House extensions in Hillingdon

Hillingdon received 1,596 householder applications in the last 12 months - about 31 a week. Rear extensions and dormers are the most common. Of the 1,332 decided so far, 1,210 were approved. If you're planning your own, the applications below show what people nearby applied for and how the council decided.

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Showing 50 of 361 applications
21 Oct 2026 Undecided 49385/APP/2026/2193

20 Mill Road West Drayton

Single dropped kerb to be created at the front of the property which is on a classified road.

Hillingdon
21 Oct 2026 Undecided 45080/APP/2026/2372

165 Cowley Road Uxbridge

Conversion of roof space to habitable use to include a rear dormer with Juliette balcony and Hip to Gable roof extension with 2 front roof lights foll...

Hillingdon
19 Oct 2026 Undecided 45516/APP/2026/2173

Mondial House, 5 Mondial Way Harlington

Two storey roof extension to the existing building to provide 28 apart-let room (C1 use class), associated facilities, cycle parking and refuse

Hillingdon
16 Oct 2026 Undecided 80125/APP/2026/1954

50 Mayfield Close Hillingdon UB10 0DU

Erection of an two storey extension to the rear, conversion of garage into habitable accommodation, and amendments to fenestrations.

Hillingdon
15 Oct 2026 Undecided 68474/APP/2026/2382

54 Pinkwell Lane Hayes UB3 1PH

Erection of outbuilding to rear garden, following the demolition of the existing outbuilding.

Hillingdon
15 Oct 2026 Undecided 80312/APP/2026/2420

142 Raynton Drive Hayes UB4 8BQ

Proposed loft conversion to habitable use to include a hip to gable, rear dormer, 2 front roof lights and a side gable end window (Application for a C...

Hillingdon
15 Oct 2026 Undecided 25604/APP/2026/2361

23 Hoylake Crescent Ickenham

Erection of a front porch

Hillingdon
15 Oct 2026 Undecided 4903/APP/2026/2364

12 Whiteheath Avenue Ruislip

Conversion of roof space to habitable use to include hip to gable roof extensions of both sides, rear dormer, 3x front roof lights, gable end window, ...

Hillingdon
14 Oct 2026 Undecided 74783/APP/2026/2404

2 Crosier Way Ruislip HA4 6HF

Demolition of conservatory and erection of single storey rear and part double storey side extensions.

Hillingdon
14 Oct 2026 Undecided 35794/APP/2026/2408

29 St Peter's Road Cowley Uxbridge

Erection of front porch extension (Application for a Certificate of Lawful Development for a Proposed Development).

Hillingdon
14 Oct 2026 Undecided 504/APP/2026/2346

82 Raleigh Avenue Hayes

Erection of single storey rear extension following the demolition of existing rear single storey structure (Application for a Certificate of Lawful De...

Hillingdon
14 Oct 2026 Undecided 20454/APP/2026/2323

112 Linden Avenue Ruislip

Conversion of garage into habitable room

Hillingdon
13 Oct 2026 Undecided 2773/APP/2026/2406

60 East Avenue Hayes

Construction of Double Storey Side Extension, single storey rear extension, part first floor rear extension, and loft conversion involving constructio...

Hillingdon
13 Oct 2026 Undecided 46555/APP/2026/2401

42 Burnham Avenue Ickenham

Proposed works comprise a Single-storey rear extension and a loft conversion incorporating a rear dormer with a hip-to-gable roof along a front porch.

Hillingdon
13 Oct 2026 Undecided 35987/APP/2026/2397

3 Dell Road West Drayton

Erection of a new outbuildin which will be used solely for purposes incidental to the enjoyment of the existing dwellinghouse, including recreational ...

Hillingdon
12 Oct 2026 Undecided 46371/APP/2026/2384

3 Hedgeside Road Northwood

Erection of a single storey rear extension, following the demolition of the existing conservatory. Landscaping to the rear garden including the erecti...

Hillingdon
12 Oct 2026 Undecided 80305/APP/2026/2386

28 Cowley Crescent Cowley UB8 2HE

Erection of single storey front extension, a part single part two storey rear extension, a part single part two storey side extension, removal of exis...

Hillingdon
12 Oct 2026 Undecided 12457/APP/2026/2383

12 Thornhill Road Ickenham

Erection of a part single part two storey side and rear extension, a single storey front extension, a redesign of the roof to include a crown roof, am...

Hillingdon
12 Oct 2026 Undecided 78501/APP/2026/2388

117 Wentworth Crescent Hayes UB3 1NP

Erection of a part single, part two storey extension to the rear, erection of outbuilding to the rear

Hillingdon
12 Oct 2026 Undecided 26897/APP/2026/2389

7 Croyde Avenue Hayes

Erection of a part single part two storey wrap around extension to the side and rear

Hillingdon
12 Oct 2026 Undecided 78501/APP/2026/2390

117 Wentworth Crescent Hayes UB3 1NP

Single storey rear extension, front porch extension and the erection of an outbuilding at the rear of the garden garden (Application for a Certificate...

Hillingdon
12 Oct 2026 Undecided 49177/APP/2026/2185

5 Moor Park Road Northwood

Erection of an outbuilding (Application for a Certificate of Lawful Development for a Proposed Development)

Hillingdon
12 Oct 2026 Undecided 39779/APP/2026/2127

65 New Road Hillingdon

Erection of an extension to existing outbuilding.

Hillingdon
12 Oct 2026 Undecided 68075/APP/2026/2161

31 Lees Road Uxbridge UB8 3AS

Erection of a single-storey rear extension.

Hillingdon
9 Oct 2026 Undecided 75361/APP/2026/2370

47 Cleave Avenue Hayes UB3 4HA

Erection of a front porch

Hillingdon
9 Oct 2026 Undecided 39049/APP/2026/2380

91 Gledwood Drive Hayes

Conversion of flat roof to gable end roof with Window, incorporating a rear dormer and two front roof lights to create habitable roof space.

Hillingdon
9 Oct 2026 Undecided 27649/APP/2026/2369

61 Warley Avenue Hayes

Erection of a front porch, single storey side and rear extension.

Hillingdon
9 Oct 2026 Undecided 7848/APP/2026/2377

22 Mansfield Drive Hayes

Proposed development of the conversion of the existing roof space to habitable use, including a hip-to-gable roof enlargement, rear dormer extension, ...

Hillingdon
9 Oct 2026 Undecided 30026/APP/2026/2379

15 Abbotsbury Gardens Eastcote Pinner

Erection of a single storey rear extension, which would extend beyond the rear wall of the original house by 4.00 metres, for which the maximum height...

Hillingdon
9 Oct 2026 Undecided 3063/APP/2026/2378

Heathrow Park Thistle Hotel Bath Road Longford

Replacement of external materials from brick to cladding and canopy soffit, with new LED lighting to replace existing downlighters.

Hillingdon
9 Oct 2026 Undecided 32401/APP/2026/2317

8 Belmont Road Uxbridge

Erection of a part two-storey side and rear extension, single-storey rear extension with alteration to roof form, and conversion of the existing garag...

Hillingdon
8 Oct 2026 Undecided 80107/APP/2026/2293

14 Falling Lane Yiewsley UB7 8AD

Erection of a single storey extension to the rear, following the conversion of the detached garage to habitable use

Hillingdon
8 Oct 2026 Undecided 75679/APP/2026/2368

85 Mill Road West Drayton

Erection of a detached single-storey outbuilding within the rear garden.

Hillingdon
8 Oct 2026 Undecided 39785/APP/2026/2366

27 Coronation Road Hayes Middlesex

Erection of a first floor side and rear extension.

Hillingdon
8 Oct 2026 Undecided 10466/APP/2026/2362

18 Whiteheath Avenue Ruislip

Conversion of garage into habitable space including amendments to fenestrations (Application for a Certificate of Lawful Development for a Proposed De...

Hillingdon
8 Oct 2026 Approved 23 Oct 9528/APP/2026/2365

4 Burleigh Road Hillingdon

Proposed hipped to gable loft conversion with rear dormer, a side facing window and 2 front roof lights (Application for a Certificate of Lawful Devel...

Hillingdon
8 Oct 2026 Undecided 21390/APP/2026/2224

68 Tudor Road Hayes

Erection of a double-storey side and side/rear extension

Hillingdon
8 Oct 2026 Undecided 15355/APP/2026/2294

81 Raeburn Road Hayes

Erection of a single storey rear extension, which would extend beyond the rear wall of the original house by 4.00 metres, for which the maximum height...

Hillingdon
7 Oct 2026 Undecided 51502/APP/2026/2357

21 Spencer Avenue Hayes

Erection of a first floor extension to the rear

Hillingdon
7 Oct 2026 Undecided 73052/APP/2026/2360

16 Cranborne Waye Hayes Middlesex UB4 0HW

Proposed single-storey detached outbuilding in the rear garden, featuring a dual-pitched roof with integrated rooflights, for incidental residential u...

Hillingdon
7 Oct 2026 Undecided 47909/APP/2026/2334

10 Hillingdon Hill Hillingdon

Erection of a single storey rear extension, which would extend beyond the rear wall of the original house by 4.00 metres, for which the maximum height...

Hillingdon
7 Oct 2026 Undecided 32824/APP/2026/2358

116 Botwell Common Road Hayes

Erection of a rear garden outbuilding

Hillingdon
7 Oct 2026 Approved 16 Oct 80280/APP/2026/2307

39 Chaucer Avenue Hayes UB4 0AR

Erection of outbuilding to rear garden for use as a gym, shower room, and garden store (Application for a Certificate of Lawful Development for a Prop...

Hillingdon
7 Oct 2026 Undecided 72670/APP/2026/2228

148 Windsor Avenue Uxbridge UB10 9BD

Erection of outbuilding (Part-retrospective)

Hillingdon
7 Oct 2026 Undecided 6436/APP/2026/2273

17 Ferndale Crescent Cowley Uxbridge

Erection of a single storey wrap around extension to the side and rear, conversion of integral garage to habitable accommodation.

Hillingdon
6 Oct 2026 Undecided 34556/APP/2026/2353

54 Church Road Hayes

Proposed part double storey rear extension and conversion of roof space to habitable use

Hillingdon
6 Oct 2026 Undecided 7848/APP/2026/2350

22 Mansfield Drive Hayes

Erection of a single storey extension to the rear

Hillingdon
6 Oct 2026 Undecided 234/APP/2026/2343

98 Breakspear Road South Ickenham

SAP Validated - Conversion of roof space to habitable use to include a rear dormer, 3no. front roof lights, 1no. rear roof light, conversion of roof f...

Hillingdon
6 Oct 2026 Undecided 80297/APP/2026/2355

6 Dudley Drive Ruislip HA4 6QN

Erection of a single storey rear extension, which would extend beyond the rear wall of the original house by 4.00 metres, for which the maximum height...

Hillingdon
6 Oct 2026 Undecided 80061/APP/2026/2348

72 Breakspear Rd S Ickenham UB10 8HE

Erection of a single story wrap around extension to the side and rear, erection of a front extension, conversion of roof from hip to gable end, erecti...

Hillingdon
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Frequently asked questions

When do you need planning permission for a house extension?
Single-storey rear extensions up to 4m (detached) or 3m (semi-detached / terraced) are usually permitted development. Two-storey extensions, anything in a conservation area, or larger projects almost always need a planning application.
What's the difference between planning permission and permitted development?
Permitted development rights let you build certain things without applying for planning permission, subject to specified limits. Anything outside those limits, whether taller, larger or in a protected area, needs full planning permission.
How long does a householder application take?
The statutory target is 8 weeks from validation. Most simple householder extensions are decided within that window; complex or contested cases, especially those drawing a lot of comments, can take longer.
Can I get email alerts for new extensions applications in Hillingdon?
Yes. Click "Set up alerts" on this page and you'll get a daily or weekly email listing every new extensions application published by Hillingdon. You can also narrow the alert to a postcode, street, or drawn area.

We check Hillingdon's planning portal daily. New extensions applications appear here within a day of being published.