Spray polyurethane foam (SPF) roofing systems can be great roofs, but like any roof, it has its disadvantages. This particular roof is not a perfect fit for all roofs. There are many factors that determine which system is the right fit. Before investing in any roof system, it pays to examine your options and research the pros and cons.
The standard SPF roof consists of four components, the substrate (often the roof deck), the SPF layer, the base coat, and the top coat. While SPF isn’t exactly new to the low-slope roofing industry, many professional roofers are hesitant to install this type of roof.
Due to the installation requirements for SPF systems, installation can only occur during specific weather conditions. The manufacturers that issue the warranty requirements are who stipulate the range of outdoor temperatures and humidity levels that roofing companies can install their specific systems. If the roof is installed outside of this window it can negatively compromise the integrity of the roof. SPF foam can blister, bubble, and develop holes when installed outside of specified conditions. The optimal climate for applying SPF roofs is warm, dry weather with little to no wind.
While SPF offers decent R-value when correctly applied, its thermal resistance is only as good as the worker controlling the spray foam mix. Inexperienced roofers often leave uneven bumpy spots on the roofs, which can not only decrease the R-value, but create potential puddling areas that may become a drainage hazard in the years to come.
Fumes emitted during the spraying process present a potential inhalation hazard. Masks are recommended when installing SPF roofs. Rooftop HVAC units should be shutdown during spraying. SPF’s key ingredient, isocyanate, is hazardous when inhaled or when it comes into contact with the skin. Strict compliance with manufacturer and OSHA safety regulations is required. Likewise, the spray is lightweight and prone to sticking to anything it makes contact with. Even a slight breeze can deliver overspray to nearby structures. Extreme caution is advised when applying spray foam.