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Garden rooms in Wales
The short answer: Welsh rules are close to England's, with three differences worth knowing. Any part of the room within 2m of the house can be no more than 1.5m tall, a flat roof is limited to 2.5m1, and conservation areas count as protected land.2 Building regulations follow the same 15m² and 30m² rules as England.3
Planning permission in Wales
A garden room is permitted development in Wales if it meets all of these:1
- No more than 4m tall with a dual-pitched or hipped roof, 3m with a single-pitch roof, or 2.5m with a flat roof.
- The part within 2m of a boundary no more than 2.5m tall, and eaves no higher than 2.5m.
- The part within 2m of the house no more than 1.5m tall. This rule is unique to Wales.
- Not in front of the house, one storey only, and no raised platform over 300mm.
- Together with other buildings, covering no more than half the garden.
Flats and maisonettes don't get these rights, and nothing can be built in the grounds of a listed building without permission.1 Where a side wall faces a road, the room can't come nearer the road than that wall, or than 5m from the road, whichever is nearer the road.1
Protected land in Wales
In Wales, conservation areas count as protected land alongside national parks, Areas of Outstanding Natural Beauty and World Heritage Sites. On all of them, you can't build to the side of the house, and buildings more than 20m from the house can cover no more than 10m² in total.2 That's stricter than England, where the 10m² rule doesn't apply in conservation areas.
- National parks: Snowdonia (Eryri), Pembrokeshire Coast and the Brecon Beacons (Bannau Brycheiniog).4
- Areas of Outstanding Natural Beauty: Anglesey, Clwydian Range and Dee Valley, Llŷn Peninsula, Gower and Wye Valley.4
- World Heritage Sites: the castles and town walls of Gwynedd, Blaenavon, Pontcysyllte Aqueduct and Canal, and the slate landscape of north-west Wales.5
Building regulations and electrics
Under 15m² with no sleeping accommodation, building regulations don't normally apply. From 15m² to 30m² they don't normally apply either, as long as nobody sleeps in it and it's at least 1m from every boundary or built mostly of non-combustible materials.3
Electrics are a little stricter than in England. Welsh guidance says any new electrical work in the garden, or that crosses the garden, is notifiable, not just a new circuit.6 So the supply to your garden room must be done by a registered electrician who can certify it, or notified to building control before work starts.
Who to ask
Wales has 25 planning authorities: 22 councils and the 3 national park authorities.7 Since 1 December 2025 a planning application for an outbuilding costs £283, and a lawful development certificate, which confirms in writing that you don't need permission, costs half that.8
What a garden room costs in Wales
We haven't found a reliable Wales-only price guide. Installed garden rooms typically cost £1,200 to £2,500 per m² across the UK9, so a 4m x 3m room usually costs £14,400 to £30,000 before extras such as the base and electrics.
Want this checked for your own garden? Get a free planning report: we look up protected land at your postcode and apply the rules to your plans.
Get my free reportQuestions people ask
Do I need planning permission for a garden room in Wales?
Usually not, if it's behind the house and within the height limits: 4m with a dual-pitched roof, 3m with a single pitch, 2.5m with a flat roof, 2.5m for any part within 2m of a boundary, and 1.5m for any part within 2m of the house.
What is different about garden rooms in Wales?
Three things: the 1.5m limit within 2m of the house, the 2.5m limit for flat roofs, and conservation areas counting as protected land for the 10m² rule. Electrical rules for garden work are also slightly stricter.
How much is a lawful development certificate in Wales?
Half the planning fee for the work. For an outbuilding, the planning fee has been £283 since December 2025.
Related guides
Other areasRules and costs in other parts of the UK.
Free planning reportCheck protected land at your postcode.
Garden room costsReal prices by size, with a calculator.
Sources
- Welsh Government, Planning permission: outbuildings.
- Welsh Government, Permitted development for householders: technical guidance.
- Welsh Government, Building regulations: outbuildings.
- Law Wales, Protected landscapes.
- Cadw, World Heritage Sites in Wales.
- Welsh Government, Approved Document P: electrical safety (Wales). New electrical work in a garden is notifiable.
- Planning Portal, Local planning authorities: a focus on Wales.
- Welsh Government, Planning application fees, fees from 1 December 2025.
- MyBuilder, Garden room cost price guide, updated 21 October 2026. UK price ranges for garden rooms, foundations, electrics, plumbing and fees.