Problems with spray foam insulation include that the thickness applied can be too thin, installers may miss an air leakage site, installers who overspray or underspray, and the spray foam shrinks and detaches from the framing, states EnergyVanguard.com. However, when properly installed, it can be a very good home insulation.
When the spray foam is too thin, the inside of the house gets hot. Coverage must be even or heat seeps through the thinly insulated areas. When spray foam is evenly applied at the correct thickness, the temperature throughout the house is also even.
When spray foam installers miss an area, the gaps created allow humid air into the room, where it condenses upon contact with a cold surface. It also creates a heat bypass that results in excessive heat loss or gain. The envelope around the house must be completely sealed because gaps compromise the spray foam's air-sealing capability. In a new home construction, a blower door test or fog machine can spot gaps and leaks in the insulation.
When installers fail to locate the building envelope, they may guess or assume its location and apply spray foam where it is unnecessary, which wastes money. Sometimes spray foam from a bad batch during manufacturing can detach or pull away from the envelope or studs, creating excessive heat loss or gain. Spray foam insulation has pitfalls, but when correctly applied it keeps the house comfortable and well insulated.