Do You Need Planning Permission for Composite Decking?

For most gardens, you do not need planning permission for composite decking. In England, decking is permitted development as long as it sits no more than 300mm above the ground below it, covers no more than 50% of your garden when added to other buildings, and is not built in front of your house. Go higher than 300mm and it counts as a raised platform, which does need permission. The rules are about the deck itself, not the material, so composite is treated exactly the same as timber. If you are in a conservation area, a listed building or a flat, always check with your local council first.

It is one of the first things worth checking before you build, because getting it wrong can mean taking a finished deck back down. The good news is that most garden decks do not need permission at all. Here is when you need planning permission for composite decking in the UK, the three rules that decide it, and the situations where you should pick up the phone to your council first. One thing up front: this is general guidance, not planning advice, so always confirm your own situation with your local planning authority.

Do you need planning permission for composite decking?

For the majority of homeowners, no. Garden decking is classed as permitted development in England, which means you can build it without a planning application, as long as it stays within three limits. It is worth saying that planning rules do not care whether your deck is composite or timber, they care about the deck, so composite decking is treated exactly the same as any other decking. Here are the three things that keep you inside permitted development.

The three rules that keep you permitted

Meet all three and you are almost certainly fine to build. Miss any one of them and you will likely need to apply. The height is measured from the natural ground directly under each point of the deck to the top of the boards, and the 50% figure is cumulative, so sheds, garages and extensions all count towards it.

When 300mm is easy to breach without realising

The height rule catches people out, because it is measured from the ground under the deck, not from your back door. A garden that slopes away from the house means the far edge of the deck can be well over 300mm even if the deck itself looks level. Building a raised frame to level off a bumpy garden does the same. And if you add steps or a second level, those raised parts count too. If any part of the deck goes over 300mm, the whole thing is treated as a raised platform and needs permission.

When you will need planning permission

Some situations need planning permission for composite decking whatever the height:

• The deck is more than 300mm above the ground at any point
• It would cover more than half the garden, counting other buildings
• It sits forward of the front of your house
• Your home is a flat or maisonette, as permitted development is for houses
• You are in a conservation area, National Park or Area of Outstanding Natural Beauty, or your council has an Article 4 direction
• Your home is listed, as decking within the curtilage of a listed building is not permitted

In any of these, or if you are simply not sure, a quick call to your local planning authority settles it before you spend any money.

What about building regulations?

Separate from planning, there are building regulations. Straightforward, low garden decking generally does not need building regs approval. They come into play mainly when a deck is raised. Where there is a drop of more than 600mm you need guarding at least 1100mm high with no gap a small child could slip through, and a deck attached to the house can affect things like fire escape. If your deck is low and freestanding this usually will not apply, but building control at your council can confirm.

The safe approach

Planning is far cheaper to sort before you build than after. If your deck is low, behind the house and not eating your whole garden, you are very likely permitted and good to go. If it is raised, prominent, or your property has any protected status, check first. These rules apply in England and Wales is broadly the same, but Scotland and Northern Ireland have their own rules, so check locally if you are there. And remember this is general guidance, the final word always rests with your local planning authority.

Once you know where you stand, we can help with the deck itself. See the full range on our composite decking boards page, order a free sample pack, or read our composite decking cost guide to budget the job.