EFW/01 Fakro Flat Roof Kerb 55cm x 78cm (Excluding Window) Structural opening required - 52cm x 90cm. Description: The EFW Flat Roof System makes it possible to install windows on flat or very low-pitched roofs. The system elevates the installation angle of the window by 15, and can be used for installation of opening or non-opening windows. It is normally used to install single windows in the slope of the roof. Windows can also be installed in combinations with a minimum distance of 30 cm between them. This flashing is intended to be used with flat roof coverings such as asphalt with a thickness of up to 8 mm (2x4 mm) and roofing felt. Can be used on roofs with pitches between 0 and 15. Constituents of the system: The EFW system is made up of two basic elements: a wooden housing with insulation material bonded to it, and flashing to join the window to the housing. Brackets for installing the window are included. After installing the wooden housing, it should be properly sealed and fixed to the existing roof covering.