The main reason why PVC roofing is not suitable for a DIY job is due to the heat-welding required for installation. Heat-welding of the seams creates a longer lasting bond than seams held together with tape, but it is a dangerous process and should only be performed by a qualified roofer.
It is also important to note that the main problems that arise with vinyl flat roofing is due to poor installation. Even if a homeowner has a breadth of welding experience, it is best to contact a qualified roofer for the job. Otherwise you run the very likely risk of causing more stress and more costs down the road.
PVC Flat Roof Installation: The Three Methods to Adhere
PVC or vinyl flat roof installation is fairly straightforward. Prepare the roof deck, lay the material, weld the seams and attach the flashing. The main difference comes with the method in which the material is adhered to the roof. There are three main methods of installing vinyl flat roofing:
The first is referred to as ‘fully-adhered’ installation. This means that the PVC flat roofing material is adhered to the roof deck with an adhesive. It is recommended for roofs with impermeable roof decks, such as those made of concrete. This method of installation also requires ‘mechanical’ installation along the perimeter of the flat roof.
The fully-adhered method should only be used when the ambient temperature of the region is above 40 degrees F. Otherwise, the adhesive will freeze, and the material will not bond to the roof deck.
This method of installation also poses a problem. Since the vinyl material is fully bonded to the roof deck, condensation can form underneath, especially with roof decks with poor ventilation. This will loosen the vinyl roofing, and could blow off in strong winds.
The second form of installation is referred to as ‘mechanical’. This means that it is adhered to the roof deck with heavy duty screws and metal plates. If you live in a high-wind area, this is a good choice for you as this type of vinyl flat roof installation is virtually hurricane proof.
The third form of installation is called a ‘ballasted’ installation. A ballast, when the term is used in roofing, refers to the material used to weigh down the flat roofing material. The PVC roofing material is loosely laid upon the roof deck, and not fastened into place with glue or screws. A ballast (usually a layer of rock) is laid over top to hold the material in place.