A heat sealable tape of a copolymer of tetrafluoroethylene and at least about 15% by weight of a highly fluorinated monomer. The copolymer has a melt viscosity of no greater than about 1000 PaS at 372.degree. C. and an application temperature of no greater than about 250.degree. C. The invention further provides for a seam formed from two sections of sheet material, especially fabric, wherein each sheet has at least one fluoropolymer surface. The sections are sealed one to the other by application of heat sealable composition over one fluoropolymer surface of each section. The heat sealable composition comprises a copolymer of tetrafluoroethylene and at least about 15% by weight of a highly fluorinated monomer, the copolymer having a melt viscosity of no greater than about 1000 PaS at 372.degree. C. and an application temperature of no greater than about 250.degree. C. In preferred embodiments, building structures and manufacturing equipment are fabricated from sheet material having the seam formed from two sections of sheet material wherein each sheet has at least one fluoropolymer surface.