What is the difference between open and closed cell foam insulation?
Open cell foam is usually more suitable for residential applications for several reasons. Open cell foam is more flexible than closed cell foam. When the framing members expand and contract with the weather, open cell foam will flex with the wood, but closed cell foam will get hairline cracks where it was connected to the framing members because it is not able to flex. Another difference between open and closed cell foam is that, when used at the roof rafters, if a roof leak develops, the closed cell foam will not allow the water to weep through the foam because it is a vapor barrier. This can lead to rotting of the roof deck before the roof leak is ever discovered. Open cell foam is not a vapor barrier, so it allows the water from the roof leak to weep through the foam to the space below. After the roof leak is repaired, the open cell foam can be allowed to dry and its thermal properties return, unlike other insulations that must be replace when they get wet. In addition to these diff
