Velux is a brand name that has become a common shorthand for roof lights, the windows set into a sloping roof to bring natural light into a loft or upper floor. Whether a planning application is needed depends on the type of roof light, its position on the roof, and the property's planning status.

Flush Roof Lights: Permitted Development

Under Class C of Part 1 of the General Permitted Development Order, the installation of roof lights or roof windows on a dwellinghouse is permitted development provided they do not project more than 150mm above the roof plane when open, do not reduce the ridge height of the roof, and do not result in the roof light being on a roof slope facing a highway in a conservation area. Within these conditions, flush or near-flush roof lights can be installed on most residential roofs without planning permission.

The 150mm protrusion limit is the key condition. Most standard Velux-type roof lights comply with this when installed flush with the existing roof plane, as they project no more than around 70mm above the roof surface. Centre-pivot windows and top-hung windows within this tolerance are permitted development on most properties.

Conservation Areas

In conservation areas, roof lights on a roof slope that faces and is visible from a highway are not permitted development. A planning application is required for any roof light on a highway-facing roof slope in a conservation area. Roof lights on rear slopes not visible from any highway remain permitted development in conservation areas, subject to the same protrusion limit.

Conservation officers sometimes request that roof lights in conservation areas are of a conservation-style design with a low profile that sits within the roof plane rather than projecting above it. Velux and other manufacturers produce specific conservation roof light models designed to meet this requirement.

Listed Buildings

Listed buildings are excluded from the Class C permitted development right. Any roof light on a listed building, whether on the principal elevation or a rear slope, requires listed building consent and potentially planning permission. The impact on the historic fabric and appearance of the building is carefully assessed, and conservation-style low-profile roof lights are more likely to receive consent than standard projecting units.

Dormer Windows vs Roof Lights

A flat-roofed dormer box that adds significant headroom is not a roof light and is governed by the Class B permitted development rules for loft conversions rather than the Class C rules for roof lights. The distinction matters because the rules are different: a dormer has volume limits and cannot face a highway, whereas a flush roof light is governed only by the 150mm protrusion limit and the conservation area restriction.

Summary

Flush roof lights that protrude no more than 150mm above the roof plane are permitted development on most residential properties and do not require planning permission. In conservation areas, roof lights on highway-facing slopes require planning permission. Listed buildings require listed building consent for any roof light. Dormer windows, which project significantly from the roof, are governed by different rules under the loft conversion permitted development class.