Kitchen Extensions Isleworth

A kitchen extension in Isleworth starts with the house type, because the stock here mixes terraces, semis and a large share of flats. 30% of homes here are terraced houses and 13% are semi-detached or detached, so the side return on a terrace and the rear addition on a semi are the two shapes to plan for. Hounslow publishes its own depth limits for single storey rear extensions, and a flat owner has no householder permitted development rights for an extension. We build the shell, the steel and the kitchen as one programme.

In Isleworth, a rear kitchen extension of about 30 square metres typically costs £45,000 to £97,500 excluding VAT, or £60,000 to £100,000 for a side return (indicative London ranges, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Isleworth: the structural engineer we appoint designs the foundations and steel, we build the room and fit the kitchen, and a registered electrician certifies the electrics.

How far back a TW7 rear kitchen extension can go

In Isleworth, Hounslow's guidelines set the depth before anything else is drawn. Its residential extension guidelines give a maximum single storey rear depth of 3.05m for a terraced house, 3.65m for a semi-detached house and 4.25m for a detached one. Those numbers shape the kitchen plan: on a terrace, 3.05m of new floor usually means the island sits in the old footprint and the new part carries the table and the glazing.

Separately, national permitted development allows a single storey rear extension of three metres beyond the original rear wall of an attached house, or four metres for a detached one, with a four metre height cap. Your designer decides which route fits the house and the neighbours. We price from the drawings they settle on, and the depth decides how long the steel runs, where the roof lights fall and how much new drainage sits under the slab.

Housing in Isleworth

About 13,670 homes are listed for Isleworth, and the mix is 44% houses to 56% flats, with 61% built after 1945, 21% in 1919 to 1939 and 19% earlier. Most homes here are flats, and only a ground floor flat in Isleworth with its own garden can extend its kitchen.

Side return infills beside an Isleworth outrigger

On an Isleworth terrace with a back addition, the side return infill is the extension that turns a narrow galley kitchen into a proper room with space for a table. Hounslow's guidance deals with it directly: where an infill beside an outrigger goes beyond the borough's maximum depths, its eaves on the shared boundary should not exceed two metres and the roof pitch should not exceed 45 degrees. Those two numbers govern the section drawing.

Because that limit sits on the boundary, the section drawing usually shows a low wall to the neighbour and a roof rising into the house. For us it sets the build detail: the frame or steel that carries the opened outrigger wall, designed by the structural engineer we appoint, a parapet or gutter that stays under the eaves line, and roof glazing sized to the pitch. Building on or near the shared wall can bring the Party Wall Act in, and the building owner serves those notices. The wall units then go on the outrigger side, where the full height is.

Old Isleworth riverside homes and conservation area rules

Homes inside the Isleworth Riverside Conservation Area need more care before the kitchen is designed. The area was designated on 11 November 1972 and its south western boundary was extended on 13 July 1993. In a Hounslow conservation area, front and side extensions of one storey or more, and two storey rear extensions, need planning permission. That rules out the permitted development route for a side infill on these streets, and it brings the design of the new elevation into the planning assessment from the start.

In practice a side extension on a house inside the conservation area goes through a planning application rather than permitted development, and the materials on the elevations get looked at. We match brick, bond and mortar to the existing house, and we build the glazing to the approved drawing rather than swapping in a standard system. Allow for that application in the programme before any site start date is fixed, and keep the kitchen order until the consent is in hand, because a condition on materials can change the glazing.

Drains, building control and the flat roof

The drainage under an Isleworth garden can decide the building control route. Hounslow requires a full plans application, not a building notice, where an extension is built over or within 3m of a public drain or sewer. A terrace can share a run along the backs, so we check the sewer map and lift the manhole covers before the design is final. If the run needs diverting or a build over agreement, that work goes at the front of the programme, ahead of the foundations.

The flat roof also has a limit. Hounslow's guidelines say schemes that use the flat roof of a single storey rear extension as a balcony or terrace are normally refused, so plan the roof as a roof, with lights and a green or membrane finish. Where Hounslow is the building control body, inspections are booked with at least 1 working day's notice, and it issues a completion certificate once the work is inspected, which you keep with the deeds.

• Foundations, drainage and slab with the kitchen services cast in
• Cooker hood extraction ducted through the roof or flank wall
• Airbrick ducts to keep existing timber floors ventilated

VOA Council Tax stock of properties, March 2025, for Isleworth & Ivybridge, Syon Green and Spring Grove. Counts rounded by the VOA.

When comparing kitchen extensions in Isleworth with other work, it helps to read kitchen renovation in Isleworth, kitchen extensions across Hounslow, fitting the kitchen itself, the Party Wall Act on a boundary build, how we handle kitchen extensions across London and Planning a Kitchen Island.

The GS Renovation Difference in Isleworth

You get one firm for the structure and the kitchen, so the steel, the drainage runs and the appliance positions are fixed together before the slab goes in. The structural engineer we appoint sizes the beams, a registered electrician certifies the new circuits, and a registered gas engineer moves any gas supply. We work from your designer's approved drawings, book the building control inspections at each stage, and hand over the completion paperwork with the finished kitchen.

• Rooflights set out against the engineer's steel layout
• Boiler flue, soil pipe and gully moved off the rear wall in the right order
• Honest updates if a date or a detail has to move

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.