DA 60-820
26
Technical User Guide
Use a crowbar to loosen the steel plate of the sandwich
roofing sheet, so the flat roofing sheet can be slid 70 mm
underneath the steel plate of the sandwich roofing sheet.
The flat roofing sheet now fits the size measured out.
Mark up the roof duct in the flat roofing sheet at the four
holes.
Draw a straight line between the markers.
Drill a vertical hole in the center where the lines meet.