Roofing applications often fail because of the multiple seams that are created because of the large amount of surface area of a roof. Every penetration that goes through a roof is a possible leaking point that can go unnoticed for years before the damage is seen. There is one roofing application that has no seems at all, and is unlikely to leak ever. A spray foam roof.
Spray Foam Roofing Material
Spray foam roofing material is a spray application that expands to form an insulation barrier, typically used as interior cavity insulation for walls and cathedral ceilings. Roof spray foam is applied to the exterior surface of the roof in a three inch layer. This type of spray foam is a higher density (around 3 lbs per cubic foot versus 1.8-2 lbs per cubic foot) to take the abuse of rain, snow, hail, and other wind conditions. Because the foam is applied as a spray, the entire roof surface is one monolithic slab of adhered spray foam. This adds significant rigidity, insulation value, and protection to the roof.
Preparing The Roof Surface
In order for spray foam to stick to a surface, it has to be clean of debris and dirt. Power washing the roof surface and removing any loose or damaged roofing is needed before the surface be be properly foamed. The roof flashings should also be inspected and changed out before the spray foam is applied.
Spraying the Roof Surface
The roof surface must be sprayed evenly working from the top to the bottom of the roof. This is done so that the drainage is not affected. If the roof surface is a flat roof, the spray foam can be used to shape the roof for proper pitch to surface drains and scuppers. The roof will need at least 2 coats of spray foam. One coat application will be applied over the entire roof surface with the second coat to follow.
Protecting the Spray Foam
UV light breaks down spray foam and will turn it to dust if left exposed for long periods of time. The entire surface must be covered wit an elastomeric coating, which is an extremely flexible and durable paint. This paint lasts 15 years before it needs to be re applied. The process is very simple. Apply a thin coat of paint to the surface of the roof with a paint sprayer. Using a roller will work, but the coating will not last as long. Go over the entire roof surface with the thin coating of elastomeric paint and let dry for 2-4 hours. Apply a second coat with the sprayer. It is important to work in thin coats as a thick coat will crack negating the purpose of the protective coating. This should be the only maintenance item for this roof. As long as this coating is applied and reapplied every decade or so, this type of roof can last a lifetime.