Polyurethane spray foam insulation is a sustainable choice for both homes and commercial buildings. Once cured, it is a safe product and you don't have to worry about chemical exposure. You do have to be careful, however, that the spray foam is fully cured before you have contact with it or manipulate it. Just because the foam looks dry does not mean that it is fully cured.
The word "curing" refers to the process which takes place after the chemicals have reacted to produce the initially wet, airy polyurethane spray foam insulation. Initially, the foam is highly adhesive and sticks to the surfaces upon which it is sprayed. Over time, it cures, or hardens. This is a process that occurs over hours or days, and between the soft and hard stages, the spray foam is sticky and tacky. At this middle stage, it appears hard, but it is not fully cured and still contains unreacted, unstable chemicals.
Different spray foam products cure at different rates. Most manufacturers estimate that it takes between 23 and 72 hours for the substance to fully cure. This estimate applies to the more common, two-component foams that are used in many professional spray foam applications. One-component spray foams, which are generally sold in small quantities in 12 or 24 ounce cans, only take between 8 and 24 hours to cure.
When applying spray foam, it is important to take the curing time into consideration when planning the process. In high humidity or high heat, and in situations where very thick layers of foam have been applied, curing may take up to three days. Applicators and building owners must plan accordingly for re-occupancy of the building.
Contact NCFI Polyurethanes for more information about the curing process of spray foam insulation.