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Last edited 23 Dec 2019
Windows are openings fitted with glass to admit light and allow people to see out. They are often openable to allow ventilation. Rooflights (sometimes described as ‘roof lights’ or ‘skylights’) are windows built into the roof of a building.
|A dome light, lantern light, skylight, ridge light, glazed barrel vault or other element to admit daylight through a roof.|
Rooflights are effective at allowing natural light deep into the centre of a building, particularly where it is not possible to install windows in perimeter walls or where privacy is needed. Where they are openable, they can also be effective at promoting natural ventilation, as they tend to be at the top of buildings and so can benefit from the stack effect. They may also be used to allow access to roofs or to roof terraces.
Some rooflights however can be seen as a poor design solution, contributing little to the architectural form of a building, and simply creating a hole in a roof because without them there would be insufficient natural light. They can also suffer from ponding, dirt accumulation and staining.
BS EN 14351-1 (Windows and doors. Product standard, performance characteristics. Windows and external pedestrian doorsets) suggests that the term ‘roof window’ refers to a window that is in the same plane as the surrounding roof, and has a minimum pitch of 15 degrees. This is as opposed to 'rooflights' which by this definition are installed on an upstand, and so are not in the same plane as the surrounding roof.
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