House Extensions Ruislip
Single storey rear and double storey extensions in Ruislip, planning, structure and build under one contract.
- Rated 4.9 from 31 reviews on MyBuilder
- Single-storey rear extension from £40,000
- Free site survey, itemised quote
GS Renovation plans and builds extensions across Ruislip, making the most of the generous plots that came with the area's interwar houses. We handle everything from foundations and steel to the final fit-out under one accountable team.
In Ruislip, a single-storey rear extension typically starts from £40,000, or £2,000 to £2,800 per m² (indicative London ranges, Architecture for London, Resi, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Ruislip: the structural engineer we appoint designs the structure, we build it, and building control signs it off.
Price guide
| Work | Indicative London range |
|---|---|
| Single-storey rear extension | from £40,000 |
| Rear extension, per m² | £2,000 to £2,800 |
| Side return, per m² | £2,400 to £3,200 |
| Wraparound, per m² | £2,400 to £3,200 |
| Double storey, per m² | £1,800 to £2,600 |
| Basement extension | see the basement page |
Indicative London ranges (Architecture for London, Resi, MyBuilder and Checkatrade, 2026), not a quotation. Prices checked September 2026. Full breakdown: Extension Costs & Planning.
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Ruislip range: choose above
Rear and side-return extensions in Ruislip
Many Ruislip semis sit on deep, wide plots, which makes them well suited to single and double storey rear extensions and to filling in the side passage between paired houses. A rear extension can turn a cramped 1930s kitchen into an open-plan kitchen-diner opening onto the garden, while a wrap-around combines the rear and the side return for a much larger ground floor. We set out the groundworks, pour the foundations and build up in brick to match the interwar character.
Where the extension removes an external wall to connect old and new, we install a steel beam sized by a structural engineer and bearing onto padstones, then take the new roof, whether flat, pitched or a lantern rooflight, up to a weathertight finish. On a paired Ruislip semi the flank or rear wall is often a party wall, so the Party Wall Act applies and you serve the notices your neighbour is entitled to receive before we break ground.
Housing in Ruislip
The Council Tax list puts Ruislip at about 20,620 homes, 27% flats against 73% houses; 1% went up before 1919, 52% between the wars and 47% after 1945. Terraced houses make up 30% of homes here, and a rear extension on a terrace in Ruislip digs foundations close to both neighbours, so notices to both are normal.
Side extensions and trees in the Ruislip Village Conservation Area
In a conservation area a side extension to a house is not permitted development, so it needs planning permission. Hillingdon's leaflet for the Ruislip Village Conservation Area says side extensions should normally be set back from the original building line. For a semi that shapes the design from the start: the front wall of the extension steps back from the house, and the roof usually drops below the main ridge. Set back the front and the room behind is shorter, so the useful space comes from width and from the rear. The same leaflet requires six weeks notice, a Section 211 notice, to prune, lop or fell a tree in a conservation area. A tree near the footprint that needs cutting back therefore needs notice long before the foundations are dug, and its roots may still set the foundation depth.
Everywhere in Ruislip the rear depth has a borough-wide limit too. Hillingdon's Article 4 Direction removes permitted development rights for residential extensions that extend beyond the rear wall of the original dwelling by more than 4 metres, and it came into force on 22 September 2014. The ordinary single storey allowance is 3 metres for a semi or terrace and 4 metres for a detached house. Measure from the original rear wall, not from an earlier addition, and for an interwar house original means as it stood when the modern planning system began after the war. Mark that line on the drawings before deciding whether the scheme needs a planning application.
Planning and permitted development in Ruislip
Not every Ruislip extension needs a planning application. Many single storey rear extensions fall under permitted development, which lets you build within set size and height limits without full planning permission, though the exact allowance depends on your plot and whether earlier owners have already extended. Larger schemes, most double storey work, and anything affecting the front or a prominent side elevation usually need a full planning application to Hillingdon Council, and permitted development rights can be restricted on certain roads.
We assess your specific house early, tell you honestly whether it is permitted development or a planning application, and coordinate the route with the council either way. Whichever path applies, the structural and building work itself is governed by building regulations, so foundations, steel, drainage and insulation are all inspected by building control. From first drawings to the full internal fit-out, plastering, electrics, plumbing and decoration, one team sees the extension through.
Kitchen extensions in Ruislip
47% of the houses in Ruislip are semi-detached or detached, which usually leaves room for a kitchen extension across the full rear width, with a steel beam over the opening into the house. The fit-out is priced on its own page, kitchen renovation in Ruislip; the build figures are in the table above.
Double storey extensions in Ruislip
Under permitted development a two-storey rear extension can go no more than 3 metres beyond the original rear wall and must stay at least 7 metres from the rear boundary, and in a conservation area it is not permitted development at all. Many gardens are too short for the 7 metre rule, so a double storey extension in Ruislip often needs planning permission from Hillingdon Council. With 34% of homes here semi-detached or detached, the side of the house is often an option too. Hillingdon's Ruislip Village Conservation Area leaflet says side extensions should normally be set back from the original building line (council source). Our double storey extension page explains the build, at £1,800 to £2,600 per m² across both floors.
- Building control inspections at foundation, damp course and steel stages
- Drainage diversion and build-over agreements with the water authority
- First fix and second fix plumbing and electrics throughout
VOA Council Tax stock of properties, March 2025, for all 6 statistical areas in Ruislip. Counts rounded by the VOA.
Trusted House Extensions in Ruislip
Ruislip homeowners choose GS Renovation because we make the most of the area's larger interwar plots without cutting corners. We tell you upfront whether your extension is permitted development or needs a planning application to Hillingdon Council, plan the programme around the party wall notices you serve on paired semis, and deliver foundations, steel, roof and fit-out under one team led by a founder with 30+ years on the tools.
- Itemised pricing, so you can see what every stage costs
- Insulation and thermal detailing to current regulations
- Building control inspected at foundation, damp course and steel stages
Built a new extension at rear of property. Laid foundations, drainage, raised floor, new roof and completed all fixtures and interior decoration…
The kitchen has been fitted to the high standard. Saaid was polite, professional, tidy, he pays attention to a little details that make huge…
Saiid did a complete refurbishment of our small bathroom. This involved ripping out the existing bath/shower, basin, toilet, pipework, and tiles and…
FAQ
Frequently Asked Questions about House Extensions Ruislip
Can I get a fixed price for house extensions at an HA4 address?
Fixed pricing is the default for house extensions in Ruislip, not the exception. What prevents it is real uncertainty about the structure at the HA4 address, and then GS Renovation prices the investigation first and the job afterwards, within £2,000 to £2,800 per m² for a rear extension (indicative). Once it is done, the build follows its set sequence: drainage under the footprint is diverted before foundations are poured.
Does my Ruislip extension need planning permission or is it permitted development?
Many single storey rear extensions in Ruislip fall under permitted development within set size and height limits, so no full planning application is needed. Larger or double storey schemes, and work affecting the front elevation, usually need planning permission from Hillingdon Council. We assess your specific plot first and handle whichever route applies, alongside the building regulations sign-off the structure requires.
Do trees near my Ruislip extension change the foundations?
They can, a great deal. On clay subsoil, roots draw moisture and make the ground shrink and swell, so foundations near trees are dug deeper than a standard strip, sometimes much deeper. The neighbour's trees count too. Hillingdon Council building control inspects the trench before concrete is poured, and can ask for more depth there and then, so the engineer checks trees at design.
Can a Ruislip extension be built over a drain?
Only with the right consent. If a public sewer runs under the footprint, building over or near it needs the water company's agreement before work starts, and that can shape the extension's size. A private drain is simpler: it is rerouted or given an access chamber, with falls set under Part H. Lift the manhole covers at survey, before any drawings are fixed.
What does a wrap-around extension on a Ruislip semi involve structurally?
Removing both the rear wall and the side wall of the house at the corner, which leaves the corner of the upper floor with nothing beneath it. The engineer designs a steel frame, often a goalpost or a corner post on its own foundation, to take that load. The side section is usually near the boundary, so a party wall notice is likely.
Which inspections does a Ruislip extension go through?
Hillingdon Council building control calls in at each point where work is about to disappear: the dug trench, drain runs while still open, the damp course and slab, the steel where the house is opened up, and insulation before boarding. A final visit issues the completion certificate. Programme the build around these calls, because an inspector who arrives after concrete is poured can ask for it to be broken out.
How does the size of a Ruislip extension affect the building control charge?
Hillingdon bands it by floor area. A domestic extension of less than 40m2 has one total charge, for full plans or building notice, and a domestic extension of 40m2 to 60m2 has a higher one. A wrap-around on a Ruislip semi can cross that line by a small margin. Fix the footprint on the drawings before applying, so the charge matches what is built and nothing needs revising mid job.
Will a large extension in Ruislip be charged the Community Infrastructure Levy?
Only if it adds 100m2 of new floorspace or creates an extra dwelling, which is when the CIL applies in Hillingdon. The indexed rate for residential dwelling houses is set per square metre. A two storey side and rear addition on a detached Ruislip house can come close to the threshold. An extension to your own home can usually claim relief, but only if the claim and a commencement notice reach Hillingdon before work begins, so calculate the new floorspace at design stage.
How fast can Hillingdon confirm a Ruislip extension is permitted development?
Hillingdon's fast-track service determines householder lawful development certificate applications within 21 days of receiving the fast-track fee. For an extension close to its permitted depth, that written certificate settles the question before the steel, windows and roof are ordered, and it answers a buyer's solicitor later. Inside Ruislip Village or Ruislip Manor Way fewer extensions qualify, since side and two storey additions need planning there, but a single storey rear extension within its depth can still be confirmed this way.
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