COP v3.0:installation; overhang

14.10 Overhang 

The length of the overhang of sheeting into a gutter or spouting depends on the pitch of the roof and the site exposure to wind and rain.

The recommended overhang for roof cladding with a pitch between 10° and 35° is 50 mm, and 40 mm is regarded as suitable for a roof above 35°. When the ends of the ribs are not baffled by a spouting and the pitch is below 10°, the overhang should be increased to 70 mm to avoid blow-back.

Underlay must not overhang the gutter line by more than 20 mm, or if eaves flashings are used, terminate on the upper side of the flashing. Do not drape underlay into the gutter.