The Right Joining Methods and Abutment Details
Typically in a pitched roof scenario, a roof window will directly lie in the path of deluging water being delivered to the head of the window from above. This places stress on two aspects; 1. the integrity of the frame joints and 2. the integrity of the abutment details.
Rooflights for flat roofs are designed to be installed on upstands – typically made of timber. These upstands lift the rooflight away from the roof surface by approximately 150mm. Other than the rainwater that directly falls on them, water never accumulates on the rooflight frame; this means that there is less emphasis on the ability of the rooflight frame joints to withstand a deluge of water.
Roof windows designed specifically for installation into pitched roofs therefore require carefully considered jointing methods. In addition, the abutment details, perimeter frame details and flashing kits must be specifically designed to withstand ingress of water when installed on a pitched roof.