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 Bi-Fold or Sliding Doors in Somerset?
Installing bi-fold, sliding, or French doors, typically to open up a living space onto a garden or patio. Replacing an existing window or door opening with bi-folds is usually PD; creating a new large opening in the wall has additional considerations.
Important: Additional Restrictions May Apply in Somerset
Somerset has conservation areas. 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.
Somerset has Article 4 directions in force. Article 4 directions remove specific permitted development rights in defined areas. If your property is covered by an Article 4 direction, you may need planning permission for work that would normally be permitted. Contact Somerset planning department to check whether an Article 4 direction applies to your property.
Check with Somerset planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for a Bi-Fold or Sliding Doors
Generally permitted. Replacing existing doors or windows with bi-fold or sliding doors is treated as improvement and does not usually require planning permission. Enlarging the opening may be PD under Part 1 provided it does not significantly alter the building's appearance.
Conditions
- 1Replacing an existing door or window with bi-folds of a similar size is generally PD
- 2Enlarging the opening requires structural work and Building Regulations approval
- 3Materials and appearance should be in keeping with the existing property
- 4Rear installations are more likely to be PD than front-facing ones
Size and Dimension Limits
- No specific PD dimension limits for replacement doors
- Structural limits depend on the wall type and lintel requirements
When Permitted Development Does Not Apply
- Listed buildings require listed building consent
- In conservation areas, bi-folds on front or highway-facing elevations may need PP
- Large openings in structural walls require engineer-designed lintels or steel beams
- Ensure adequate drainage and threshold detailing to prevent water ingress
What About Building Regulations?
Building regulations approval is likely required
Building Regulations approval is required covering structural support (steel beams or lintels for large openings), thermal performance of the glazing (Part L), safety glazing (Part K), security (Part Q, PAS 24), and ventilation. FENSA or CERTASS-registered installers can self-certify the glazing element.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact Somerset building control or use an approved inspector.
How to Apply in Somerset
If you need planning permission for your bi-fold or sliding doors, you can apply through Somerset'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 Somerset. 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 rear-facing bi-folds replacing existing openings. Higher risk in conservation areas or on front elevations. The main practical issue is ensuring Building Regulations compliance for the structural opening.
Find a Window Fitter in Somerset
Browse local window fitters on Tradesfolk. Read reviews, compare quotes, and hire with confidence. 100% free for homeowners, always.