Polyurethane foam insulation has attracted considerable attention in recent years as a green, affordable, and highly effective building material. This material is mixed on site and blown into (and onto) the walls, roof, and other supports of a structure to apply an even insulation surface and create a tight seal. Its design allows it to be spread into even the smallest cracks, and as it expands and hardens, it creates a tight, water-resistant seal that provides a very high insulation value, useful for cold regions like Denver where heating and cooling prices add up, all at a very affordable price.
Sounds like a green building dream, right? Spray foam insulation has been used in the construction of a number of buildings that meet incredibly high green building certification standards and the industry touts how environmentally-friendly this product is, but is it? And how healthy is it for people who work with it, as well as those who work and live in buildings with spray foam insulation? While it was initially believed to be quite safe, the evidence on that is changing.
Here's how it works: two mixtures, known as Side A and Side B, are sprayed on site by trained installation personnel. Before they combine and cure, they contain a number of compounds known to be hazardous to human health, which is why anyone on the premises needs to wear appropriate protective gear, including solvent-resistant gloves, a respirator, and a suit. Homeowners and others should be kept out of the site if possible, and if they need to be there, they need protection.
For anywhere between seven hours and three days, depending on manufacturer recommendations, people should not be in the area without protection. This time allows the product to fully finish curing and expanding, and during this period, it may offgas. Theoretically, spray foam insulation is "relatively inert" after this stage, but is it really?
For one thing, there can be problems with installation. If the mix is not applied properly, toxic chemicals may remain present, offgassing for an extended period of time and causing environmental illness, including respiratory diseases. For another, if the insulation is trimmed, drilled, or otherwise modified too soon, this can also cause the proliferation of toxins. These known issues indicate the teams installing spray foam installation during a home remodel or green home retrofit need to use extreme caution, and must be well-trained when it comes to working with these substances.
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