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What can I build, and will it pay? The planning rules, what neighbours have built, planning decisions, energy upgrades, and whether extending pays.
| Chiswick Park | Hounslow | England and Wales | |
|---|---|---|---|
| Postcodes in a conservation area | 63% | 18% | 10% |
| Postcodes under an Article 4 direction | 99% | 97% | 16% |
| Listed buildings | 28 | 7 | 12 |
| Postcodes in a tree preservation order zone | 0% | 0% | 3% |
| Flats | 69% | 44% | 22% |
planning.data.gov.uk (OGL), Historic England. The rules at one address are on its postcode's Improving page. General guidance, not planning advice.
| Home | Work | Seen | Space added | Rooms |
|---|---|---|---|---|
| 35, Fairlawn Avenue | Extension | 2026 | +51 m² | – |
| 43, Montgomery Road | Extension | 2026 | +27 m² | – |
| 12, Montgomery Road | Extension | 2026 | +46 m² | – |
| 35, Ivy Crescent | Extension | 2026 | +23 m² | 6 → 7 |
| 62, Bollo Lane | Extension | 2026 | +34 m² | 6 → 6 |
| 15, Alwyn Avenue | Extension | 2026 | +39 m² | 7 → 8 |
| 75, Rothschild Road | Extension | 2026 | +50 m² | 4 → 6 |
| 108, Rothschild Road | Extension | 2026 | +22 m² | – |
| 42, Sutton Court Road | Extension | 2026 | +124 m² | 5 → 7 |
| 61a, Bollo Lane | Extension | 2026 | +18 m² | – |
| Work | Chiswick Park | Hounslow | London |
|---|---|---|---|
| All householder applications | 77% (214) | 74% (5222) | 80% |
| Basement | 74% (19) | 73% (82) | 83% |
| Garage conversion or garage | 73% (11) | 78% (107) | 88% |
| Loft or dormer | 69% (72) | 80% (1326) | 81% |
| Other householder work | 65% (26) | 51% (350) | 70% |
| Outbuilding or garden room | 80% (10) | 65% (452) | 79% |
| Rear extension | 92% (24) | 76% (1756) | 79% |
| Side extension | 83% (6) | 69% (127) | 86% |
| Side return or wrap-around | 90% (19) | 84% (243) | 88% |
| Two-storey extension | 91% (11) | 67% (570) | 72% |
| Windows, doors or cladding | 80% (15) | 85% (135) | 90% |
| Porch or front extension | – | 55% (74) | 81% |
Householder applications decided since 2023 (number decided in brackets); withdrawn ones aren't counted. GLA Planning London Datahub.
| Chiswick Park | Hounslow | England and Wales | |
|---|---|---|---|
| Rated A or B | 14% | 12% | 12% |
| Rated E, F or G | 14% | 12% | 16% |
| Homes on mains gas | 73% | 79% | 86% |
| Gas use per home (kWh a year) | 12,049 | 12,470 | 11,043 |
| Households in fuel poverty | 9% | 10% | 10% |
| Homes built before 1919 | 42% | 15% | 20% |
A home's own recommended upgrades and their costs are on its energy certificate, shown on its page.
MHCLG energy certificates; DESNZ fuel poverty.
Across England and Wales, homes extended by a typical 30 m² and then resold rose about 11.1% more than similar homes nearby over the same years (124,884 resales); in London, 15.1% (15,951 resales).
Rough build costs and resale evidence, not quotes or a valuation. How extensions pay off by size, type and region.
The money you don't get back either way, for the same extra space in Chiswick Park.
| Stamp duty on the new home | £32,350 |
|---|---|
| Estate agent on yours 1.2% + VAT | £9,648 |
| Solicitors, buying and selling | £3,000 |
| Survey | £600 |
| Removals | £1,500 |
| Money gone | £47,098 |
| Building, plus 15% for design, planning and contingency | £57,500 |
|---|---|
| Less what it adds to your home's value 60% of the local price | −£106,200 |
| Money gone | −£48,700 |
On these figures, extending loses about £95,798 less. Moving also changes the area, the schools and the commute; extending means months of building work and depends on planning.
Building costs vary a lot (a single-storey rear extension is often £2,000–£3,000 per m², more in London). How much space adds depends on the home and street: what extensions added to resale prices. A guide, not advice; nothing you type leaves this page.
Where people extend most, and where the planning rules are tighter.
| Hounslow Meadows | 48.7 | 0% | 100% | 6 | 7% |
|---|---|---|---|---|---|
| Chiswick North East | 47.7 | 47% | 99% | 118 | 13% |
| Chiswick South East | 47.7 | 60% | 95% | 63 | 4% |
| Heston West | 46.3 | 0% | 98% | 0 | 2% |
| Hounslow East | 45.8 | 0% | 98% | 2 | 2% |
| Hounslow West | 41.4 | 4% | 100% | 2 | 8% |
| Osterley & Lampton East | 40.2 | 19% | 98% | 5 | 5% |
| Heston Central & Lampton West | 37.5 | 4% | 99% | 5 | 14% |
| Cranford | 37.2 | 20% | 95% | 2 | 5% |
| Hanworth North | 34.0 | 1% | 97% | 4 | 4% |
| Heston North | 32.8 | 16% | 99% | 1 | 15% |
| North Hyde & North Cranford | 32.5 | 0% | 81% | 5 | 8% |
| Hounslow Heath | 31.5 | 4% | 97% | 9 | 3% |
| Syon Green | 30.8 | 14% | 98% | 30 | 20% |
| Brentford West & Osterley Park | 30.7 | 58% | 94% | 24 | 8% |
| Lower Feltham | 29.6 | 5% | 98% | 2 | 6% |
| Isleworth & Ivybridge | 29.2 | 42% | 95% | 27 | 16% |
| Chiswick South West | 27.9 | 68% | 98% | 38 | 3% |
| Brentford Central | 26.5 | 31% | 97% | 54 | 33% |
| Feltham East | 26.3 | 10% | 97% | 1 | 6% |
| Hanworth South | 25.5 | 5% | 98% | 14 | 2% |
| Spring Grove | 25.2 | 21% | 97% | 7 | 23% |
| Chiswick Park (this one) | 24.9 | 63% | 99% | 28 | 14% |
| Bedfont | 23.6 | 21% | 97% | 16 | 7% |
| North Feltham & Hatton | 23.5 | 0% | 95% | 6 | 5% |
| Brentford East | 21.5 | 11% | 99% | 8 | 38% |
| Feltham Central | 14.3 | 7% | 100% | 9 | 16% |
| Hounslow High Street | 12.7 | 4% | 100% | 2 | 21% |
| Kew Bridge & Gunnersbury Park | 12.1 | 21% | 96% | 20 | 55% |
| II |
| 330 m |
Nearest 12 shown. Grade I and II* are the most important few per cent. Listing means consent is needed for most changes, inside and out. Contains Historic England data © Historic England 2026 (via planning.data.gov.uk), OGL.
| Extension |
| 2026 |
| +21 m² |
| 2 → 4 |
| 80, South Parade | Extension | 2026 | +28 m² | – |
|---|
| 27, Cedars Road | Extension | 2026 | +16 m² | 6 → 6 |
|---|
| 286a, Chiswick High Road | Extension | 2026 | +33 m² | – |
|---|
| 44, Wavendon Avenue | Extension | 2026 | +32 m² | 9 → 7 |
|---|
| 70, Wavendon Avenue | Extension | 2026 | +132 m² | – |
|---|
| 7a, Thorney Hedge Road | Extension | 2026 | +53 m² | 2 → 4 |
|---|
| 71, Barrowgate Road | Extension | 2026 | +23 m² | 9 → 10 |
|---|
| 20, St Albans Avenue | Extension | 2026 | +55 m² | 6 → 7 |
|---|
| 4, Rusthall Avenue | Extension | 2026 | +18 m² | 10 → 8 |
|---|
| 13, Evelyn Road | Extension | 2026 | +20 m² | 6 → 6 |
|---|
| 14a, Cambridge Road North | Extension | 2026 | +19 m² | – |
|---|
| 13, Ravenswood Court, Stanley Road | Extension | 2026 | +27 m² | – |
|---|
| 47, Priory Road | Extension | 2026 | +25 m² | – |
|---|
| 11, Whitehall Gardens | Extension | 2026 | +10 m² | 7 → 7 |
|---|
| 57, Duke Road | Extension | 2026 | +21 m² | – |
|---|
| 6, Edmunds House, Colonial Drive | Extension | 2025 | +26 m² | – |
|---|
| 19, Montgomery Road | Extension | 2025 | +83 m² | – |
|---|
| 63, Ivy Crescent | Extension | 2025 | +10 m² | 9 → 8 |
|---|
| 52, Bollo Lane | Extension | 2025 | +12 m² | 5 → 6 |
|---|
Not every extension shows here. We only see building work when a new energy certificate is lodged, which happens when a home is sold, let or newly built. A loft or extension added since then won't appear, even with planning permission and building control sign-off, because those records aren't published as open data outside London. Missing work doesn't mean missing paperwork.
From energy certificates: an extension where a later certificate shows more floor space, a loft conversion where roof rooms appear.
Sort by any column; open a neighbourhood for the same view.
| Neighbourhood | Council | England and Wales | |
|---|---|---|---|
| Homes with solar panels | 0.0% | 0.4% | 1.2% |
| Heated by a heat pump | 0.4% | 0.6% | 1.0% |
| Mains gas | 60.1% | 74.4% | 84.0% |
| Oil or LPG | 0.0% | 0.1% | 4.1% |
| Electric heating | 19.3% | 13.5% | 8.3% |
| Community heating | 20.1% | 11.3% | 2.1% |
From each home's latest energy certificate, so panels or heat pumps fitted since aren't counted and the shares are lower than today's real figures. Compare areas in the data explorer.