Kitchen Extensions Hillingdon

In Hillingdon, 25% of homes are terraced houses and 36% are semi-detached or detached, and a house has the permitted development rights a flat lacks. The borough sets its own limits: Policy DMHD 1 says a single storey rear extension on a terrace or semi should not exceed 3.3 metres deep on a plot of 5 metres or less, and 3.6 metres on a wider plot. A borough-wide Article 4 Direction on large rear extensions has also been in force since 22 September 2014. We build the shell, the steel and the kitchen as one programme.

In Hillingdon, 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 Hillingdon: 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 deep a Hillingdon kitchen extension can go at the back

The depth is set by plot width and house type before anything else. Hillingdon Policy DMHD 1 says a single storey rear extension on a terraced or semi-detached house should not exceed 3.3 metres deep where the plot is 5 metres wide or less, or 3.6 metres on a wider plot. For a detached house the figure is 4.0 metres. Measure your plot at the rear wall before a designer draws anything, because a few centimetres either side of 5 metres changes the depth your kitchen can have, and so where the island, the table and the glazing can sit.

National permitted development allows a single storey rear extension of three metres beyond the original rear wall of a semi or terrace, and four metres for a detached house. In Hillingdon an Article 4 Direction removes permitted development for extensions that go more than 4 metres beyond the original rear wall, so the larger home extension route, which needs prior approval, stops at 4 metres here for a semi or terrace. Within three metres no application is needed, though a lawful development certificate confirms it. Between three and 4 metres the prior approval comes first, and anything larger needs a householder application. Either way the drawings we build from should show the original rear wall clearly, because that line is where every measurement starts.

Housing in Hillingdon

On the valuation list Hillingdon counts about 118,240 homes, 34% flats and 66% houses; 4% predate 1919, 37% are interwar and 59% post-war. A semi in Hillingdon can take its kitchen extension across the back and round into the side passage, which leaves room for a utility behind the kitchen, and 27% of homes here are semi-detached.

Side returns, wraparounds and height limits in Hillingdon

A side extension in Hillingdon should not exceed half the width of the original property under Policy DMHD 1, which matters on interwar semis where the side passage is the only route to the garden. 37% of the borough's homes were built between 1919 and 1939, and on an interwar semi a wraparound kitchen combines a rear addition with a narrow side infill. The side part often takes the kitchen run, with dining in the rear section, so the half-width limit decides whether a full-height larder wall fits or whether the run turns into the rear.

Height is the second limit. Hillingdon says a flat roofed single storey extension should not exceed 3.0 metres high, or 3.4 metres with a pitched or sloping roof, measured from ground level. On a sloping garden that measurement point changes the finished floor level you can have inside, so we set out levels on site before the slab is poured and check them against the drawn heights. A pitched roof gives a little more headroom for roof windows, while a flat roof with a lantern keeps the eaves low against the neighbour's boundary.

Conservation areas and parapets on Hillingdon kitchen extensions

Hillingdon has 31 designated conservation areas, and inside them the design rules tighten. Under permitted development rules all side extensions on designated land, such as a conservation area, need householder planning permission, so a side return in Ruislip Village or Hayes Village is always an application. Hillingdon's Ruislip Village Conservation Area leaflet adds that side extensions should normally be set back from the original building line, which trims a little floor area off the side section and moves the wall your worktop runs against.

Where the extension has a flat roof, Hillingdon expects a parapet in conservation areas and Areas of Special Local Character. A parapet changes the build: the wall rises above the roof deck, the roof falls to a hidden gutter or outlet, and the membrane detail at the upstand has to be right first time. It also changes how roof lights sit, since a low-profile unit can disappear behind the parapet line. We price that detail from the drawings rather than treating it as a standard flat roof, so the programme holds.

Drainage, steel and the fit-out in one Hillingdon programme

Opening the back of a Hillingdon house into the new kitchen usually means a steel beam across the old rear wall, and that steel needs structural calculations. A Hillingdon full plans application needs detailed plans and structural calculations, and you will normally receive a formal decision within 5 weeks. The structural engineer we appoint sizes the beam and padstones, and we order the steel once the calculations are approved, so the opening, the kitchen layout and the inspections line up. Where the new foundations or steel bearings come close to a neighbour, you serve the Party Wall Act notices. For a council-owned house next door they go to the Mayor and Burgesses of The London Borough of Hillingdon.

Drainage is the other early job. A kitchen that moves to the back of the extension takes its sink and dishwasher waste further from the existing stack, and any manhole or run under the new floor has to be found, surveyed and diverted or protected before the slab. Building over or near a public sewer needs the sewerage company's agreement. We sequence the fit-out behind that: first fix plumbing and wiring in the new walls, plastering, then units, worktop templating and appliances, with a registered electrician certifying the new circuits. Keeping the builder and the kitchen fitter as one team avoids the gap where the shell is finished and nobody owns the snagging.

• Airbrick ducts to keep existing timber floors ventilated
• Steel beams and goalpost frames into the existing house
• Wet underfloor heating laid in the new screed

VOA Council Tax stock of properties, March 2025, for all 32 statistical areas in Hillingdon. Counts rounded by the VOA.

Next steps that tend to follow kitchen extensions in Hillingdon: kitchen renovation in Hillingdon, our Hillingdon area guide, fitting the kitchen itself, party wall notices for a kitchen extension, how we handle kitchen extensions across London and Kitchen-Diner Layout Ideas.

Why Choose GS Renovation in Hillingdon

You would use GS Renovation for a Hillingdon kitchen extension because one team runs it from the first dig to the last worktop. Abdelaaziz Saaid, the founder, has spent his working life on hands-on building work, and he sees the job through the structural steel, the roof detail and the kitchen fit-out. We build to the consent and the approved drawings you or your designer obtain, give you a written programme before work starts, and coordinate the structural engineer we appoint, the building control inspections and the trades that follow the shell.

• Cooker extract taken outside through the new roof or flank wall, not recirculated
• Building control and Part P certificates handed over together at the end
• Fully insured, with cover in place on every site

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.