ensure protrusions are adequately flashed

Protrusions such as pipes and ducts should be adequately flashed where they pass through the sheeting surface. Where ribs have to be cut away to permit penetration, additional framing should be installed as required to support the sheeting.

Depending on the position of the penetration through the roof, special attention should be given to back flashing the sheeting to the ridge or point of water entry up the roof from the protrusion.

In all cases, all cutting and flashings should be so arranged that adequate provision is made for the drainage of all troughs and corrugations.