PVC Roof Repairs and Roof Restorations
PVC (Polyvinyl Chloride) is a synthetic plastic polymer used in the manufacturing of several products including roof membranes.PVC is the third most widely manufactured synthetic plastic. In the manufacturing of PVC roof membranes,
plasticizers are added to the PVC to increase the flexibility of the plastic and increase elasticity. Plasticizers are additives meant to lower the cold-flex temperatures and increase the durability to PVC.Over time,these plasticizers evaporate
or migrate out of the plastic.This process is accelerated when the PVC material is exposed to UV,heat and thermal cycles.As the plasticizers dry out of the PVC roof membrane, the roof loses its ability to move with the building and thermal
cycling.The PVC roofing then becomes brittle,cracks and separates beginning at the seams and areas of heavy wear on the roof such as ponds,waterways and drains.
PVC roof membranes are single-ply roofing membranes that come in rolls and therefore have seams like rolled cap sheet.These roof membranes are generally anchored to the roof deck,creating holes in the roof deck where the single-ply
material is bolted to the roof deck. As the roof thermal cycles,expands and contracts,the fasteners come loose.As the solar reflectance declines,up to 20% every three years,the PVC becomes brittle and loses the ability to move.Seam separation
and stress or fracture cracks can appear.It is not surprising that one pond on an aged PVC roof can feed dozens of leaks that are extremely difficult to pinpoint.
PVC, like other single-ply materials,requires special flashings at the penetrations and around equipment curbs.Seams are either heat welded or “glued down”.Some PVC used in cold climates has been known to stress-shatter causing hundreds
of little star-like fractures in each sheet,leaving even more opportunity for water intrusion.When PVC reaches the end of its life cycle,it has to be torn off and replaced like traditional roof materials.
