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Spray Polyurethane Foam (SPF) is a spray-applied, insulating, closed-cell foam plastic that is installed in liquid form and then quickly expands into a permanent, solid, insulating material. As the foam solidifies, it expands at many times its original size. Spray foam can be easily adjusted based on the requirements for the application and has many different physical properties and applications.


SPF benefits


  • Leak-free monolithic seal over your entire roof deck
  • Self flashing roof system with no transitions, joints, cracks, or fasteners that can leak
  • High insulation value to provide significant energy savings
  • Strong adhesion and wind uplift resistance
  • Applied directly over asphalt, shingles, built-up roofs, metal, and wood, eliminating expense of tear-off



Polyurethane foam can be applied over almost any substrate. In most cases preparation simply involves cleaning and securing the roof surface. SPF roofing systems are lightweight and add little to the existing structural load. In fact SPF usually weighs less than the ballast that has been removed from an existing roof.


Preparation for different roofs:


  • Built-up roof with ballast – removal of ballast with a commercial vac
  • Built-up roof without ballast – power washing or blowing the surface
  • Metal roof – power washing the roof surface
  • Single-ply roof – removal of membrane or fastening down the boards



Polyurethane foam is sprayed onto the prepared roof surface in two components (a polyol and an isocyanate) that when mixed expand to approximately twenty times their volume to form a seamless layer of rigid closed-cell foam. Within minutes this foam can be walked on and cures to 90 percent of its full strength in about four hours.


Because polyurethane foam adheres to most surfaces, horizontal or vertical, it creates a fully-adhered, self-flashing, monolithic roof surface, with none of the critical failure points of most roof systems (seams and penetrating fasteners). The thickness of the foam can be controlled to create positive drainage where ponding was previously a problem.



Once the polyurethane cures, a layer of an elastomeric coating is applied to further protect the roof from UV light, weather, and normal wear. Elastomeric coatings are almost always white or light-colored, with the most common materials being silicone and acrylic, other materials include urethane, butyl rubber, and polyurea. Physical properties, application equipment, installation procedures, and pricing vary from material to material. The coatings can be single or multi-component materials that are spray applied in two stages: basecoat and topcoat. Sometimes, the spray application process involves priming the foam surface or embedding granules (broadcasting) onto the topcoat.



The finished roof should require little or no maintenance, but silicone caulk can repair most damage to the roof surface. Provided there isn’t any significant physical damage, just normal wear-and-tear, maintenance usually involves cleaning, priming, and re-coating the roof surface.  A polyurethane foam roof can be repaired and re-coated indefinitely. Many foam roofs have been in service for over thirty years.


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