How to Install a PVC in Accordance With Section 07540
The Construction Specifications Institute, or CSI, publishes specifications for a wide variety of construction materials and supplies. Section 07540 of the CSI Spec-Data manual sets forth technical data and installation standards for exterior roofing membranes made of thermoplastics such as polyvinyl chloride -- known as PVC. Thermoplastic roofing membranes are installed on flat or low-slope roofs, to prevent leaks and shed water off the roof surface. Increasingly, PVC membranes are replacing traditional flat roofing materials such as asphalt covered with gravel, because they are more UV-resistant and the seams between sheets are heat-sealed -- forming a continuous protective layer over the roof. PVC membrane sheets are glued directly to the insulated panels that form the substrate of the roof. Does this Spark an idea?
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Things You'll Need
- Glue roller with solvent-resistant nap
- Paint roller
- Broom
- Hot air PVC seam welder
- Hammer
Instructions
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1
Inspect the surface of the insulated roof substrate to verify that it is clean, smooth and free of contaminants. Ensure that the mechanical fasteners securing the substrate are flush with the surface.
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2
Unroll the PVC membrane, and allow it to relax at least 15 minutes in temperatures above 60 degrees Fahrenheit or at least 30 minutes in temperatures below 60 degrees.
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3
Arrange several contiguous sheets on the roof surface, overlapping each by 3 inches to provide room for hot welding each seam.
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4
Fold one-half of the first sheet back, to expose the roof substrate and the reverse side of the sheet. Use a solvent-resistant nap roller to apply the manufacturer's recommended adhesive to the substrate and the back of the PVC sheet. Do not apply adhesive to the overlapped edge of the sheet that will be heat-welded to the next sheet. Adhesive should be applied at a rate of 60 square feet per gallon for each surface -- without forming puddles or globs.
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Allow the adhesive on the membrane to dry to a tacky consistency.
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Press the PVC sheet back onto the substrate, and roll it with a dry roller or stroke it with a broom. This removes wrinkles and air pockets, and ensures adhesion. Repeat the procedure for the remaining half of the sheet, and continue until all sheets in the row are adhered to the substrate.
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Follow the manufacturer's directions with a commercially available hot air welder, to seal the overlapping seams between each sheet. Before beginning, test the welds on 2-foot strips of membrane, to verify that the seams have adequate strength and the heat welder is operating at the correct temperature. Repeat this test any time work is discontinued or the hot air welder is allowed to cool down. After all seams between the sheets have been welded, allow 8 hours for cooling and test the seams for continuity and integrity.
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8
Secure the adhered PVC sheets along roof edges, walls, curbs and anywhere a change in the roof slope exceeds 1 1/2 inches in 12 inches. Use factory-coated steel fasteners with metal or plastic fastening plates that comply with FM Global standard FMG 4470 for securing membranes to substrate.
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