Mason Knowles

SPF is a versatile material, solving many building issues such as energy performance, air infiltration, moisture control, sound transmission, structural enhancement, and more. But even the best product won't work if the job is not done right.

As a sprayfoam industry consultant, I am frequently asked to inspect or evaluate SPF projects to determine if they have been installed correctly. Most often they are, but on occasion I find problems such as off ratio foam, poor substrate preparation, overspray problems, insufficient thickness, and other things that make me scratch my head in wonder. How can a contractor assume that is a proper job?

Most bad jobs are born out of ignorance, desperation or greed. Either the contractor doesn't know any better or he is trying to do a job for too little money.

This article will present tips and information for the contractor to help ensure a quality SPF application. For starters, here is what can go wrong:

Poor substrate preparation — SPF can be installed to a variety of substrates, including wood, concrete, metal, asphalt, foam sheathing, and others. But the substrate needs to be sufficiently clean and dry. By clean and dry, it should be a surface that could be painted (wood moisture content less than 19 percent). If the surface is not sufficiently clean, the foam will not adhere well. If the surface is wet or damp, the A side of the SPF system reacts with the moisture instead of the B side, causing poor cell structure and adhesion.

Cold substrate temperature — SPF applications must be installed within the temperature and humidity levels recommended by the SPF manufacturer. While there is some variation among manufacturers, most SPF systems can be installed to substrate temperatures between 55 degrees Fahrenheit (F) and 190 degrees F. (Note: Some suppliers have developed low-temperature foams that can be installed to lower substrate temperatures.) SPF installed to cold substrate temperatures will form a high-density, shellac-like coating on the surface of the substrate that reduces the adhesive quality of the foam.

SPF

High humidity — High humidity can introduce moisture into the liquid components of the rising foam. The foam cell structure can be affected, leading to poor physical properties. The SPF industry recommends that foam applications not take place when the ambient temperature is within 5 degrees F of dew point.

Improper shipping and storage of liquid components — SPF systems have a shelf life of between three months to six months, depending on the system. This shelf life can be affected by temperature and humidity. Care should be taken by the supplier and contractor to ship and store materials properly. Materials stored in high temperatures can separate, losing their blowing agent to the air. Materials stored in cold environments can become so viscous that the liquid will not flow or mix properly. The A side can develop crystals, causing material blockage and an off-ratio mix. Materials stored in the rain or very high humidity can develop condensation within the drum, thereby contaminating the liquid component. Older materials can separate and absorb moisture-causing problems described above.

Equipment problems — Just like spray-painting and other applications that use pumps to install the product, the application of SPF systems is dependent on the sprayfoam equipment operating correctly. Sprayfoam equipment consists of two transfer pumps that send the liquid components to a proportioning pump. The proportioner heats and pressurizes the liquid to acceptable levels. Then the liquid components are sent in separate hoses to the spray gun. When the trigger is pulled at the spray gun, the material is mixed and sprayed onto the substrate. Each equipment component must operate efficiently for the foam to be installed correctly.

Masking and trimming — Sprayfoam can tenaciously stick to most surfaces and can drift fairly long distances from the point of application. A contractor should have an overspray plan for each job that includes masking or moving items in the immediate vicinity of the application that might get overspray.

Bad design — Sometimes the sprayfoam application is performed correctly, but the foam was installed in the wrong place or at the wrong thickness, or a vapor retarder was added that was not required, or one that was required is missing. Make sure the design is suitable for its intended purpose. Nothing is worse than paying premium prices for a job that is doomed before it gets started.