Polyurethane can be dangerous. Not only is polyurethane stringy and odorous, but it also is toxic and potentially hazardous to your health.
So why bother with polyurethane? Because polyurethanes are the only sealants that can stand up to abrasion. Forget that polyurethanes are paintable, flexible, and weather resistant. There is almost nowhere in residential construction that a safer product cannot be substituted -- except for those high-traffic areas. But if you need to seal joints on a floor, on a driveway, or in a garage with frequent foot or vehicular traffic, break out the rubber gloves, the respirator, and the polyurethane sealant.
Polyurethane spray foams cure rigid and have an R-value up to 4.5 per in. But polyurethane foams are tricky to use because they expand as they cure. Polyurethane foams come in low, moderate, and highly expanding formulas, but even minimally expanding polyurethanes grow
up to 300% before they cure.
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