Sealant Technologies recommends using open cell spray foam in 5 gal pails because they are easy to transport, manage and dispose of. The open cell spray foam can be designed specifically to integrate into the portable spray foam machine. Open Cell spray foam would be a good choice where larger framing sizes need the greatest R-value per inch possible. Also, because this is a no heat spray foam, it's possible to get into and out the project quickly and without a lot of down time.
Open cell spray foam in 5 gallon pails is a less dense than other types of closed cell spray foam. It has a larger, less compact cell structure. It can be an air barrier as well as a water vapor barrier if it is sprayed at the correct thickness. It is often used in maintenance projects or other home energy retrofit projects, but can be used anywhere where building performance needs improvements.