Transom (architecture)

For other uses, see Transom (disambiguation).
Door of 10 Downing Street, London, showing a transom separating the door from the window above

In architecture, a transom is a transverse horizontal structural beam or bar, or a crosspiece separating a door from a window above it. This contrasts with a mullion, a vertical structural member.[1] Transom or transom window is also the customary U.S. word used for a transom light, the window over this crosspiece.[1][2] In Britain, the transom light is usually referred to as a fanlight, often with a semi-circular shape, especially when the window is segmented like the slats of a folding hand fan. A prominent example of this is at the main entrance of 10 Downing Street, the official residence of the British prime minister.

  1. ^ a b "The Efficient Windows Collaborative: Glossary". Archived from the original on 2007-11-28. Retrieved 2007-12-13.
  2. ^ "What is a transom window?". Big Blue Window. Archived from the original on 2007-12-28. Retrieved 2007-12-13.