Which is better for residential walls, 1/2 pound or 2 pound foam?
Both are excellent wall foams both give you thermal and air barriers even though the 2 pound gives you added moisture and vapor barriers. It becomes mute because the State of Wisconsin still requires a separate vapor barrier. The question becomes is what size thickness of wall do you have a 2 x 6 or 2 x 4 wall. A 2 x 6 wall full filled with 1/2 pound will cost the same as 2 1/2″ of closed cell, the R-value for 5 1/2″ of 1/2 pound would be around 19 where it would be around 17 for 2 1/2″ of close cell. However if you have 2 x 4 walls you will have an R-12 with 1/2 pound and an R-17 for 2 1/2 inches of 2 pound. Many recommend 1/2 pound for cathedral ceilings because if your roof leaks it will penetrate through the 1/2 pound foam letting you know you have a roof leak, with the 2 pound it will trap the moisture not letting it through and possibly rotting your roof. An advantage of 2 1/2″ of closed cell is you can still fish electrical in your walls at a later point if you have a 2 x 6 wall
