Do I Need Planning Permission for Decking?

01

The Basic Rule

Under the GPDO, decking that is no more than 300mm (30cm) above ground level is generally permitted development. The government's technical guidance treats garden decking as a "building" under Part 1, Class E, which allows it provided it is not more than 0.3 metres high.

Decking over 300mm high is classified as a raised platform ("a platform with a height greater than 0.3 metres", Part 1, para I), and raised platforms are specifically excluded from permitted development under Class E (para E.1(h)) and, for decking attached to the house, Class A (para A.1(k)(i)). You'll need planning permission.

What Does 300mm Mean in Practice?

300mm is roughly one foot. On flat ground, most standard decking (frame plus boards) comes in at about 150-200mm — well within the limit. Problems arise when:

• The garden slopes away from the house, meaning the far edge of the decking is higher above ground level
• The decking is built on a raised frame to create a level surface on uneven ground
• Steps or multiple levels push parts of the decking above 300mm
• The decking is built over a basement lightwell or similar void

The Order itself does not say how to measure the 0.3 metres on a slope. The government's technical guidance says heights are measured from ground level, which on sloping ground is "the highest part of the surface of the ground next to the building", and that decking laid on top of the ground is not part of ground level. That is guidance, not law, so on a sloping garden check with your council or get a lawful development certificate before you build.

02

Coverage Limits

Even low-level decking counts towards the general permitted development rules:

• Together with all other extensions and outbuildings, it must not cover more than 50% of the garden
• It must not be forward of the principal elevation (front of the house)

This 50% rule is cumulative — sheds, garages, and other outbuildings all count towards the same limit. If you're planning multiple garden improvements, check the combined footprint carefully.

03

Listed Buildings and Conservation Areas

Class E permitted development does not apply within the curtilage of listed buildings (para E.1(g)), so even low-level decking in the garden of a listed building needs planning permission. Listed building consent is needed as well only if the decking is fixed to the listed building or otherwise affects its character (Listed Buildings Act 1990 s7).

Raised platforms (decking over 300mm) are outside permitted development rights everywhere, not just in conservation areas. In a conservation area, National Park, National Landscape, the Broads or a World Heritage Site, Class E also allows nothing between a side wall of the house and the boundary (para E.3). Low-level decking elsewhere in the garden is usually fine, but check for Article 4 directions.

04

Decking at the Front of the House

Decking forward of the principal elevation is not permitted development. If you want a raised deck at the front of your house, you'll need planning permission.

Low-level decking (under 300mm) at the front is not covered either. The technical guidance treats decking as a Class E building, and Class E allows nothing forward of the principal elevation (para E.1(c)). Paving is different: front-garden hard surfaces have their own rules, covered in our driveways guide. Check with your council before building decking at the front.

05

Balustrades and Railings

If your decking needs balustrades or railings (generally required for safety if the deck is more than 600mm above ground), the height of the railings doesn't count towards the 300mm measurement — the 300mm limit applies to the deck surface itself.

However, if the decking is over 300mm and needs permission, the railings will be part of the planning assessment, particularly regarding overlooking and privacy for neighbours.

06

Privacy and Overlooking

This is the biggest planning concern with raised decking. A deck that's 500mm or more above ground level can give you a direct view into your neighbour's garden or home that didn't exist before. Councils consider:

• Loss of privacy to neighbouring properties
• Overlooking into gardens and windows
• Noise from the elevated area (people tend to spend more time on decks than at ground level)

If you need planning permission for raised decking, the council may impose conditions like:

• Privacy screens
• Obscure planting
• Restrictions on hours of use (rare but possible)

07

Building Regulations

Decking doesn't usually require building regulations approval. However:

• Structural adequacy is your responsibility — the deck must be safe
• If the decking is over 600mm high, balustrades must meet building regulations (at least 1.1m high for domestic decking)
• Electrical installations (lighting, sockets) must comply with Part P

08

The Party Wall Act

Decking built within 3 metres of a neighbouring building may trigger Party Wall Act obligations if excavation is involved. Simple surface-level decking on flat ground is unlikely to trigger the Act, but decking on significant foundations might.

09

Costs

• Basic softwood decking: £50-£100 per m²
• Composite decking: £80-£150 per m²
• Hardwood decking: £100-£200 per m²
• Planning application (if needed): £272 (from 1 April 2026; fees rise each April: MHCLG fee schedule), with decisions typically within 8 weeks

A typical 15m² rear deck costs £1,500-£3,000 for a professional installation.

If decking has already been built above 300mm without planning permission, retrospective planning permission is possible — the council will assess it on its planning merits. Check your local council's planning portal, e.g. Cardiff or Sheffield, for specific requirements in your area.