PVC roofs have experienced similar criticism to that of TPO roofs when they were first introduced. While not as popular as many other commercial flat roof systems being installed here in Texas, PVC is one of the pioneering single-ply roof materials in the industry. PVC stands for Polyvinyl Chloride and was first produced by a company called Trocal first installed in Germany back in the mid 1960’s. Within a few short years, Trocal PVC covered millions of square feet all over the world and actually set the stage for market dominance for several decades.

The primary difference between PVC roofs and PVC pipes is the hardness factor. The reason PVC roofs are not hard plastic like PVC pipe, is the presence of plasticizers. Without getting into it too much, plasticizers are chemical components that allow the PVC to be flexible; PVC in its “natural” state is rigid, like PVC pipe. Early on, there were problems with the plasticizers, and PVC roofs would inherently shrink and become brittle after a few years in areas where the temperature shifts from hot to cold were common.

Plasticizers can migrate to adjacent materials. Therefore, it is important that PVC roofing be installed over substrates that are compatible with the PVC material. Migration can also occur if the PVC is installed directly over asphalt, or polystyrene insulation with no separator between them. This is often referred to as “divorcing” or “separating” boards or sheets. The “board” is typically a piece of rigid roof insulation board, not wood, although it can be made from wood particles.

PVC roofing comes in a variety of thicknesses, but the most common are 50 mil and 60 mil. Other thicknesses are 40 mil, and then there are fleece-back materials (PVC membrane with a fuzzy underside) that go up to 115 mils.

pcv_detail

PVC roofs are installed in three different ways:

  1. Mechanically fastened – the PVC roof is held in place by being attached to the substrate/deck using screws or other types of fasteners, depending on the deck type.
  2. Fully Adhered – the PVC roof is attached to the substrate using special adhesive (glue). There are different adhesive options.
  3. Ballasted – the PVC roof is laid across the roof loosely, secured only at the roof perimeter and around roof penetrations such as pipes, air conditioning units, etc., and held in place with ballast, which usually consists of smooth river rock although other options are available.

Typically a PVC system is a more expensive product than the TPO and given that they both offer comparable warranties (20 year) and PVC tends to be more chemical resistant. PVC is a solid option for restaurants, airports and commercial facilities with grease, oil and chemical concerns, and environments that experience diluted acidic effluents. Its white reflective surface provides a cooling effect that owners desire to provide energy savings in warmer climates. It has been tested in the industry now for more than 35 years and now meets the most stringent codes in a wide variety of climates.

LSR works with some of the best PVC manufacturers in the industry and we will install according to the customers specification of this system.