Internal drainage opening or ventilation opening for flat roof of building has cap covering top of pipe leading down from socket in aperture in flat roof covering

摘要

The top layer (4) of the roof covers an insulating layer (3) on top of a watertight layer (2) and a support structure (1). The drainage gulley (5) has a protective cap (8) on top of a short length of vertical pipe held in upper (6) and lower (7) flanged sockets. The pipe fits into further lengths of pipe (10,11). Fireproof material (13,14) is fitted.