Garden decking does not need planning permission in England if it is no more than 300mm (approximately 12 inches) above the existing ground level. Decking exceeding 300mm is classified as a raised platform and requires a planning application. The decking area also counts towards the 50% maximum garden coverage under PD rules. This guide covers the critical 300mm threshold, raised platform rules, and conservation area restrictions.
The Basic Rule
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Key Decking Planning Facts (England, 2024)
- 300mm (12 inches) is the critical height threshold above ground level
- Above 300mm: classified as raised platform, requires planning permission
- Decking counts towards the 50% garden coverage PD limit
- No minimum boundary distance for ground-level decking
- Building regulations: rarely needed for standard domestic decking
- Raised decking with handrails may need building regulations for barriers
Under the GPDO, decking that is no more than 300mm (30cm) above ground level is generally permitted development. It's treated as a minor alteration to the garden rather than as development requiring permission.
Decking over 300mm high is classified as a raised platform, and raised platforms are specifically excluded from permitted development under Part 1, Class A. 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 measurement is from the natural ground level directly below each point of the decking to the top of the decking surface.
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.
Listed Buildings and Conservation Areas
As with most permitted development, listed buildings need separate consent. Even low-level decking in the garden of a listed building requires listed building consent.
In conservation areas, permitted development rights for raised platforms (including decking over 300mm) are already excluded. Low-level decking under 300mm is usually fine, but check for Article 4 directions.
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 more of a grey area. Technically it's a hard surface rather than a raised platform — similar to the rules for driveways. But if it creates any elevation above the natural ground level, it's safest to check with your council.
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.
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)
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
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.
Costs
- Basic softwood decking: £50-£100 per m²
- Composite decking: £80-£150 per m²
- Hardwood decking: £100-£200 per m²
- Planning application (if needed): £258, 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.
Frequently Asked Questions
How high can decking be without planning permission?
300mm (30cm) above the natural ground level. Any higher and it's classed as a raised platform, which is not permitted development.
Do I need planning permission for decking in my back garden?
Not if it's under 300mm high, doesn't cover more than 50% of the garden (combined with other structures), and your property isn't listed or subject to special restrictions.
Can I build decking right up to my boundary?
Yes, for low-level decking. There's no minimum distance from boundaries for decking under 300mm. However, if the decking is raised and needs permission, the council will consider the impact on neighbours.
Does decking count as an extension?
Not in planning terms if it's under 300mm. It doesn't count towards the depth limits for rear extensions. However, it does count towards the 50% garden coverage calculation.
Do I need planning permission for a hot tub on decking?
The hot tub itself doesn't usually need planning permission if it's in the rear garden. But if the decking it sits on is over 300mm, you'd need permission for the decking. Check that the deck is structurally rated for the weight of a filled hot tub (typically 1,500-2,000kg).
Can my neighbour complain about my decking?
If the decking is permitted development, there's no planning consultation. However, if raised decking causes overlooking or privacy issues, neighbours can complain to the council. If the decking actually needs permission you don't have, the council may take enforcement action.
Does composite decking need planning permission?
The material doesn't matter — the same rules apply to timber, composite, or any other decking material. It's the height and position that determine whether permission is needed.
Check Your Area
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Further Reading
Related Guides
- How to Appeal a Planning Decision
- Permitted Development Rights Explained
- Planning Enforcement: When Rules Are Broken
- What Are Material Planning Considerations?
- Conservation Areas and Planning
- How Much Does Planning Permission Cost?
- How Long Does Planning Permission Take?
- Retrospective Planning Permission
- Do I Need Planning Permission for a Shed?
- Do I Need Planning Permission for a Garage?
- Do I Need Planning Permission for a Driveway?
Check Planning in Your Area
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- Birmingham City Council Planning Applications
- Bristol Planning Applications
- Cardiff Planning Applications
- Sheffield Planning Applications
Browse Planning by Region
Planning rules — especially permitted development rights — vary significantly depending on where you live. Article 4 directions in London and conservation areas across the South East can remove PD rights entirely.
- Planning in London — 32 boroughs, extensive Article 4 directions removing PD rights
- Planning in the South East — High concentration of conservation areas and Green Belt restrictions
- Planning in the North West — Manchester growth corridor, post-industrial regeneration areas
- Planning in Yorkshire — Mix of urban renewal and rural AONB protections
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Search Your Postcode FreeDisclaimer: PlanWatch provides general information about UK planning processes. This content is not legal advice. Planning law is complex and varies by local authority. Consult a qualified planning consultant or solicitor for advice specific to your situation.