Every home is different and in some case climate plays a big factor in which product is best for the project at hand. We typically use closed cell about nine times out of ten since we service most of the southeast region of the untied states.
Sub tropic regions such as mid or south Louisiana generally require closed cell due to average ground moisture content and humidity level typically ranging from 80%-100%. Closed cell is crucial in these conditions mainly because closed cell foam is rated as a two pound density foam and it’s cell structure is considered closed which doesn’t alway it to absorb moisture is wetter climates.
The reason this is important is because if you were to use open cell in this same environment it would evenly absorb moisture and basically act as a wet sponge attached to the underside of your home. Over time this can result in floors cupping or buckling. Wood rotting and structural failure. Mold growth as well as attract termites.