EddieWalker
Epic Contributor
Check with the manufacturer of the building before using foam. The ones that I know of will void their warrantee if you use open cell because it traps and holds moisture, which results in accelerated rusting of the metal. Closed cell is usually good because it does not allow moisture into it. Which is also why closed cell is used for dock floats. Cost for closed cell is a lot more the open cell, and it's harder to apply, so you have to be careful of insulation companies that try to push open cell over closed cell. You also get a higher R value with closed cell for the same thickness as open cell.
For a lot less money, I've considered installing metal siding on the ceiling of my shop because my trusses are four feet apart. The metal will easily span that and not sag over time. Then blowing in 2 feet of Attic Cat insulation up there, and then using fiberglass bats in the walls. I did this with my parents garage and the results have been significant. No source of heat or cooling in there, and three garage doors that are also insulated, and in the worse heat of the day, it's still nice in there.
For a lot less money, I've considered installing metal siding on the ceiling of my shop because my trusses are four feet apart. The metal will easily span that and not sag over time. Then blowing in 2 feet of Attic Cat insulation up there, and then using fiberglass bats in the walls. I did this with my parents garage and the results have been significant. No source of heat or cooling in there, and three garage doors that are also insulated, and in the worse heat of the day, it's still nice in there.