vents, The following information for fastening rigid foam insulation as a substrate for adhered EPDM roof membranes is typical, but fastening requirements can vary with membrane or insulation manufacturer, roof height, wind zone / exposure designation, or jurisdiction.
No gap between insulation panels should be greater than ¼". Gaps greater than this should be filled with an appropriate material.
For roofs at a height of less than 60', the perimeter is defined as .4 times the roof height above the ground.
4'x4' insulation sheets should have at least 5 fasteners. 4'x8' sheets should have a minimum of 8 fasteners per sheet.
Insulation sheets within the roof perimeter: 4'x4' insulation sheets should have at least 8 fasteners. 4'x8' sheets should have a minimum of 16 fasteners per sheet.
Extra fasteners should be installed around penetrations like skylights, vents, pipes, chimneys, hatches, etc.