Thermoplastics

Giuseppe from Ontario asked:

I have a PVC coated flange, can this be heat welded to a TPO membrane, since both are thermoplastics?

John Kenney from Cotney Consulting Group says:

Unfortunately, PVC and TPO are not compatible with each other and do not weld correctly. Even if it appears to be welded, it is a false weld and fails.

Marty from Go Roof Tune Up says:

Thermoplastic Polyolefins and Polyvinyl Chloride should not be welded to each other. Consult the manufacturer of the existing roof system for future direction.