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 Roof Windows (Velux) in Welwyn Hatfield?
Installing roof windows (also known as Velux windows or skylights) into an existing roof slope. Roof windows are a popular way to bring light into loft spaces without the cost of a full dormer.
Planning in Welwyn Hatfield
88%
of planning applications granted
95%
decided within the statutory or agreed time
54%
of householder applications decided within 8 weeks
In the year to December 2025, Welwyn Hatfield decided 630 planning applications. 424 of these were householder projects such as extensions, loft conversions and outbuildings, of which 87% 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 Welwyn Hatfield
Welwyn Hatfield has 9 conservation areas. These include Ayot Green, Ayot St Lawrence, Beehive, Essendon, Northaw Village, Old Hatfield. 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 Welwyn Hatfield planning department before starting work to confirm whether your property is affected by any special designations.
Permitted Development Rules for Roof Windows (Velux)
Generally permitted under Part 1, Class C of the GPDO. Roof windows are permitted provided they do not protrude more than 150mm beyond the plane of the roof slope. Side-facing windows at upper-floor level must be obscure glazed and non-opening below 1.7m from the floor.
Conditions
- 1Must not protrude more than 150mm beyond the existing roof plane
- 2Side-facing windows (on a wall or roof slope forming a side elevation) must be obscure glazed and non-opening below 1.7m from the floor
- 3The window must not result in the roof exceeding the existing ridge height
Size and Dimension Limits
- Protrusion: maximum 150mm beyond the roof plane
- No specific size limit for individual windows
When Permitted Development Does Not Apply
- In conservation areas, roof windows on the principal or highway-facing elevation may not be PD
- Listed buildings require listed building consent
- Multiple roof windows may cumulatively change the character of the roof, potentially requiring PP
What About Building Regulations?
Building regulations approval is likely required
Building Regulations may apply depending on the structural alteration to the roof. Covers structural integrity of the roof after cutting rafters, thermal performance (Part L), and fire safety (means of escape if the room is a habitable loft). A FENSA-registered installer or building control notification is needed for the glazing.
Building regulations are separate from planning permission. Even if your project is permitted development, you may still need building regulations approval. Contact Welwyn Hatfield building control or use an approved inspector.
How to Apply in Welwyn Hatfield
If you need planning permission for your roof windows (velux), you can apply through Welwyn Hatfield'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 Welwyn Hatfield. 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 standard roof windows within PD limits. Enforcement may occur if windows overlook neighbouring properties without being obscure glazed where required, or in conservation areas without consent.
Frequently Asked Questions
Do I need planning permission for roof windows (velux) in Welwyn Hatfield?
Does roof windows (velux) in Welwyn Hatfield need building regulations?
How do I apply for planning permission in Welwyn Hatfield?
How long does planning permission take in Welwyn Hatfield?
What percentage of planning applications does Welwyn Hatfield approve?
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