Contractors who install spray polyurethane foam insulation put themselves at risk if they do so in homes without a plan for mechanical ventilation. Most spray foam insulation, when properly installed, acts as an air barrier. When you use it instead of the fluffy stuff (fiberglass, cellulose, cotton), a house will be more airtight, and that’s good. However, when a house is airtight, volatile organic compounds (VOCs), water vapor, odors, radon, and other stuff you don’t want to immerse yourself in make the home’s indoor air quality worse. How do you solve this problem? Source reduction and separation would come first, but airtight homes need mechanical ventilation.
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