Will Tar Mess Up PVC Roofing?

Thermoplastic

• Polyvinyl chloride is a composite material known as thermoplastic. It is formed by heating plastic material, layering the material with fibrous material and allowing it to cool. Once cooled, the material is solid and durable but maintains some flexibility, which allows it to withstand stresses such as weight and wind. PVC roofing is sold in sheets measuring 4- to 12-feet in width. The materials thickness varies but is within the range of 45 to 90 mils thick. Roofs are damaged when they are exposed to high heat and sun over long periods of time. Hail, debris, wind and rodents can also damage PVC roofs. Repairs are made using welders and patches.

Heat Welding

• PVC roof plastic returns to a malleable state when exposed to heat. Welding tools are used to perform thermoplastic welding techniques such as pendulum welding, speed welding and mirror welding. These methods are used to excise a damaged portion of material, seal the edges and place and seal a patch over the area. Following these techniques ensures that the roof will not receive additional structural damage from burns or cracks. Hot tar, when placed on a PVC roof, can damage the roof structure. Since high temperatures cause the PVC material to enter a malleable state, hot tar's uncontrolled temperatures combined with its weight, can cause material to weaken, bend, burn and crack. Controlled, direct heat such as that provided by welders is the preferred PVC roof repair method.

Tar and Roof Asphalt

• Roofing varieties and styles range from flat roofs to gabled to domes. The materials used for these projects also vary. Tile, slate, metal, asphalt or tar shingles as well as wood shakes and PVC panels, are all used as roofing materials. Despite these differences in style and material, roofs have similar functions and design. Roof coverings are placed on top of under-roofing materials that provide a weatherproof membrane between the outer roof and the home's interior. Tile roofs use a mortar to create a seal. Other roof types use plywood sheathing and a combination of roofing cement, nails and other fasteners. Tar and roof asphalt are used to repair and seal damaged asphalt and tar roofs. These repair materials are not suited for tile, slate, metal or PVC roofs.

Considerations

• PVC roofing can be used for residential construction but it is best suited for use in buildings that require no insulation. PVC roofs are utilitarian and well-suited for low-maintenance and temporary structures where they can be easily installed, maintained and replaced as needed.