Electromagnetic Induction Welding: A thermoplastic roof membrane is bonded to fastening plates without membrane penetration or a fastener line at membrane sheet seams. The fastening plates are factory coated with the same material as the roofing membrane and an induction welder tool is used to bond the roof membrane to the plates from above the membrane.
Loose-Laid Air-pressure Equalization System: The membrane is fully adhered around the roof perimeter, but elsewhere the membrane is only loose-laid. This system should only be used over an air-impermeable roof deck or over an air barrier. To compensate for minor air leakage between the membrane and the deck/air barrier, air-pressure equalization valves are installed at prescribed intervals. The valves are one-way: they allow air underneath the membrane to vent out, but outside air is prevented from flowing through the valve and underneath the membrane. As with mechanically attached systems, it is prudent to only specify reinforced membranes for this attachment method. This type of system is susceptible to wind blow off if the vents fail to operate or future roof penetrations are cut through the deck/air barrier and left unsealed. These systems are typically not recommended due to shifting of the insulation board that commonly occurs and the difficulty in detecting leak locations due to the free flow of water underneath