This is general guidance based on standard permitted development rights in England. Rules differ for listed buildings, conservation areas, and properties with Article 4 directions. Always confirm with your local planning authority before starting work.
Do I Need Planning Permission for a Decking in St Helens?
Installing timber or composite decking in your garden. Decking is generally permitted but must not be raised more than 300mm above ground level, as higher decking is treated as a raised platform with stricter rules.
Planning in St Helens
94%
of planning applications granted
99%
decided within the statutory or agreed time
81%
of householder applications decided within 8 weeks
In the year to December 2025, St Helens decided 495 planning applications. 270 of these were householder projects such as extensions, loft conversions and outbuildings, of which 96% were granted.
Planning statistics: MHCLG planning application statistics, the year to December 2025. Conservation area and Article 4 data: planning.data.gov.uk, © Historic England / Crown copyright. Open Government Licence v3.0.
Important: Additional Restrictions May Apply in St Helens
St Helens has 14 conservation areas. These include Earlestown, George Street Quarter, High Street, Newton-le-Willows, Rainford, Rainhill. If your property is in a conservation area, some or all permitted development rights may be restricted. For example, you may need planning permission for changes that would normally be permitted, including alterations to the roof, cladding, or extensions visible from a public highway.
Check with St Helens planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for a Decking
Generally permitted under Part 1, Class E of the GPDO (treated as an improvement within the curtilage). Decking that does not exceed 300mm above the existing ground level is permitted development. Decking above 300mm is treated as a raised platform and may need planning permission.
Conditions
- 1Must not exceed 300mm above the existing ground level
- 2Counts towards the 50% curtilage coverage limit (combined with outbuildings and extensions)
- 3Must not be forward of the principal elevation fronting a highway
- 4Balustrades and railings on top of the decking count towards the height measurement
Size and Dimension Limits
- Height above ground: 300mm maximum (including any framework)
- No specific area limit, but counts towards 50% curtilage coverage
When Permitted Development Does Not Apply
- Decking over 300mm above ground is a raised platform and may require planning permission
- In designated areas, decking to the side of the house may not be PD
- Overlooking from raised decking is a common neighbour concern
- Drainage and water runoff should be considered
What About Building Regulations?
Building regulations approval is not usually required
Building Regulations do not normally apply to standard garden decking. Structural adequacy is the homeowner's responsibility. If the decking is attached to the house and forms part of an extension or raised platform, Building Regulations may apply.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact St Helens building control or use an approved inspector.
How to Apply in St Helens
If you need planning permission for your decking, you can apply through St Helens's planning department or via the national Planning Portal.
If your project is permitted development and you want written confirmation, you can apply for a Lawful Development Certificate (LDC) from St Helens. This provides proof that your project does not need planning permission, which can be helpful when selling your property.
What Happens If I Build Without Permission?
Low risk for decking at or near ground level. Raised decking over 300mm is a common cause of enforcement action, particularly where it allows overlooking of neighbouring gardens. The council can require removal or reduction of non-compliant decking.
Frequently Asked Questions
Do I need planning permission for a decking in St Helens?
Does a decking in St Helens need building regulations?
How do I apply for planning permission in St Helens?
How long does planning permission take in St Helens?
What percentage of planning applications does St Helens approve?
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