Yes, foam is good for residential and commercial construction practices.  The two main types of spray foam are closed cell and open cell foam.  The closed cell foam is a vapor barrier whereas the open cell foam will allow air to pass through.  Closed cell has a better R-Value per inch of application but is more expensive to install.  So where is the common ground?  We have found that a hybrid approach works best for us and keeps the costs down.  In the 2×6 cavity, we spray a 1/2″ of closed cell foam on the back side of the sheathing and then blow in fiberglass batt insulation for the rest of the 5″.  The spray foam creates a great seal to repel any air infiltration and the blown in batts fills the gaps and delivers a great composite R-Value for a 2×6 stick framed wall.  It’s a great idea to also spray foam your band board in a crawl or basement.  The investment will pay dividends year after year and is well worth it.

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