In England, garden decking does not need planning permission if no part is more than 30cm above the ground, none is in front of the house, and with extensions and outbuildings it covers no more than half the garden. A higher deck, a front-garden deck, or any deck at a flat or listed building needs permission.
The rules below come from the government's permitted development technical guidance and the Planning Portal. They apply to houses in England. This is general information, not legal advice, and your council has the final say on any particular deck.
Where the 30cm rule comes from
Garden decking falls under Class E of the householder permitted development rights, the class that also covers sheds and other garden buildings. The government's technical guidance says Class E "allows garden decking provided it is not more than 0.3 metres high", subject to the other limits in that class.
The same guidance defines a raised platform as any platform with a height of more than 0.3 metres, and says verandahs, balconies and raised platforms are not permitted development. So a deck that goes over 30cm stops being ordinary decking in planning terms and becomes a raised platform, which needs a planning application.
The Planning Portal sets out the conditions in plain terms: the deck must be no more than 30cm above the ground, it must not cover more than 50% of the garden together with other extensions and outbuildings, and none of it can sit forward of the wall forming the principal elevation of the house.
How is the 30cm measured?
Height is measured from ground level. The technical guidance defines ground level as the surface of the ground immediately next to the structure, and says it does not include anything laid on top of the ground, such as decking. In practice that means measuring from the ground beside the deck up to the surface you walk on. Height is the whole platform, frame and boards together.
What if my garden slopes?
This is where most questions come from. On a sloping garden, a deck that is level with the back door can be 10cm off the ground at the house end and 60cm off the ground at the far end.
The technical guidance says that where ground level is not uniform, for example on a slope, ground level is "the highest part of the surface of the ground next to the building". It does not set out a separate method for decks, and the Planning Portal simply says the decking must be "no more than 30cm above the ground". Because of that, the cautious reading is that every part of the deck should be within 30cm of the ground beneath it.
If your deck would go over 30cm at the low end, you have three practical options:
- Step it down. Two or three levels, each kept within 30cm of the ground under it, can follow the slope.
- Apply for planning permission. The council will consider the effect on the neighbours, including how much the deck overlooks them.
- Ask the council first. A lawful development certificate confirms in writing that a proposed deck is permitted development (see the FAQ below).
A local specialist can measure the fall across the garden and tell you where a level deck would cross 30cm, before you commit to a design.
Does decking count towards the 50% garden limit?
Yes. Under Class E, the total ground covered by buildings, enclosures and containers around the house, other than the original house itself, must not exceed 50% of the curtilage. The Planning Portal applies the same 50% limit to decking combined with other extensions and outbuildings.
The technical guidance says the limit includes existing and proposed extensions, and detached buildings such as garages and sheds even if they were built before 1948. The original house means the house as it was first built, or as it stood on 1 July 1948 if it was built before then. The curtilage is the land that forms part and parcel of the house, which for most homes is the garden.
As a worked example: if the land around the house is 120m², the limit is 60m². A 15m² rear extension, a 6m² shed and an 18m² detached garage already use 39m², which leaves 21m² for decking before you would need permission.
Can decking go in a front garden?
Not under permitted development. Class E does not allow anything forward of the wall forming the principal elevation of the original house, which in most cases is the side of the house facing the main road serving it. The guidance extends this to anything in front of a line drawn from the principal elevation to the side boundary. A deck in a front garden therefore needs planning permission, whatever its height.
Conservation areas, listed buildings and protected landscapes
Conservation areas, National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites are "Article 2(3) land". There, Class E does not allow decking on land between a side wall of the house and the boundary, so a deck down the side of the house needs permission. The 30cm and 50% rules still apply at the back.
In National Parks, the Broads, Areas of Outstanding Natural Beauty and World Heritage Sites, the total area of buildings and decking more than 20m from the house is also limited to 10m².
Listed buildings are stricter. The Planning Portal says that within the curtilage of a listed building, no decking or platform is permitted development, so any deck needs a planning application. Ask the council's conservation officer at the same time whether listed building consent is also needed.
Flats, maisonettes and newer estates
The decking allowance applies to houses only. The Planning Portal says it does not apply to flats or maisonettes, converted houses, houses created under certain permitted development rights for new homes, or areas where a planning condition or an Article 4 direction has removed the right. Many estates built in recent decades have a condition removing permitted development rights, so check the original planning permission for the house, which the council can provide.
If a deck sits within all the limits, a local specialist can price it from photos. Raised and multi-level decks are covered on the decking service page, and the decking cost guide shows what the extra height adds to the price. A raised deck near a boundary can overlook next door, so a privacy screen is worth considering; check how high a fence can be first.
Questions
Does decking need building regulations approval?
The Planning Portal says building regulations should be assumed to apply to any deck that needs planning permission, and suggests contacting your local building control body if you are unsure. Whatever the paperwork, ask the specialist how the frame, posts and any steps or handrails will be built.
Does a balcony or roof terrace count as decking?
No. The technical guidance treats a roof terrace as a raised platform, and says verandahs, balconies and raised platforms are not permitted development. Any of them needs a planning application, even if it is small.
Can I get written proof that my deck does not need permission?
Yes. You can apply to the council for a lawful development certificate for a proposed development, which confirms that what you plan is permitted development. The Planning Portal puts the fee at half the normal planning fee. It is optional, but useful on a sloping site or when you come to sell.
What happens if my deck was built without the permission it needed?
The council can serve an enforcement notice requiring the work to be undone, which you can appeal. Planning law also allows permission to be granted for work already carried out, so the usual first step is a retrospective planning application. Lowering or stepping the deck to within 30cm is often the simpler fix.