Spray Polyurethane foam (SPF) roofs are a roofing material that are still greatly misunderstood and under-utilized today. The value provided by an SPF roof is far superior to nearly all other roofing methods, and yet it hasn’t broken into the “mainstream” roofing industry as it should have. Polyurethane foam has been used in roofing applications for over 40 years, and it is just now starting to gain traction in the market.
What is an SPF roof?
An SPF roof is constructed by mixing and spraying a two-component liquid that adheres to the roofing substrate and forms a base roof system. Once the initial foam is applied, a protective surface is applied to the foam to protect it from the elements.
The two components that make up the foam are isocyanate and polyol. These components are applied using transfer pumps that heat and transport the materials at a one to one ratio. The components are mixed at the spray gun directly before application, and are then sprayed and applied to the substrate.
What goes on top?
An SPF roof is a two part system, the first being the rigid SPF insulation explained above. The second part is the protective surfacing, which is commonly a spray applied elastomeric coating. These coatings can also be hand or roller applied. This elastomeric coating provides weatherproofing, UV protection, mechanical damage protection, and increased fire-resistance. There are many different types of coatings available for an SPF roof, we recommend a silicone coating.
Many times, mineral granules or sand are broadcast into a recently applied, uncured coating to increase the aesthetic value and surface durability of the roof. These granules can be many different colors, and also provide improved performance of the walking surface of a roof.
Polyurethane foam can be installed in various thicknesses to provide slope to drain or meet a specified thermal resistance (R-value). The chemicals that are used for an SPF roof are specially manufactured to perform in various temperature ranges. Some foam components can be changed to allow application in certain conditions and to certain substrates.
For more information on spray foam roofing and what it can do for you, check out the NRCA’s website.