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Rising energy prices have prompted a new wave of interest in energy efficiency in the United States. Spray foam roofing provides superior insulation compared to traditional roofing systems and with the Upper Midwest’s harsh weather, spray foam is a must have. The seamless layer of polyurethane foam has zero fasteners, seams and keeps energy locked in. Studies have shown that through gaps and metal fasteners, as much as 38% of the insulating value can be compromised. Benefits include:

  • Eliminate Thermal Drift
  • Reduce HVAC cost
  • Zero Seams
  • Eliminate Condensation
  • Reduce/Eliminate Ice-Dams

The application of spray foam (SPF) will provide better climate control within a building envelope. Better climate control reduces the consumption of fossil fuels, thereby reducing greenhouse gases released into the air.

Generally, SPF shows little sign of deterioration or change in physical properties even after 40 years when properly installed. Studies show SPF roof systems can pay for themselves in about 4 1/2 years through energy savings. Any roof is the primary surface of thermal absorption from the sun and consequently, the roof is the surface responsible for the majority of energy loss of a building.

Since a spray foam roof has the highest R-Value rating of any commercially available insulation on the market, it wasn’t a surprise when a study conducted by Texas A&M University and Ford Motor Company (each has millions of square feet of SPF roof systems) documented that the spray foam roof system actually paid for itself in 4 1/2 years through energy savings. Each 1” of Sprayed Polyurethane Foam provides an R-Value =7. Typically, on most roof applications, a 2” average SPF thickness is achieved providing an R-Value =14 contrasted against a traditional modified or built-up roof system which delivers a much lower R-Value.

Polyurethane spray foam roofs are typically a lot lighter than other roof systems greatly reducing the roof load we see compounded in winter by lots of snow living in the upper Midwest States of Illinois, Indiana, Iowa, Michigan, Minnesota, Wisconsin and others. One inch of spray foam insulation plus 30 mils of an elastomeric coating weight approximately 65 pounds per 100 square feet, as compared to approximately 600 pounds per 100 square feet for a typical conventional four-ply built-up roofing system.

While sprayed polyurethane foam is very light weight, it is strong and will not pack down or sag and can handle foot and construction traffic just as well as other roofing systems. Roofing foam has a compressive strength of almost 50 lbs. per square inch. 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. Wind-uplift tests performed by UL™ have shown that polyurethane foam actually enhances the wind-uplift resistance of the substrate.

Sprayed polyurethane foam forms a seamless insulated roofing system forming a monolithic layer of closed-cell foam. It has no joints or seams that often allow outside water and air to pass through the roofing system into the building structure. Whether a roof is 1000 square feet, 100,000 square feet or larger in size, it will have no seams.

Polyurethane foam is made of billions of minute closed cells which resists the penetration of water and vapors. It must, however, be protected by an elastomeric coating suited for use in that particular environment.

The life cycle cost of a roof is defined as the present value of all the costs associated with the roof from initial installation until reroof. Sustainable systems installed by North Central Insulation preserve natural resources, reduce landfill waste and provide maximum life cycle cost efficiency. Foamed roofs require a minimum of upkeep, creating little waste and have an indefinite lifespan. Waste is reduced through on-site application and packaging that is 100% recyclable. SPF roofs are eligible for LEED points.


  • Temperature insulation performance
  • Life-Cycle cost reduction
  • Eliminates seams and joints
  • Ease of application
  • Zero ozone-depletion

In re-roofing applications, ponding of water may be eliminated by adding an increased thickness of spray foam in low areas. Building up the low areas and sloping the roof so that it drains properly will eliminate ponding water and the additional load factor that is caused by water accumulation.

A material’s R-value is the measure of its resistance to heat flow. (New roof construction the upper Midwest requires a minimum R-value of 22). The way it works is simple: the higher the R-value, the more the material insulates.

Spray foam offers the highest R-value (6.88 per 1 inch thickness), enabling it to provide more thermal resistance with less material than any other insulation leading to decreased energy consumption. Studies show the systems usually pay for themselves in 2.5 to 6 years in energy savings.

Some common roofing materials and their corresponding values for Thermal Resistance ® are shown in the following table.

Common Roofing Materials Thickness
(Highest to Lowest)
Sprayed Polyurethane Foam (SPF) 1.0 6.88
Polyisocyanurate (ISO board) 1.0 5.56
Polystyrene – Extruded (XEPS) 1.0 5.00
Polyisocyanurate Composite 1.5 4.17
Polystyrene Bead Board 1.0 3.57
Cork 1.0 3.57
Fiberboard/Recovery board 1.0 2.78
Perlite insulation 1.0 2.78
Inside Air Film N/A 0.92
Wood 1.0 0.91
Gypsum 1.0 0.60
BUR Gravel N/A 0.34
Concrete 1.0 0.30
Outside Air Film – Summer N/A 0.25
BUR Smooth N/A 0.24
Outside Air Film – Winter N/A 0.17
Vapor Retarders N/A 0.00
Metal N/A 0.00

Because sprayed polyurethane foam conforms and adheres to the substrate and when installed, is a seamless system, it is ideal for flashing parapet walls, roof penetrations and roof mounted equipment, including vents, pipes, stacks, HVAC equipment, skylights, and cooling towers. Many roof leaks are caused by faulty flashings. Sprayed polyurethane foam minimizes this problem.

Spray foam can be used on both new and replacement roofs, whether flat, pitched, saw-toothed, domed or having unusual slopes or configurations. It is also ideal for the spray application to tanks, freezers, coolers, piping, ductwork and various aerospace projects.

Polyurethane foam can be applied to surfaces with irregular shapes and penetrations. Applications include tanks, pipes, cold storage rooms and flotation devices. It’s especially suited for roofing, as many applications can be made over the existing roof. This can eliminate the need for costly tear-off of the old roof. A seamless layer of foam is fully adhered to the substrate–horizontal or vertical–and withstands high wind stresses.

Spray foam has the ability to withstand a structures normal expansion and contraction without affecting the ability to keep the structure protected from the outside elements.

There are no known end service life figures for spray foam and generally shows little sign of deterioration in physical properties when properly coated. The elastomeric coating system which protects the polyurethane foam can be rejuvenated by the re-application of additional coatings after the initial coatings system has weathered after many years of service. North Central Insulation has installed roofs since the early 1970’s that are still performing well!

Spray foam roofing system usually requires little if any maintenance. Minor repairs or modifications can be made by in-house maintenance personnel at minimal cost. Usually all that is needed is a hand caulking gun and a tube of caulking.