House extensions in Gwynedd

Gwynedd received 285 householder applications in the last 12 months - about 5 a week. Rear extensions and garage works are the most common. Of the 161 decided so far, 152 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 72 applications
22 Oct 2026 In Progress C26/0632/11/DT

7 Trefonwys, Bangor, Gwynedd, LL57 2HU

Balconi arfaethedig ar y llawr cyntaf ynghyd â gwaith cysylltiedig. Proposed first floor balcony together with associated works.

Householder Planning Gwynedd
21 Oct 2026 In Progress C26/0622/40/DT

DERLWYN Lôn Caernarfon, Llwyn Hudol, Pwllheli, Gwynedd, LL53 5YE

Estyniad unllawr / Single storey extension.

Householder Planning Gwynedd
20 Oct 2026 In Progress C26/0634/44/TC

PENNANT, 10 Ralph Street, Borth Y Gest, Porthmadog, Gwynedd, LL49 9UA

Cais am Dystysgrif Datblygiad Cyfreithlon ar gyfer trosiad llofft cefn arfaethedig gyda dormer bocs cefn i greu ystafell wely gyda balconi Juliette ll...

Lawful Development Certificate Existing/Proposed Gwynedd
16 Oct 2026 In Progress C26/0592/44/CR

THE UNION INN, 7 Market Square, Tremadog, Porthmadog, Gwynedd, LL49 9RB

Dymchwel estyniadau presennol cefn a chodi estyniad unllawr newydd / Demolish existing rear extensions and erect new single storey extension

Listed Building Consent Gwynedd
16 Oct 2026 In Progress C26/0593/30/LL

DWYROS Lôn Uwchmynydd, Aberdaron, Pwllheli, Gwynedd, LL53 8BS

Trosi ac addasu adeiladau allanol presennol i ddarparu llety preswyl ategol, llety swyddfa hyblyg, cyfleuster tecawê/lluniaeth bach a champfa gysyllti...

Full Planning Gwynedd
13 Oct 2026 In Progress C26/0617/39/DT

ARWELFA Lôn Rhoslyn, Abersoch, Pwllheli, Gwynedd, LL53 7BA

Estyniadau ac newidiadau / Extension and Alterations.

Householder Planning Gwynedd
12 Oct 2026 In Progress C26/0600/44/DT

YNYS CYNGAR Ffordd Morfa Bychan, Morfa Bychan, Porthmadog, Gwynedd, LL49 9UU

Cais am adeilad allanol ategol unllawr newydd i gynnwys swyddfa gartref, campfa, storfa a garej. Bydd yr adeilad yn disodli'r garafán sefydlog bresenn...

Householder Planning Gwynedd
8 Oct 2026 In Progress C26/0509/25/DT

Y DDERWEN Lôn Rhiwlas, Waen Pentir, Bangor, Gwynedd, LL57 4EG

Dymchwel yr estyniadau unllawr presennol a'r modurdy ar wahân; adeiladu estyniadau deulawr; addasiadau i'r to presennol; gosod balconi a feranda orchu...

Householder Planning Gwynedd
7 Oct 2026 In Progress C26/0601/40/DT

MAES Y BRYN, Llwyn Hudol, Pwllheli, Gwynedd, LL53 5YF

Dymchwel dau garej bresennol a thŷ gwydr, ynghyd â chodi uchder to’r eiddo presennol ac adeiladu estyniad cefn llawr a hanner (1½ llawr), ynghyd â gar...

Householder Planning Gwynedd
6 Oct 2026 In Progress C26/0590/44/LL

THE UNION INN, 7 Market Square, Tremadog, Porthmadog, Gwynedd, LL49 9RB

Dymchwel estyniadau cefn presennol a chodi estyniad unllawr newydd / Demolish existing rear extensions and erect new single storey extension

Full Planning Gwynedd
6 Oct 2026 In Progress C26/0581/15/DT

TAN Y FFYNNON, Llanberis, Caernarfon, Gwynedd, LL55 4EL

Dymchwel modurdy a chodi adeilad gardd at ddibenion domestig. Demomolition of garage and erection of summerhouse for domestic purposes

Householder Planning Gwynedd
6 Oct 2026 In Progress C26/0471/15/TC

CRAIG Y NOS Church Lane, Llanberis, Caernarfon, Gwynedd, LL55 4TF

Cais tystysgrif cyfreithlon er mwyn cadarnhau dechreuad materol bod caniatâd ddymchwel estyniad ar gweithdy presennol ac adeiladu estyniad newydd yngh...

Lawful Development Certificate Existing/Proposed Gwynedd
5 Oct 2026 In Progress C26/0594/40/DT

GWYDDFOR, Rhosfawr, Pwllheli, Gwynedd, LL53 6YA

Adeiladu estyniadau unllawr ochr a chefn / Construction of side and rear single storey extensions

Householder Planning Gwynedd
1 Oct 2026 In Progress C26/0390/11/CR

247 High Street, Bangor, Gwynedd, LL57 1RP

Addasiadau i'r fynedfa bresennol er creu mynedfa hygyrch i bawb ac addasu'r darpariaeth i'r peiriant arian presennol / Alterations to the existing ent...

Listed Building Consent Gwynedd
1 Oct 2026 In Progress C26/0591/39/DT

BRYN HEDD, Mynytho, Pwllheli, Gwynedd, LL53 7RF

Dymchwel yr estyniad un llawr presennol i’r cefn a chodi estyniad un llawr newydd yn ei le, gyda balconi uwchben a grisiau allanol. / Proposed demolit...

Householder Planning Gwynedd
30 Sept 2026 In Progress C26/0451/15/DT

8 Blaen Y Ddôl, Llanberis, Caernarfon, Gwynedd, LL55 4TL

Codi estyniad llawr cyntaf unllawr gyda tho fflat ar ben y to fflat presennol. Erection of a first-floor flat-roof extension above the existing flat r...

Householder Planning Gwynedd
29 Sept 2026 In Progress C26/0586/17/DT

1, CHURCH COTTAGES, Llandwrog, Caernarfon, Gwynedd, LL54 5TB

Cais ar gyfer swyddfa gartref yn yr ardd gefn. Application for a home office in the rear garden.

Householder Planning Gwynedd
29 Sept 2026 In Progress C26/0192/45/LL

TOWER HOTEL YARD Stryd Y Llan, Pwllheli, Gwynedd, LL53 5RR

Trosi ac adfer yr adeiladau allanol yn ddefnydd cymysg o unedau storio, busnes ac uned byncws gyda addasaidau mewnol ac allanol i'r adeiladau / Conver...

Full Planning Gwynedd
28 Sept 2026 In Progress C26/0585/39/DT

TREE TOPS, 13 Tan Y Gaer, Abersoch, Pwllheli, Gwynedd, LL53 7LY

Amnewid balconi. Replacement balcony.

Householder Planning Gwynedd
25 Sept 2026 In Progress C26/0579/25/LL

TŶ PONT BRITANNIA Ffordd Y Parc, Parc Menai, Bangor, Gwynedd, LL57 4FD

Newidiadau allanol arfaethedig yn cynnwys ailosod ffenestri, 'curtain walling', drysau a grisiau, gosod compowndiau offer peirianyddol newydd, a mân d...

Full Planning Gwynedd
25 Sept 2026 In Progress C26/0582/00/DT

BRYN GWYNT, Llanaber, Barmouth, Gwynedd, LL42 1AZ

Estyniad unllawr / Single storey extension.

Householder Planning Gwynedd
24 Sept 2026 In Progress C26/0573/37/DT

GLANFA Beach Road, Trefor, Caernarfon, Gwynedd, LL54 5LB

Estyniad cefn deu lawr. Rear two storey extension.

Householder Planning Gwynedd
23 Sept 2026 In Progress C26/0441/11/CR

93 High Street, Bangor, Gwynedd, LL57 1NS

Addasiadau mewnol ynghyd ag ymestyn yr estyniad cefn presennol / Internal alterations together with extending the existing rear extension

Listed Building Consent Gwynedd
22 Sept 2026 In Progress C26/0541/14/CR

HEN GWRT Castle Ditch, Caernarfon, Gwynedd, LL55 2AY

Addasiadau mewnol ynghyd a gosod uned gyddwysydd ar y cefn / Internal alterations together with installing a condenser unit to the rear

Listed Building Consent Gwynedd
21 Sept 2026 In Progress C26/0568/39/DT

YNYS FAWR Lôn Engan, Abersoch, Pwllheli, Gwynedd, LL53 7LB

Codi modurdy sengl ar wahân o flaen yr annedd bresennol. Construction of detached single garage in front of existing bungalow.

Householder Planning Gwynedd
21 Sept 2026 In Progress C26/0565/39/DT

TYN Y MAES, Mynytho, Pwllheli, Gwynedd, LL53 7RL

Dymchwel garej sengl ac adeiladu garej dwbwl deulawr. Demolition of single garage and construction of double two storey garage.

Householder Planning Gwynedd
18 Sept 2026 In Progress C26/0564/35/DT

DERWEN Stanley Road, Criccieth, Gwynedd, LL52 0EH

Estyniad a newidiadau i’r sied bresennol / Extension and alterations to the existing shed.

Householder Planning Gwynedd
18 Sept 2026 In Progress C26/0534/39/LL

MYNYTHO HALL, Mynytho, Pwllheli, Gwynedd, LL53 7RF

Dymchwel adeiladau allanol a chodi estyniad deulawr a chanopi allanol wrth ymyl y prif neuadd, newid defnydd rhannol o’r ardal y tu ôl i lwyfan y brif...

Full Planning Gwynedd
17 Sept 2026 In Progress C26/0413/14/CR

14 Castle Square, Caernarfon, Gwynedd, LL55 2NF

Addasiadau mewnol ac allanol i drosi'r adeilad / Internal and external alterations to convert building

Listed Building Consent Gwynedd
16 Sept 2026 In Progress C26/0559/23/DT

LLWYNI TŶ CAPEL, Cwm Y Glo, Caernarfon, Gwynedd, LL55 4DH

Adeiladu estyniad cefn, porth blaen ac ochr newydd, gosod pwmp gwres ffynhonnell aer newydd, paneli ffotofoltaidd a storfa batri yngyd a newidiadau me...

Householder Planning Gwynedd
16 Sept 2026 In Progress C26/0535/23/DT

Isallt, 2 Tai Craig Y Don, Cwm Y Glo, LL55 4DL

Adeiladu modurdy gyda gofod gweithio llawr cyntaf Construct a garage with first floor workroom

Householder Planning Gwynedd
15 Sept 2026 In Progress C26/0529/35/LL

Plas Newydd Residential Home, PLAS NEWYDD High Street, Criccieth, Gwynedd, LL52 0RR

Addasiadau, estyniadau ac ailfodelu Cartref Gofal Plas Newydd Alterations, extensions and remodelling Plas Newydd Care Home

Full Planning Gwynedd
15 Sept 2026 In Progress C26/0551/17/CR

CAER EGLWYS, Llandwrog, Caernarfon, Gwynedd, LL54 5SY

Amnewid 9 ffenestr pren presennol a drysau dwbl gyda rhai newydd pren gydag unedau dwbl / Replace 9 existing timber windows and double doors with new ...

Listed Building Consent Gwynedd
14 Sept 2026 In Progress C26/0492/20/AC

FERN BANK, 3 Trem Y Foel, Y Felinheli, Gwynedd, LL56 4UZ

Cais i ddiwygio amod 2 (cynlluniau a gymeradwywyd) o ganiatâd cynllunio C26/0108/20/DT ar gyfer dymchwel ystafell haul presennol a chodi estyniad unll...

Removal/Variation of Condition(s) Gwynedd
14 Sept 2026 In Progress C26/0388/30/DT

BRYN MÔR Lôn Uwchmynydd, Aberdaron, Pwllheli, Gwynedd, LL53 8BS

Disodli to rhan unllawr. Ychwanegu ffenestri to i'r prif do. Ychwanegu paneli solar. Newid trefniant ffenestri. Tynnu carafán sefydlog presennol ac ad...

Householder Planning Gwynedd
11 Sept 2026 In Progress C26/0548/30/DT

YSGUBOR ISAF, Rhydlios, Pwllheli, Gwynedd, LL53 8LP

Estyniad unllawr. Single storey extension.

Householder Planning Gwynedd
11 Sept 2026 In Progress C26/0525/18/DT

RHOS AERON, Seion, Caernarfon, Gwynedd, LL55 3AL

Codi estyniad unllawr a balconi, ynghyd ag addasiadau cysylltiedig. Erection of single storey extension & balcony, along with associated alterations.

Householder Planning Gwynedd
9 Sept 2026 In Progress C26/0539/38/LL

Penrhos Polish Village, Lon Llanbedrog, Pwllheli, Gwynedd, LL53 7HN

Codi adeilad tŷ ystlumod. Erection of bat house building.

Full Planning Gwynedd
8 Sept 2026 In Progress C26/0504/11/DT

21 Orme Road, Bangor, Gwynedd, LL57 1AY

Dymchwel estyniad unllawr cefn presennol ac adeiladu estyniad deulawr cefn yn ei le. Demolish existing single storey rear extension and construct a re...

Householder Planning Gwynedd
7 Sept 2026 Approved 22 Oct C26/0536/45/DT

TŶ WINLLAN Ala Uchaf, Pwllheli, Gwynedd, LL53 5RE

Estyniad llawr cyntaf cefn arfaethedig ac addasiadau i'r gegin llawr daear / Proposed first floor rear extension and ground floor kitchen adaptations

Householder Planning Gwynedd
7 Sept 2026 In Progress C26/0519/44/CR

TŶ'R PAB, 4 Church Street, Tremadog, Porthmadog, Gwynedd, LL49 9RA

Addasiadau menwol i greu agoriad newydd yn yr eiddo drws nesaf er ymestyn y bywyty presennol ac amnewid ffenestr presennol am ddrws newydd / Internal ...

Listed Building Consent Gwynedd
3 Sept 2026 In Progress C26/0533/39/LL

GWYNFA, Mynytho, Pwllheli, Gwynedd, LL53 7RF

Sied i storio peiriannau garddio, tractor, a trelar. Shed for storing garden machinery, tractor, and trailer.

Full Planning Gwynedd
2 Sept 2026 In Progress C26/0531/32/DT

DOLAFON, Botwnnog, Pwllheli, Gwynedd, LL53 8RF

Modurdy newydd arfaethedig i ddisodli modurdy a thŷ haf presennol. Proposed new garage to replace an existing garage and summerhouse

Householder Planning Gwynedd
2 Sept 2026 In Progress C26/0532/39/DT

LAMORNA, 7 Whitehouse Drive, Abersoch, Pwllheli, Gwynedd, LL53 7AF

Estynu’r teras sydd wedi ei godi a creu ardal patio newydd / extend raised terrace and create patio area

Householder Planning Gwynedd
2 Sept 2026 Approved 23 Oct C26/0527/26/DT

10 Bryn Y Gof, Caeathro, Caernarfon, Gwynedd, LL55 2TA

Dymchwel adain gefn presennol ac adeiladu estyniad unllawr cefn yn ei le Demolish existing rear wing and erect a replacement single-storey rear extens...

Householder Planning Gwynedd
1 Sept 2026 In Progress C26/0528/30/DT

BRYN MAWR, Anelog, Pwllheli, Gwynedd, LL53 8BT

Dymchwel estyniadau presennol, adeiladu estyniad cefn ac ochr deulawr i gynnwys addasiadau. Demolition of existing extensions, construction of rear an...

Householder Planning Gwynedd
1 Sept 2026 In Progress C26/0524/00/DT

24 Marine Road, Barmouth, Gwynedd, LL42 1NS

Cais i ddymchwel estyniad unllawr presennol ac adeiladu estyniad newydd deulawr / Application to demolish existing single storey side extension and bu...

Householder Planning Gwynedd
25 Aug 2026 In Progress C26/0522/25/LL

Medical Education Centre, Ysbyty Gwynedd, Penrhosgarnedd Penrhosgarnedd, Bangor, LL57 2PW

Mae'r datblygiad arfaethedig yn cynnwys estyniad llawr cyntaf i ddarparu ardal addysgu a swyddfa ychwanegol, ynghyd â newidiadau mewnol gan gynnwys cy...

Full Planning Gwynedd
24 Aug 2026 Approved 19 Oct C26/0517/37/DT

32, CROESHIGOL TERRACE Croeshigol Road, Trefor, Caernarfon, Gwynedd, LL54 5HT

Codi porth i ddrychiad blaen y prif adeilad. Estyniad llawr cyntaf i gefn yr eiddo. / Erection of a porch to the principle elevation. First floor exte...

Householder Planning Gwynedd
21 Aug 2026 In Progress C26/0516/19/DT

PLAS Y BRYN CHALET PARK, Bontnewydd, Caernarfon, Gwynedd, LL54 7YE

Ailgyflwyno cais a wrthodwyd i godi anecs i'r prif annedd breswyl. Resubmission of a rejected application for the erection of an annex to the main res...

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

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