Induction welding technology used for roof membrane attachment began in Europe and has been available in the U.S. for about 15 years. Currently, several U.S. roofing manufacturers offer induction welding-installed systems for TPO and PVC roof membranes. A roof assembly using induction welding is similar to a traditional system where fasteners and plates are used to attach insulation to a structural deck. But unlike a traditional system, a roof membrane is bonded to fastening plates without membrane penetration or a fastener line at the membrane sheet seams.
An induction welding system uses fasteners and coated plates to secure roof board insulation to a structural deck. A TPO or PVC membrane then is attached from above the roof membrane to each plate with an electromagnetic induction welding tool.
At press time, eight manufacturers offer induction welding-installed systems that achieve FM Global's wind-resistance rating when tested as part of a roof assembly. Each manufacturer has an agreement with OMG Roofing Products, Agawam, Mass., to produce fasteners and coated plates for their specific systems, as well as Rhino-Bond® Tool—a stand-up electromagnetic induction welder used on roofs to create a bond between a coated fastener plate and the underside of a roof membrane. For a list of manufacturers currently offering induction welding-installed systems for thermoplastic roofing, see the figure on page 41.