House extensions in Cardiff

Cardiff received 690 householder applications in the last 12 months - about 13 a week. Rear extensions and dormers are the most common. Of the 492 decided so far, 462 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 219 applications
2 days ago Registered 26/01908/FUL

9 St Peter's Street Roath Cardiff CF24 3BA

Demolition of existing two storey side extension and replacement with new remodelled two storey extension

Full Planning Permission Cardiff
2 days ago Registered 26/01907/HSE

46 Oakley Place Grangetown Cardiff CF11 7EW

Rear dormer roof extension.

Householder Planning Permission Cardiff
9 Sept 2026 Registered 26/01905/HSE

9 Clos William Rhiwbina Cardiff CF14 6QJ

Single Storey Side/Rear Extension with Internal Alterations. Loft Reconfiguration with Dormers. Detached Garage Enlargement.

Householder Planning Permission Cardiff
9 Sept 2026 Pending 26/01888/HSE

26 Garrick Drive Thornhill Cardiff CF14 9BG

Single storey side extension.

Householder Planning Permission Cardiff
9 Sept 2026 Pending 26/01892/HSE

86 Waterloo Road Penylan Cardiff CF23 9BH

Demolition of existing rear conservatory and part rear ground floor. Construction of single storey rear extension.

Householder Planning Permission Cardiff
8 Sept 2026 Pending 26/01151/FUL

The Meadows (Formerly Blair Athol) Lisvane Road Llanishen Cardiff CF14 0SE

Garden room and revised landscape plan.

Full Planning Permission Cardiff
8 Sept 2026 Pending 26/01887/FUL

276 North Road Gabalfa Cardiff CF14 3BL

Conversion first and second floors from one flat to two with roof lights added.

Full Planning Permission Cardiff
8 Sept 2026 Pending 26/01883/CLPUD

Heathfield 135 Pantbach Road Heath Cardiff CF14 1TY

Proposed enlargement of the existing single-storey rear extension and removal of the existing flat roof and construction of a pitched roof over the en...

Cert of Lawfulness Proposed (s192) Cardiff
8 Sept 2026 Pending 26/01882/HSE

58 Llantarnam Road Mynachdy Cardiff CF14 3EG

Proposed erection of a part single-storey, part two-storey rear extension with associated external alterations.

Householder Planning Permission Cardiff
7 Sept 2026 Pending 26/01880/HSE

40 Severn Road Pontcanna Cardiff CF11 9EB

Proposed erection of a single-storey bay window to the front elevation in place of the existing ground floor window, and associated external works.

Householder Planning Permission Cardiff
7 Sept 2026 Pending 26/01871/HSE

18 Clos Parc Radur Radyr Cardiff CF15 8GH

Single storey rear extension.

Householder Planning Permission Cardiff
7 Sept 2026 Pending 26/01873/HSE

135 Whitchurch Road Gabalfa Cardiff CF14 3JQ

2 storey rear extension and dormer loft conversion

Householder Planning Permission Cardiff
7 Sept 2026 Pending 26/01878/FUL

St Julians Forge Bridge Road Old St Mellons Cardiff CF3 6YJ

Proposed conversion and extensions of existing annex to form a dwelling house & erection of a detached bungalow

Full Planning Permission Cardiff
4 Sept 2026 Pending 26/01836/HSE

14 Trem Y Rhyd St Fagans Cardiff CF5 6FW

Single storey rear extension and conversion of existing garage.

Householder Planning Permission Cardiff
4 Sept 2026 Pending 26/01858/HSE

150 Western Avenue North Llandaff North Cardiff CF14 2SD

Single storey rear extension.

Householder Planning Permission Cardiff
4 Sept 2026 Pending 26/01739/CLPUD

48 Hendre Road Trowbridge Cardiff CF3 1QW

Proposed single-storey rear extension with internal ground floor layout alteration

Cert of Lawfulness Proposed (s192) Cardiff
3 Sept 2026 Pending 26/01847/HSE

19 Grange Place Grangetown Cardiff CF11 7DB

Single storey granny annexe.

Householder Planning Permission Cardiff
3 Sept 2026 Pending 26/01860/CLPUD

15 Hill-snook Road Ely Cardiff CF5 5DD

Proposed loft conversion with flat roof rear Dormer addition of rooflights to the front

Cert of Lawfulness Proposed (s192) Cardiff
3 Sept 2026 Pending 26/01855/CLPUD

46 Duffryn Avenue Cyncoed Cardiff CF23 6JL

Proposed hip to gable loft conversion

Cert of Lawfulness Proposed (s192) Cardiff
3 Sept 2026 Pending 26/01861/FUL

166 - 168 Cathedral Road Pontcanna Cardiff CF11 9JD

Proposed rear extensions at ground and first floor, extension to rear roof dormers, external alterations, re-roofing and making good of host property ...

Full Planning Permission Cardiff
2 Sept 2026 Pending 26/01762/FUL

2 Gwennyth Street Cathays Cardiff CF24 4PH

Side extension to create three flats.

Full Planning Permission Cardiff
1 Sept 2026 Pending 26/01816/HSE

36 Plasturton Gardens Pontcanna Cardiff CF11 9HF

Demolition of rear garage and outhouse, construction of gated boundary wall and other external works.

Householder Planning Permission Cardiff
1 Sept 2026 Pending 26/01841/HSE

160 Heol Llanishen Fach Rhiwbina Cardiff CF14 6RG

Two storey side extension and loft conversion with front and rear dormers

Householder Planning Permission Cardiff
31 Aug 2026 Pending 26/01839/FUL

56 Crwys Road Cathays Cardiff CF24 4NN

First floor rear extension, rear dormer loft conversion and conversion of upper floors to 2 flats

Full Planning Permission Cardiff
31 Aug 2026 Pending 26/01834/HSE

2 Pitman Street Pontcanna Cardiff CF11 9DJ

Proposed construction of a new dormer window to the rear elevation roof, install 2 roof windows to the front elevation roof and fix 8 PV Panels to the...

Householder Planning Permission Cardiff
31 Aug 2026 Pending 26/01835/HSE

35 Chamberlain Road Llandaff North Cardiff CF14 2LW

Demolition of existing garage and erection of 2 storey side extension and alterations.

Householder Planning Permission Cardiff
28 Aug 2026 Registered 26/01833/HSE

66 Windermere Avenue Cyncoed Cardiff CF23 5PS

Proposed single-storey rear extension. Conversion of the roof space. Associated internal alterations and a new patio to the rear garden.

Householder Planning Permission Cardiff
28 Aug 2026 Pending 26/01830/HSE

3 Ash Tree Close Radyr Cardiff CF15 8RX

Proposed demolition of existing side garage and replacement with single storey side extension

Householder Planning Permission Cardiff
27 Aug 2026 Approved 26/01648/CLPUD

76 Church Road Rumney Cardiff CF3 3BB

Conversion of the existing roof space into habitable accommodation.

Cert of Lawfulness Proposed (s192) Cardiff
26 Aug 2026 Registered 26/01809/HSE

13 Pencisely Rise Canton Cardiff CF5 1DX

Single storey rear extension.

Householder Planning Permission Cardiff
26 Aug 2026 Pending 26/01818/HSE

82 Heol-y-deri Rhiwbina Cardiff CF14 6HJ

Loft extension with roof alterations, front porch and associated works.

Householder Planning Permission Cardiff
25 Aug 2026 Refused 26/01807/CLPUD

33 Blossom Drive Lisvane Cardiff CF14 0BE

Proposed single storey rear extension and conversion of integral garage

Cert of Lawfulness Proposed (s192) Cardiff
24 Aug 2026 Registered 26/01796/HSE

6 Windsor Esplanade Butetown Cardiff CF10 5BG

Widening of the existing single car garage and the fitment of a new flat roof.

Householder Planning Permission Cardiff
24 Aug 2026 Registered 26/01803/FUL

Pinetree Court 904 Newport Road Rumney Cardiff CF3 4LL

Proposed external alterations to 'Juniper Studio' building

Full Planning Permission Cardiff
24 Aug 2026 Registered 26/01795/HSE

6 Windsor Esplanade Butetown Cardiff CF10 5BG

Widen the existing single vehicle garage and install a new, flat roof.

Householder Planning Permission Cardiff
24 Aug 2026 Registered 26/01804/LBC

St Fagans Castle Crofft-y-genau Road St Fagans Cardiff

Repair and partial rebuilding of a chimney and repair to window to one of the Castle`s rear outbuildings

Listed Building Consent Cardiff
24 Aug 2026 Registered 26/01793/HSE

9 Tymawr Close Rumney Cardiff CF3 3BU

Proposed two storey side and rear extension, single storey rear extension, alterations to roof including attic conversion and rear dormer

Householder Planning Permission Cardiff
24 Aug 2026 Registered 26/01792/HSE

33 Tydfil Place Roath Cardiff CF23 5HP

Proposed rear flat roof garage

Householder Planning Permission Cardiff
24 Aug 2026 Registered 26/01794/FUL

116 King's Road Pontcanna Cardiff CF11 9DG

Rear dormer roof extension and rear kitchen side extension

Full Planning Permission Cardiff
21 Aug 2026 Registered 26/01635/HSE

3 Heol-y-pentre Pentyrch Cardiff CF15 9QD

Single storey side and rear extensions, single storey front outbuilding and alteratins to parking bay.

Householder Planning Permission Cardiff
21 Aug 2026 Registered 26/01791/HSE

27 Highfields Llandaff Cardiff CF5 2QB

Proposed two storey side extension

Householder Planning Permission Cardiff
21 Aug 2026 Registered 26/01785/HSE

9 The Paddock Lisvane Cardiff CF14 0AY

Single storey and partial two storey rear extensions.

Householder Planning Permission Cardiff
21 Aug 2026 Registered 26/01783/HSE

18 Heol Y Gors Whitchurch Cardiff CF14 1HF

Proposed 2 storey side extension and single storey rear extension with internal alterations

Householder Planning Permission Cardiff
21 Aug 2026 Registered 26/01781/FUL

Hafandawel Main Road Gwaelod-y-garth Cardiff CF15 9HJ

Proposed erection of detached cabin in rear garden

Full Planning Permission Cardiff
20 Aug 2026 Registered 26/01776/HSE

53 Plas Y Delyn Lisvane Cardiff CF14 0SS

Ground floor rear extension and extended patio

Householder Planning Permission Cardiff
19 Aug 2026 Approved 26/01759/CLPUD

5 Llandennis Green Cyncoed Cardiff CF23 6JX

Proposed rear single storey extension

Cert of Lawfulness Proposed (s192) Cardiff
19 Aug 2026 Registered 26/01761/FUL

Castell Coch Farm Mill Road Tongwynlais Cardiff CF15 7JQ

Proposed subdivision of existing dwelling to create two self-contained dwellings; with associated internal reconfiguration, garage extension and alter...

Full Planning Permission Cardiff
19 Aug 2026 Registered 26/01768/HSE

131 Maindy Road Cathays Cardiff CF24 4HN

Proposed erection of a detached single-storey garage in the rear garden

Householder Planning Permission Cardiff
19 Aug 2026 Registered 26/01763/HSE

7 Welby Road Canton Cardiff CF5 1PA

Ground floor rear/side extension and rear dormer loft conversion

Householder Planning Permission Cardiff
18 Aug 2026 Registered 26/01751/HSE

21 Kyle Crescent Heath Cardiff CF14 1ST

Proposed Rear Dormer Extension with Front Rooflight, Installation of Velux Rooflights to the Existing Single-Storey Extension, and Associated External...

Householder Planning Permission Cardiff
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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 Cardiff?
Yes. Click "Set up alerts" on this page and you'll get a daily or weekly email listing every new extensions application published by Cardiff. You can also narrow the alert to a postcode, street, or drawn area.

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