This is the situation: We have a flat concrete roof with (from bottom to top) bituminous sheet, insulation, bituminous sheet. There's a blower to be set onto the roof, blower has a stand with a broad flange (only one side drawn):
My question is, how to connect the upper sheet to the blower stand? Due to thermal expansion, there will be movement between the insulating layer and the blower, so simply glueing the sheet to the blower will tear soon.
How to do the connection?