ga('create', 'UA-16038215-1', 'auto'); ga('send', 'pageview');
Home | Spray Foam Roofing | Prep for Success
Spray Foam Magazine Discusses the Do’s and Don’ts for Prepping a Roof Substrate Prior to a Spray Foam Roofing System Application

Prep for Success

Spray Foam Magazine Discusses the Do’s and Don’ts for Prepping a Roof Substrate Prior to a Spray Foam Roofing System Application


Sustainability, energy use reduction, prominent R-value to the building, enhanced wind uplift resistance… the benefits of a spray foam roofing systems have been well catalogued over the years to the point where, in many cases, an SPF roof sells itself. Nevertheless, the system is only as good as the contracting company that installs it, and therein lies the level of dedication and expertise that separates the men from the boys, so to speak.

Although the roof system installation largely consists of the application of spray polyurethane foam and a protective coating, the preparation of the substrate is a crucial and equally important portion of the overall project. In order to accomplish a proper SPF roof installation, the contractor must assess the roof beforehand and perform their due diligence throughout the prep process. Not doing so could result in an inadequate substrate preparation that could compromise the integrity of the installation and ultimately produce a roofing system of subpar performance, in spite of the numerous benefits SPF boasts.


One of the most essential requirements for a proper SPF roof installation is having a dry and clear roof surface. A major pitfall leading to an underperforming SPF roofing system is derived from materials installed over a surface that is not 100 percent smooth.  Debris, but more importantly, moisture on the roof can result in an improper yield of the SPF to the substrate, as well as cause shrinkage and generate pinholes in the finished product.

“The first consideration a contractor must adhere to is checking to see if the roof is completely dry,” SPF roofing specialist Manuel Adler of Purefoam Insulation said. “If foam is installed over moisture, the entire project has already gone wrong.”

If sunlight is ineffective in drying the substrate, contractors will have to resort to mopping, using a backpack blower, or a torch – the latter being applicable only in the gravest of situations. As far as debris goes, the crew can either gather the residue in piles using brooms and dispose it in garbage bags, clear the roof by way of a backpack blower, or powerwash the substrate and wait for it to dry before the application of materials gets underway.


Detail work varies from roof to roof. In order to have the best SPF installation possible, surface prep should certainly include repairing any open seams or end-laps using fasteners or plates prior to the SPF installation. Frank Nestle, an SPF and coating roofing specialist and representative from Accella Roofing Solutions explained that if these areas are not reinforced, a potential risk for movement within the roof system is created. This can lead to an eventual split or puncture that would cause the entire roof system to fail.

“If an open seam is not repaired prior to the SPF application, the system might not be strong enough and the possibility of a split happening in the future is greatly enhanced,” Nestle said. “The way to repair these problems varies for with each type of roof substrate, but generally fasteners and plates pull the protective membrane down and tie it to the roof deck.”

As far as priming the roof before the application goes, the type of substrate and the spray foam’s application specifications are the major determinant factors to assess whether a primer coating is needed. For example, stainless steel substrates will typically need a primer since they require more adhesion for the foam to bond to the substrate. However, if the substrate or the spray foam specifications don’t require the use of a primer, it is not a good practice for a contractor to apply it anyway, as it would be a waste of time and money.


Overspray can be hazardous and potentially problematic for the contractor if severe damage is caused to the surrounding area of the roof. Therefore, the savvy roof contractor needs to ensure that everything that can be done to mitigate overspray is done.

If a contractor is spraying during windy days, a red flag is automatically raised. There should always be a crewmember monitoring the wind direction so that the crew can assess whether it is safe to spray or not. Prior to any foam or coating application, the contractor should make sure to clear parking lots from cars and foot traffic, that all moveable objects on the roof are temporarily moved, and that all immovable objects are properly masked off.

“A contractor being careless and spraying during high winds is a huge black eye for the industry,” Nestle said.  “It is important for an SPF and coating applicator to know that applying the materials amidst a light breeze is fine, whereas attempting to apply SPF or coatings during high winds is unacceptable.”

During the application, the crewmembers should use windscreens or spray shields to further mitigate overspray.


A self-respecting contractor should never allow his crewmembers to be in harm’s way during a roofing project. According to OSHA’s fall protection requirements, a crewmember that is working on a roof that is higher than six feet from a lower-level roof needs to be wearing a safety harness or some type of fall protection when working along the roof edges.  Additionally, the crew should install perimeter flagging along the roof edges so that crewmembers are fully aware when they are close to the edge. The only instances in where SPF roofing crewmembers are exempted from these safety guidelines are if the roof has parapet walls along the edges that are 39 inches tall or higher or if the ground or lower-level roof below them does not exceed 6 feet.

“Workers need to be protected by the companies they represent, so the company is directly responsible for educating them about safety guidelines,” Adler said. “Safety should be a number one priority before and during the project.”

Close Bitnami banner