Conservatory replacement extensions in Isleworth
If you live in Isleworth and want more space without moving, a conservatory replacement is one of the most practical ways to get it. We handle the drawings, approvals and the build.
- Guide price in IsleworthFrom £26,000 inc VAT
- PlanningOften permitted development (3–4 m), or prior approval up to 6–8 m
- Build time8–14 weeks on site
- Postcode districtsTW1, TW3, TW4, TW5, TW7
Will the council need to approve it?
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.
Homes in conservation areas, national parks, National Landscapes (formerly AONBs), the Broads and World Heritage Sites have tighter rules, so we always check the property's status and planning history before design starts.
Building regulations approval is separate from planning. In England you can use the council's building control team or a registered building control approver; a full plans application gets the drawings checked before work starts, and the inspector signs the work off with a completion certificate.
Applications are decided by the local planning authority (your district, borough or unitary council).
Covering Isleworth
Across TW1, TW3, TW4, TW5, TW7, TW8, we can visit, measure and advise. Nearby, we also take on projects in Hounslow (1 mile), Heston (2 miles), Richmond (2 miles), Southall (3 miles).
For homes towards Surrey, East Molesey is around 5 miles away. Across London, terraced houses with narrow side returns and tight access are the norm, which shapes everything from party wall notices to how materials reach the back garden.
What is included
- Glazing and doors to suit the new room
- Opening widened into the house if wanted
- Insulated walls and roof to current regulations
- New or upgraded foundations
- Removal and disposal of the old conservatory
- Trial holes to check the existing foundations
A replacement is a chance to rethink the shape. Many conservatories are oddly proportioned; for a similar cost the new room can often be squarer, wider or better connected to the kitchen.
Conservatory replacement prices in Isleworth
These guide figures apply our London adjustment (×1.3) to national rates. They include VAT at 20% and cover the build itself; design and council fees are listed separately.
Typical rates in Isleworth: £2,400 to £4,550 per m² including VAT, depending on specification.
| Size | Essential | Standard | Premium |
|---|---|---|---|
| 3 m × 3.3 m 10 m² | £26,000 – £31,000 | £27,500 – £36,000 | £35,500 – £45,500 |
| 3.5 m × 4 m 14 m² | £33,500 – £40,500 | £39,000 – £50,500 | £50,000 – £64,000 |
| 4 m × 5 m 20 m² | £48,000 – £57,500 | £55,500 – £71,500 | £71,500 – £91,000 |
Includes removal of the old conservatory. Reusing existing foundations is only possible after investigation.
Want a range for your exact size? The guide-price tool takes about a minute.
How the project works
Site visits are free and there is no obligation. Where drawings are needed, the design stage is priced in writing before it starts.
Free site visit
It starts with a visit to your house to measure, check access and talk through ideas and budget.
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.
Common questions in Isleworth
How long does a conservatory replacement take to build in Isleworth?
On site, typically 8 to 14 weeks once approvals are in place. Before that, allow 4–12 weeks design and approvals.
Do you cover all of Isleworth?
Yes. We cover Isleworth and the surrounding parts of Greater London. Site visits are free and there is no obligation.
Who do I contract with for a conservatory replacement in Isleworth?
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.
Does replacing a conservatory need planning permission?
A solid replacement is treated as a new extension, so it must meet the permitted development limits or get planning permission, and it always needs building regulations approval.
Can I keep the existing base?
Sometimes, but conservatory bases are often too shallow for solid walls. Trial holes tell us before we confirm the price.
Book a free site visit in Isleworth
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.