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Skylight windows in a converted attic

The skylight is a window in the roof of a building. It is used to light and ventilate the roof space. In the case of lofts converted for residential purposes, it also offers a view of the surroundings.

Lying and standing skylight

Lying (left) and standing skylight in a hipped roof

Based on the design, skylights can be divided into two groups:

Lying roof window
A window set into the roof surface with the same angle of inclination as the roof. In modern construction, commonly referred to as skylights .
Standing skylight
A window in a dormer .

Today, horizontal roof windows are produced industrially and their width is matched to the usual rafter spacing . As they are relatively easy to install, they are often used when the roof space is subsequently expanded. To open, they can usually be tilted around their central horizontal axis. The windows are also increasingly combined with both a central axis as a fulcrum of the frame at the top end to open, so-called folding pivot window . Skylights adjacent to the eaves can be combined with an underlying facade connection window . Since the windows are exposed to increased heat radiation, especially in summer, they are often provided with an external or internal sun protection blind, or completely provided with so-called " intelligent glass ". The external roller blinds offer better heat protection, but are susceptible to wind.

The dormer required for a vertical skylight is comparatively more complex to construct, but allows standard windows to be installed on the wall and better use of the space behind it.

Special forms


The skylight is a window opening in the ceiling of a room and is more often used on flat or slightly sloping roofs. In contrast to the regular skylight, it does not offer a view of the surroundings, but primarily serves to illuminate the interior.

The skylight window is a small, horizontal skylight that is mainly used in undeveloped attic spaces ( attics ). It is mainly used for lighting, larger roof hatches ( roof hatches ) also allow access for work on the roof (roofer, chimney sweep , antenna fitter , etc.).

A roof outlet can be used as an alternative to the roof balcony. There is a construction method for this in which the upper part of the roof window can be opened up to 45 °, the lower part is pushed out and the side railings fold open. This variant saves space and can be quickly folded out and in. The roof outlet is also suitable as an escape route.

Norms and standards

The following standards are relevant for roof windows :

  • DIN 276 costs in construction / ÖNORM B 1801-1 building project and property management : cost group 362 roof windows, roof openings
  • DIN 5034 -3.6 daylight in interiors - Part 3 calculation and in particular Part 6: Simplified determination of useful dimensions of skylight openings in roof areas

About thermal properties:

  • EN ISO 10077-1 Thermal behavior of windows, doors and shutters - Calculation of the heat transfer coefficient - Part 1: General
  • EN ISO 12567-2 Thermal behavior of windows and doors - Determination of the heat transfer coefficient using the heating box method - Part 2: Skylights and other cantilevered windows

Various standards of structural fire protection are also relevant :

  • EN 14351-1 Windows and doors - Product standard , performance characteristics - Part 1: Windows and external doors without properties regarding fire protection and / or smoke tightness
  • DIN 18232 smoke and heat exemption for smoke and heat extraction in the attic

To the accessories:

  • EN 12833 Roller shutters for roof windows and winter gardens - Resistance to snow load - Test method
  • EN 1627 Burglar- resistant building products


  • Central Association of the German Roofing Trade e. V., Professional Association for Roof, Wall and Sealing Technology e. V. (Ed.): Roof, wall and sealing technology. Technical book for training and further education in the roofing trade . 8th edition. Verlagsges. Müller, Cologne 2008, ISBN 978-3-481-02492-5 (for Germany).
  • E. Sälzer, J. Maack: Soundproofing of pitched roofs and roof windows. Final report . Fraunhofer IRB Verlag, 2009, ISBN 978-3-8167-7922-3 .

Web links

Commons : Skylights  - collection of pictures, videos and audio files
Wiktionary: roof window  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Hans Koepf , Günther Binding : Picture Dictionary of Architecture (= Kröner's pocket edition . Volume 194). 4th, revised edition. Kröner, Stuttgart 2005, ISBN 3-520-19404-X , p. 115.