Spray foam spray foam insulation is a popular option for high-performance homes, but it comes with a heavy environmental penalty. On this episode of the BS* + Beer podcast, we talk about how the product works and why it comes with such an environmental burden.

The foam is formed when two chemicals — isocyanate and polyol resin — meet at the tip of a spray gun. They react to form a foam that can fill cavities and tight spaces with little effort. The spray creates pockets that prevent air flow and help to keep out heat and moisture. It also provides an effective vapor barrier and can reduce noise.

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It’s important to note that while spray foam can be a cost-effective choice, professional installation is highly recommended. The spraying process and curing time off-gas large amounts of volatile organic compounds, which can be dangerous if inhaled or ingested. It’s generally best for home occupants to vacate the premises during these periods of time.

In addition, many spray foam insulation options require special equipment to install and apply correctly. This can include mobile spray foam rigs and other specialized equipment. It’s also important to choose a product that complies with your building certifications. For example, some green home certifications have banned the use of HFC blowing agents in their insulation products.

Another consideration when choosing a spray foam insulation is the R-value per board foot. Closed cell foam is a good choice for high-performance homes, as it offers better R-values than fiberglass batts. However, open cell foam is more affordable and can offer the same R-values per board foot.