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July 06, 2018

Understanding PVC Roofing Installation

When considering a new roofing installation, it is expected of homeowners to look at the cost of metal panels, ceramic tiles, or shingles. These are undoubtedly top-quality materials. However, roofing professionals also prefer specialised products such as polyvinyl chloride (PVC) roofing membranes.

Predominantly, PVC roofing membranes are used in commercial and industrial buildings. That said, there are some PVC coverings manufactured specifically for residential functionality and beauty.

PVC coverings are specialized for flat or low-slope roofs. These roof structures cannot be covered by standard shingles because water tends to back up across the surface. The overlapping design of shingles provides an easy way for moisture to leak into your home. PVC membranes, on the other hand, comprise one continuous covering thus making leaks rare.

Depending on the type of property, regional, and local weather patterns, PVC membrane systems can be customized to include several film layers. Each layer has a specific thickness ranging from 50 to 80 mil. If you do not have high-traffic on your roof, 50 mil is sufficient.

Installing PVC Roofing

The longevity and proper service of your roofing system will be determined by the quality of installation among other factors. Inasmuch as PVC roofing membranes are excellent coverings for your roof, initial incorrect installation, rather than inherent roof flaws is the major cause of premature failure of PVC roofing.

Insulation

Before installing the PVC roof membrane, roofing professionals put in some insulation board. The common types of boards are EPS or ISO foam boards. The R-Value of these boards ranges between 4-R and 6-R for every inch of insulation thickness. The insulation helps in heat loss reduction thus saving energy.

There are different ways of installing a PVC roofing membrane. Below are some of the common ones:

Fully-Adhered Assembly

In this installation technique, the PVC membrane is attached to the substrate with the help of a special adhesive. It is a quicker and much simpler installation method. It is recommended in cases where the PVC membrane cannot be attached using fasteners or screws. This is especially on substrates such as the structural concrete deck.

For a fully-adhered membrane to last longer, it must be stronger along the perimeter. This enhances wind uplift. Compared to mechanically attached systems, fully-adhered membranes don’t have the flutter.

One of the main disadvantages of this type of installation is that the adhesive holding the membrane in position becomes loose when condensation forms underneath the PVC membrane.

Mechanically Attached Assembly

Instead of using adhesive, the PVC roof is attached to the substrate using barbed plates and heavy-duty screws. This installation is much firmer compared to the fully-adhered PVC installation and can stand even hurricane-level winds.

Mechanically-attached installation is best suited if your building is in an area frequented by high winds. This could be on a high hill or along the coastline.

Ballasted Install

This is where the PVC roofing membrane is loosely laid across the substrate instead of being glued or fastened in place. Ballast is used to hold the membrane in position. The ballast is a mixture of manufactured concrete pavers, washed river rock, and other substantially heavy materials.

Irrespective of the installation procedure you choose, ensure the PVC roofing system is properly sealed with a hot air welder. This is important as it gives the roof a superior seam strength and ensures the membrane is resistant to wind blow offs and leaks. The welder temperature should be adjusted upwards during winter so that you can get a strong bond at the seams.