Spray Polyurethane Foam (SPF) adheres to just about every traditional roofing material so it can be installed over concrete, wood, steel, and most existing roof systems. This saves on the expense of roof removal and landfill fees, and is considered to be more environmentally friendly. SPF Roofing installers can spray apply a tapered roof system with the foam, which eliminates the need for costly tapered insulation systems. The cants and vertical wall terminations are also spray applied making them an integral part of the roof system and minimizing additional component costs and flashing materials.
Sprayed Polyurethane Foam is applied as a liquid using plural-component spray equipment to fill cracks and crevices. It then expands approximately 30 times its original liquid volume to form a hard, closed cell monolithic roof surface. This seamless total roof covering helps to significantly reduces the possibility of leaks.
The Polyurethane Foam dries within seconds after applied to the roof surface. Its expansion results in a weather tight roofing membrane that is fully adhered to the substrate. Because of polyurethane's lightweight it adds little additional weight to the structure and is often used in remedial applications.
Polyurethane Foam has a history of more than 35 years as a maintainable roofing medium. Polyurethane Foam adds excellent insulation value to the structure and utility bills can reflect the difference.
Once the SPF has been applied to the proper thickness and finish specifications, a protective layer of elastomeric coating or gravel is applied. This protective layer produces a durable weather resistant surface and that can be walked on for normal maintenance.
Foam roofs are very durable and can handle foot and construction traffic just as well as other roofing systems. They are still susceptible to damage from dropped tools just as any other roof but the damage is more easily seen and can most often be repaired with some simple polyurethane caulking. Spray Foam roofs have extremely high adhesive characteristics and often demonstrate the strongest resistance to high winds and wind-uplift. Spray foam roofing systems have performed extremely well compared to traditional roof systems in areas of high wind, tornados and hurricanes.
Most SPF roofs have densities ranging from about 2.5 pounds per cubic foot to 3 pounds per cubic foot. Density of SPF is important when it comes to strength and thermal resistance. Obviously, higher density means increased strength and higher R-value. Three-pound density foam has a compressive strength of about 50 psi and an R-value of 7.14 installed and 6.86 aged (these numbers may vary slightly depending on the foam manufacturer).
Here's an example of how well a good SPF roof insulates. A school district in southern California had recently installed some new, one-room relocatable classroom buildings. During the late spring and early fall, these classrooms were using their air conditioners an average of 50 minutes every hour. The school district installed foam roofs on some of these classrooms in order to see if it would provide an energy savings. The roofs consisted of three-pound density foam, 1.5 inches thick with an acrylic coating system. The air conditioner usage was cut down to fifteen minutes every hour. That's a fifty-eight percent savings on energy costs.
Does this mean an SPF roof pay for itself? Absolutely! Texas A&M studies indicate that an SPF roof in Texas and other southern climates can pay for itself in approximately four and a half years.
If the coating for an SPF roof is properly maintained, then an SPF roof can last a very long time. Every ten or fifteen years, depending on the type and amount of coating installed, the roof will need to be cleaned, primed, and recoated. If this is done, then a quality SPF roof could last 50 years or longer.
As with all other roof systems, cost depends on several factors. Some of which include building accessibility, condition of the existing roof structure, complexity of project, foam thickness, foam coating system, and geographical location. Costs may start at about $2.50 per square foot for a less expensive system and go up from there.
Once the SPF has been applied to the proper thickness and finish specifications, a protective layer of elastomeric coating, or even gravel covering is applied. This protective layer produces a durable weather resistant surface and that can be walked on for normal maintenance.
ENERGY STAR qualified roof coating products reduce the amount of air conditioning needed in buildings, and can reduce energy bills by up to 50%. The Cool Roof Program defines certain standards for reflectivity, and maintenance of reflectivity, in roof coating systems. These light colored roof coatings reflect the suns heat and UV rays and often lower the temperature of the roof by up to 100 degrees.
Installation of Spray Polyurethane Foam (SPF) involves different procedures based on the existing roof structure. It is important to be familiar with all state and local building codes to assure the appropriate materials and procedures meet the necessary requirements in your area. Once determined that the roof structure and roof deck is prepared and ready for Polyurethane Foam, high-pressure spray equipment used by trained professional crews can cover thousands of square feet per day.