A roof light is any glazed opening installed in a roof surface to allow natural daylight into the space below, and it can take the form of a fixed skylight, an operable roof window, or a domed light unit on a flat roof.
Types of roof lights
There are several common types, each suited to different roof forms and purposes:
- Roof window — a window set into the plane of a pitched roof, typically hinged at the top or centre so it can be opened for ventilation. Brands like Velux and Fakro are well-known manufacturers. Roof windows sit flush with the roof surface and are installed between the rafters.
- Skylight — a fixed or opening glazed panel, often larger than a standard roof window, designed to flood interior spaces with light. Skylights can be flat, domed, or pyramidal.
- Light dome (rooflight dome) — a circular or rectangular dome made of polycarbonate or acrylic, mounted on an upstand on a flat roof. Light domes are common on commercial and industrial buildings.
- Tubular daylight device (sun tunnel) — a small dome on the roof connected to a reflective tube that channels sunlight down into rooms that cannot accommodate a full-sized roof light.
Installation considerations
Proper installation is critical to prevent leaks. Each roof light comes with a flashing kit designed for the specific roof covering — tiles, slates, or flat-roof membranes. The opening must be framed correctly, with trimmer rafters or additional noggins to maintain structural integrity. Insulation should be continued around the frame to avoid cold bridges.
Building regulations in most regions require roof lights to meet minimum thermal performance standards (U-values) and, if the building is near a boundary, fire-resistance ratings.
Application
Roof lights are used in loft conversions, extensions, kitchens, hallways, and any room where wall windows are insufficient or impossible. They admit up to three times more light than vertical windows of the same size, making them an efficient way to brighten interior spaces while reducing the need for artificial lighting.
Related terms
- Dormer
- Roof pitch
- Flashing
- Loft conversion
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