House extensions in Cardiff

Cardiff received 860 householder applications in the last 12 months - about 17 a week. Rear extensions and dormers are the most common. Of the 643 decided so far, 604 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 205 applications
20 Oct 2026 Registered 26/02204/FUL

Southgate House Wood Street Cathays Cardiff

New Entrance Doors

Full Planning Permission Cardiff
19 Oct 2026 Registered 26/02201/HSE

11 Clos Y Bryn Rhiwbina Cardiff CF14 6TR

Proposed single and two storey rear extensions, full height front extension and a contemporary transformation of the existing building. Alterations to...

Householder Planning Permission Cardiff
19 Oct 2026 Registered 26/02202/HSE

577 Cowbridge Road East Canton Cardiff CF5 1BE

Single storey rear extension.

Householder Planning Permission Cardiff
19 Oct 2026 Registered 26/02199/HSE

66 Heol Cynwrig Fairwater Cardiff CF5 2DB

Proposed two storey side extension

Householder Planning Permission Cardiff
16 Oct 2026 Registered 26/02181/NMA

10 Boverton Street Roath Cardiff CF23 5ES

Propoed Non-Material Amendment to Planning Permission 25/02102/HSE - To increase eave height of rear extension and addition of 2 velux roof windows

Non Material Amendment Cardiff
16 Oct 2026 Registered 26/02185/HSE

36 Bronllwyn Pentyrch Cardiff CF15 9QL

Proposed conversion of attached garage, changing tiled roof to flat roof and installation of patio doors

Householder Planning Permission Cardiff
15 Oct 2026 Registered 26/02188/FUL

62 Llantrisant Street Cathays Cardiff CF24 4JE

Conversion of Class C4 HMO to large sui generis house with dormer loft conversion

Full Planning Permission Cardiff
15 Oct 2026 Registered 26/02191/FUL

1 Senghennydd Place Cathays Cardiff CF24 4AF

Erection of a side/rear extension to an existing Class C4 HMO for the addition of two bedrooms, resulting in a total of six bedrooms.

Full Planning Permission Cardiff
15 Oct 2026 Registered 26/02170/CLPUD

3 Cefn Coed Crescent Cyncoed Cardiff CF23 6AT

Proposed first floor extension over existing single storey room.

Cert of Lawfulness Proposed (s192) Cardiff
15 Oct 2026 Registered 26/02171/HSE

216 Cyncoed Road Cyncoed Cardiff CF23 6RS

Proposed single storey extension to the south west of the existing dwelling and new door in the north west elevation.

Householder Planning Permission Cardiff
14 Oct 2026 Registered 26/02166/HSE

28 Garth Olwg Gwaelod-y-garth Cardiff CF15 9HW

Proposed rear apex dormer and installation of two roof windows

Householder Planning Permission Cardiff
14 Oct 2026 Registered 26/01976/FUL

Rear Of 50 Walker Road Splott Cardiff CF24 2EN

Convert existing single storey garage into one Bedroom accommodation with pitched roof.

Full Planning Permission Cardiff
14 Oct 2026 Registered 26/02169/CLPUD

13 Maes Y Briallu Morganstown Cardiff CF15 8FA

Proposed single storey side extension to existing house.

Cert of Lawfulness Proposed (s192) Cardiff
14 Oct 2026 Registered 26/02165/FUL

110 Maindy Road Cathays Cardiff CF24 4HQ

Change of Use from Single Dwelling house, to a Six-Bedroom HMO. Erection of a Two-Storey Rear Extension, Rear Dormer Roof Extension and Installation o...

Full Planning Permission Cardiff
13 Oct 2026 Registered 26/02160/HSE

35 Meyrick Road Ely Cardiff CF5 4RN

Proposed Single Storey Side Extension

Householder Planning Permission Cardiff
12 Oct 2026 Registered 26/02216/WTTPP

Lisvane & Llanishen Reservoirs Visitor Centre Lisvane Road Llanishen Cardiff CF14 0SD

TPO woodland 696/W01 Lisvane & Llanishen reservoirs - remedial works for health and safety purposes to trees T9, T12, T13, T14 and T15 as per submitte...

Works to Trees Prune Trees in TPO Cardiff
12 Oct 2026 Registered 26/02148/LBC

Rose Cottage Crofft-y-genau Road St Fagans Cardiff CF5 6DU

Retrospective application for conservation roof light with lead flashing kit within exiting roof and alterations to internal modern plasterboard parti...

Listed Building Consent Cardiff
12 Oct 2026 Registered 26/02147/HSE

Rose Cottage Crofft-y-genau Road St Fagans Cardiff CF5 6DU

Retrospective application for conservation roof light with lead flashing kit within exiting roof and alterations to internal modern plasterboard parti...

Householder Planning Permission Cardiff
12 Oct 2026 Registered 26/02146/HSE

5 Heol Dyfed Heath Cardiff CF14 4PN

Erection of a double storey side extension with solar panels on the existing & proposed roof

Householder Planning Permission Cardiff
12 Oct 2026 Registered 26/02014/FUL

1 And 3 Soberton Avenue And Land To The Rear Gabalfa Cardiff CF14 3NJ

Conversion from 4 to 9 flats with ground floor rear and side extensions, first floor rear extensions and rear dormer loft conversions. Demolition of r...

Full Planning Permission Cardiff
9 Oct 2026 Registered 26/02187/HSE

33 Groveland Road Heath Cardiff CF14 4QX

Ground floor rear extension.

Householder Planning Permission Cardiff
9 Oct 2026 Registered 26/02186/HSE

22 Handley Road Splott Cardiff CF24 2HF

Garage conversion with rear extension.

Householder Planning Permission Cardiff
9 Oct 2026 Registered 26/02133/LBC

7 - 8 Bute Crescent Butetown Cardiff CF10 5AN

Internal and external refurbishment of the existing Eli Jenkins public house

Listed Building Consent Cardiff
9 Oct 2026 Registered 26/02127/FUL

287 Cyncoed Road Cyncoed Cardiff CF23 6PA

Proposed Erection Of A Front Pergola With Retractable Roof Within The Front External Area

Full Planning Permission Cardiff
9 Oct 2026 Registered 26/02126/HSE

47 Egremont Road Penylan Cardiff CF23 5LP

Demolition of existing single storey side extension and the construction of a two storey side extension in lieu

Householder Planning Permission Cardiff
7 Oct 2026 Registered 26/02116/LBC

The Cathedral School Cardiff Road Llandaff Cardiff CF5 2YH

4 storey extension (including undercroft) to existing building to expand dining provision, create additional teaching spaces and improve ancillary acc...

Listed Building Consent Cardiff
7 Oct 2026 Registered 26/02115/FUL

The Cathedral School Cardiff Road Llandaff Cardiff CF5 2YH

4 storey extension (including undercroft) to existing building to expand dining provision, create additional teaching spaces and improve ancillary acc...

Full Planning Permission Cardiff
7 Oct 2026 Registered 26/02152/FUL

70 May Street Cathays Cardiff CF24 4EY

Ground floor rear extension, rear dormer extension and change of use from class C4 House in Multiple Occupation (HMO) to large Sui Generis house.

Full Planning Permission Cardiff
7 Oct 2026 Registered 26/02093/HSE

122 Court Road Grangetown Cardiff CF11 6SE

Repair and increase in height of existing boundary wall and installation of a roller shutter at existing access opening within the wall, replacing pre...

Householder Planning Permission Cardiff
7 Oct 2026 Registered 26/02117/CLPUD

27 Woodfield Avenue Radyr Cardiff CF15 8EF

Proposed single storey side extension to this semi-detached property

Cert of Lawfulness Proposed (s192) Cardiff
7 Oct 2026 Registered 26/02113/HSE

78 Mill Road Lisvane Cardiff CF14 0UG

Proposed first floor extension at side of house

Householder Planning Permission Cardiff
7 Oct 2026 Registered 26/02112/HSE

7 Penydarren Drive Whitchurch Cardiff CF14 2TT

Proposed Single Storey Side/Rear Extension with Garage Conversion

Householder Planning Permission Cardiff
6 Oct 2026 Registered 26/02104/HSE

15 Brynteg Rhiwbina Cardiff CF14 6TS

Proposed single storey rear extension to the existing semi-detached dwelling including minor internal and external modifications

Householder Planning Permission Cardiff
6 Oct 2026 Registered 26/02102/HSE

49 Kimberley Road Penylan Cardiff CF23 5DL

Proposed ground floor rear side return extension

Householder Planning Permission Cardiff
5 Oct 2026 Registered 26/02097/HSE

52 Clonakilty Way Pontprennau Cardiff CF23 8PS

Proposed side single and double storey extension, including a small rear single storey extension attached.

Householder Planning Permission Cardiff
5 Oct 2026 Registered 26/02098/HSE

14 Taff Terrace Grangetown Cardiff CF11 7AL

Proposed single storey rear extension

Householder Planning Permission Cardiff
5 Oct 2026 Registered 26/01899/HSE

19 Wordsworth Avenue Roath Cardiff CF24 3FQ

Replacement of roof for one storey extension to rear of property and replacement of roof for one storey garage outbuilding.

Householder Planning Permission Cardiff
5 Oct 2026 Registered 26/02100/HSE

5 Celyn Grove Cyncoed Cardiff CF23 6SH

Proposed first floor extension to the rear, including minor internal modifications

Householder Planning Permission Cardiff
5 Oct 2026 Registered 26/02096/HSE

8 Deganwy Close Llanishen Cardiff CF14 5JT

Porch extension.

Householder Planning Permission Cardiff
5 Oct 2026 Registered 26/02094/FUL

29 Cranbrook Street Cathays Cardiff CF24 4AL

Proposed construction of a dormer loft conversion and Change of Use from a Dwellinghouse (Use Class C3) to House in Multiple Occupation (Use Class C4)...

Full Planning Permission Cardiff
5 Oct 2026 Registered 26/02092/LBC

Shah Jalal Islamic Cultural Centre Crwys Road Roath Cardiff CF24 4NA

Proposed installation of a wooden and glass panel to protect the porch from rain and weather

Listed Building Consent Cardiff
2 Oct 2026 Registered 26/02090/HSE

104 Heol Hir Llanishen Cardiff CF14 5AD

Proposed single storey rear extension, small double height extension and attic conversion including roof extensions

Householder Planning Permission Cardiff
2 Oct 2026 Registered 26/02089/HSE

72 Amesbury Road Penylan Cardiff CF23 5DY

Proposed Loft & Rebuild of Existing Extension

Householder Planning Permission Cardiff
2 Oct 2026 Awaiting decision 26/02084/CLPUD

24 Bassetts Field Rhiwbina Cardiff CF14 9UG

Proposed single storey flat roof extension to rear

Cert of Lawfulness Proposed (s192) Cardiff
1 Oct 2026 Registered 26/02138/HSE

44 Treherbert Street Cathays Cardiff CF24 4JN

Ground and first floor rear extension and dormer loft conversion.

Householder Planning Permission Cardiff
1 Oct 2026 Registered 26/02072/HSE

18 Heol Caerhys Rhiwbina Cardiff CF14 6AN

Demolition of existing single story garage to the side of the property. Demolition of existing single story extension and conservatory to the rear of ...

Householder Planning Permission Cardiff
1 Oct 2026 Registered 26/02073/HSE

122 Parc-y-fro Creigiau Cardiff CF15 9SB

Proposed two storey side extension & front porch canopy

Householder Planning Permission Cardiff
30 Sept 2026 Registered 26/02070/HSE

43 Dalton Street Cathays Cardiff CF24 4HB

Retention of Existing Rear and Side Ground-Floor Extensions and Proposed Erection of Rear and Side Dormer Extensions.

Householder Planning Permission Cardiff
30 Sept 2026 Registered 26/02028/HSE

67 St Ina Road Heath Cardiff CF14 4LT

Demolition of existing garage, erection of single storey rear and side extension

Householder Planning Permission Cardiff
30 Sept 2026 Registered 26/02068/HSE

38 Major Road Canton Cardiff CF5 1PF

Single-storey rear extension

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.