Open cell vs closed cell for a 2×6 wall cavity – which do you prefer?

We use closed cell for anything below grade or on exterior walls in cold climates. Open cell is great for interior partitions for sound but not for an exterior wall in zone 5. Vapor drive in winter will push moisture into that open cell.

Down here in Texas I use open cell on just about everything – walls, ceilings, you name it. But zone 5 is a different animal. Go closed cell if I were in your shoes.

Open cell is around R-3.7 per inch, closed cell runs R-6 to R-7 per inch. For a 2×6 wall (5.5 inches), open cell gives you around R-20, closed cell gets you R-33 if you fill it completely.