As a roofing expert, I have seen and used all the different roofing systems that are available. I do this according to what clients want and to their budget. However, of all the roofing system alternatives, there is one that is always my topmost recommendation: spray polyurethane foam.
Spray polyurethane foam, commonly called SPF in the industry, has been used for roofing and insulation for almost 50 years. Foam roofing systems have stood the test of time and have been proven to be durable, reliable and very affordable. Building owners who have made this choice as well as independent studies have established this beyond a shadow of doubt. As long as they are well maintained, foam roofing systems can last indefinitely.
The greatest advantage of SPF, though, is its energy efficiency. It facilitates energy savings of about 30% or more compared with other roofing systems. The cost of putting up an SPF roof pays for itself in less than 5 years through energy savings alone. The foam has an R-value of 7.14 per inch of thickness. This enables it to provide higher thermal resistance with less material than every other kind of roofing insulation. This is thanks to SPF’s superior insulation properties.
Spray polyurethane foam is a mixture of two components: polyol and isocynate. The two are pushed into a proportioner, which heats them and then pumps them into a spray gun. Here, they are mixed and then sprayed onto a roof in liquid form so they form one continuous layer that is seamless, solid and stable.
For proper application, SPF should go onto a clean surface. There should be no contaminants, such as oil or dust, or else it will not adhere to the surface as it should. It should also be applied in accordance with local building codes. After application, a protective elastomeric top coat is added. Typically, this coat is applied as a spray as well.
Apart from excellent energy efficiency, foam roofing has a number of advantages over conventional roofing methods because of the following qualities.
The foam can be sprayed onto virtually every kind of surface. This eliminates problems with roofs that are irregularly shaped and those that have protrusions.
Polyurethane foam is applied in liquid form so it becomes a single, monolithic layer covering the whole roof. There are no joints and no seams, which are where most leaks in traditional roofs come from.
Foam roofing weighs about 50 pounds per square. Compare this 800 pounds, which is what a built-up roof weighs, and the 100 pounds that goes into single-ply roofs with ballast.
- Thermal insulation
SPF has superior insulating properties to those of other roofing options available for commercial buildings.
Foamed roofs are very undemanding when it comes to maintenance. There is very little waste in putting one up, and their lifespan is indefinite.
SPF is excellent for various waterproofing applications. It makes a roof completely impenetrable to water. SPF is made up of a billion closed cells which act as a highly efficient air barrier that ensures that moisture cannot infiltrate a building. This minimizes problems with dew, which if left unchecked can lead to water condensation inside a building; this is how mold and mildew form. Moisture infiltration is a leading cause of building deterioration.
Should the uppermost layer of a foam roofing system get damaged, it will still not leak because of the underlying foam. This is evidenced by the incident where the Superdome in New Orleans was damaged in a severe hailstorm, which left numerous hairline cracks on the top coat. However, there were no leaks even though the roof went without being repaired for more than 10 years. If water had penetrated through all the layers of foam, it would have been isolated only to the part where the membrane was penetrated. It is easy to repair minimal penetrations using elastomeric caulk, which will restore the structural integrity of the system.
The problem of water ponding is quite common with other roofing systems. When re-roofing with SPF, it is very easy to add thickness while spraying to ensure that water will drain off the roof properly. This also takes care of the problems of an increased weight load caused by water accumulation.
Apart from roofing, I use SPF for insulation and protection for a number of other structures. I use it to insulate tanks, freezers and other structures in the wine industry, oil industry and chemical processing plants. It has yet to fail me as a roofing system or as an insulator in these structures.