions · from £23,500
- Double-storey extensions · from £40,000
- Bungalow extensions · from £27,500
- Annexe extensions · from £58,000
- Side return extensions · from £19,000
- Orangery extensions · from £31,500
- Utility and boot room extensions · from £14,500
- Home office extensions · from £16,500
- Extension plans and drawings · from £1,250
- Porch extensions · from £4,200
- Kitchen extensions · from £28,500
- Glass box extensions · from £31,500
- Single-storey rear extensions · from £22,000
- Flat roof extensions · from £22,000
- Wraparound extensions · from £38,000
- Extensions over a garage · from £25,000
- Timber frame extensions · from £22,000
- Side extensions · from £23,000
- Bedroom extensions · from £27,500
- Planning permission for extensions · from £350
- Conservatory replacement extensions · from £21,000
- Building regulations for extensions · from £950
Free site visit
First, a site visit: we look at the house, garden, access and drains and listen to what you need.
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
The price is fixed in writing once the design is settled, with a clear programme and payment stages.
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 Rickmansworth
How much does an extension cost in Rickmansworth?
Using our East of England factor (×1.06), a standard-spec single-storey extension of 20 m² is a guide £43,000 to £55,500 including VAT, and a 32 m² two-storey extension £61,000 to £80,000. Your written price follows the survey.
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.
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.
Do I need planning permission for an extension in Rickmansworth?
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.
How long does an extension take in Rickmansworth?
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 Rickmansworth
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.