What are the permitted development rules for decking?

Permitted development is what lets most homeowners build low decking without a planning application. The rules come down to two numbers and a list of exceptions — here is exactly how they work.

The two main permitted development tests

Under permitted development, the Planning Portal allows garden decking without a planning application provided it satisfies both of these tests:

• The height test: the decking platform must be no more than 30cm above the natural ground level. This is the most important figure to get right.
• The coverage test: the decking, together with any other buildings, extensions and outbuildings, must not cover more than 50% of the total area of land around the original house. The original house means the dwelling as it was first built, or as it stood on 1 July 1948, so earlier extensions reduce what you have left.

Both tests must be satisfied at the same time. A deck that is low enough but breaches the 50% coverage limit is not permitted development, and neither is a deck within the coverage limit that stands higher than 30cm.

Indicative summary of the main permitted development tests for decking in England. Source: Planning Portal (gov.uk). Rules differ in Scotland, Wales and Northern Ireland.

Where permitted development rights are removed or restricted

Permitted development is not universal. The rights are reduced, restricted or removed entirely in several situations:

• Listed buildings: permitted development rights generally do not apply, and you should assume planning permission — and possibly listed building consent — is needed even for ground-level decking.
• Conservation areas: rights are tighter, so confirm with your council before building.
• National Parks, the Broads and Areas of Outstanding Natural Beauty: these 'designated areas' carry restricted permitted development, so check first.
• Article 4 directions: some councils remove permitted development rights from particular streets or areas through an Article 4 direction, which means you must apply even where you otherwise would not.
• Flats and maisonettes: permitted development rights for this kind of work apply to houses, not flats, so decking on a flat usually needs permission.

How the height and coverage limits are measured

The 30cm height limit is measured from the natural ground level beneath the deck up to the top of the decking surface. On flat ground this is straightforward, but on a slope the ground falls away beneath the platform, so a deck that is under 30cm at one end can be well over it at the other. To stay clearly within permitted development, measure at the lowest point of the ground under the deck — if any part of the platform sits more than 30cm above the ground there, the right is likely lost.

The 50% coverage calculation totals the footprint of the new decking and adds it to every other extension, outbuilding, shed and similar structure already in the garden, then compares that against the land around the original house. Conservatories, side extensions, large sheds and summerhouses all count. Because the comparison is against the original house, properties that have already been extended have less remaining allowance, and a modest new deck can be enough to cross the line.

A simple worked example shows how the coverage test bites. Suppose the land around your original house measures 100 square metres. The 50% limit means the combined footprint of all structures must stay under 50 square metres. If you already have a 20 square metre extension and a 10 square metre shed, that is 30 square metres used, leaving 20 square metres of allowance. A 25 square metre deck would tip the total to 55 square metres — over the limit — and would need a planning application, even though the deck on its own is well under half the garden. Running the numbers before you build is the only reliable way to know which side of the line you are on.

Permitted development is not the only consideration

Staying within permitted development means you do not need a planning application, but it does not override everything else. A few points are worth keeping in mind:

• Building Regulations are separate from planning. Most ordinary low garden decking does not need Building Regulations approval, but raised or structurally significant decking can raise structural and safety questions worth checking with building control.
• Boundaries and overlooking: raised decking that lets you see directly into a neighbour's garden can attract objections and is one reason raised decks more often need permission.
• Covenants and leases: separate from planning law, your deeds, a restrictive covenant or a lease may limit what you can build regardless of permitted development.

The rules can also vary between England, Scotland, Wales and Northern Ireland, and they change over time. The definitive answer for your property always comes from your local planning authority, and a free pre-application check or a Lawful Development Certificate can give you certainty before you start.

Proving a deck is permitted development

Permitted development is a legal right, not a piece of paper, so a deck that genuinely meets the tests needs no approval at all. The difficulty comes later: if you sell the house, a buyer's solicitor may ask for evidence that garden works were lawful, and 'we were sure it was permitted development' is harder to rely on than a formal document. For raised, large or boundary-hugging decks in particular, it is worth creating a clear record.

Two routes give that certainty:

• A Lawful Development Certificate (LDC): you apply to the council, which formally confirms the deck was lawful — a useful safeguard for the future even though it is not planning permission.
• A written check with the planning department: a record of the council confirming your deck falls within permitted development, kept with your house paperwork.

Keeping your own dated photos, measurements and a sketch of the deck's height and footprint also helps demonstrate it met the 30cm and 50% tests at the time. None of this is mandatory for a clearly compliant low deck, but the more borderline the deck — close to 30cm, close to the coverage limit, or near a boundary — the more valuable a documented confirmation becomes.

Frequently asked questions

Sources & further reading

• Planning Portal (gov.uk) — decking permitted development
• Planning Portal (gov.uk) — permitted development rights
• Checkatrade — decking planning and cost guide

Figures on this page are typical UK ranges drawn from published sources and depend on your specific garden. They are guidance, not a quotation.