Bricks, Masonry, Asphalt and Concrete - Insulating a brick home

We have a home with 3 course brick walls and concrete floors, circa 1910. There is a 2" air space between the outer 2 courses and the inner course of brick. The walls are plaster applied directly to the brick. I know the air space is for condensation. We live in So. Minnesota, with relatively cold, dry winters. The house is one big thermal bridge. I would like to insulate that 2" air space using tripolymer foam, which is a phenolic foam that is fully expanded at the time it leaves the application gun. The company has done many of these homes. My question is this: Will foaming in that air space cause problems with the brick? Will the moisture moving through the brick freeze and cause the brick to fail? The bricks are quite soft. C.P. Chemical, the maker of tripolymer, tells me that the foam shrinks slightly and should allow condensation to run down the wall of that air space. Any help on this would be greatly appreciated. Thank you.

Single wythe block wall construction is very similar to what you've described. Hot and cold is transferred to the inside faceshell through the webs. The use of a foam in the cavities of a C.M.U. will greatly increase the R factor of the block... and is fantastic at filling in all the minor pinholes in the mortar joints caused by sloppy workmanship. Your walls have survived nearly 100 years already. I personally don't know if the foam will hurt the brick (you said they are soft mud) and regardless of what's behind them... the face brick will continue to absorb moisture... and will always run the risk of "face pops" if they freeze. The foam will help with the insulation R factor... but I've never heard of it shrinking. We have worked with The FOM Company on several jobs in the past... and theirs does not shrink.

Hopefully, someone else more knowledgeable will add to the comments.

Good luck.

www.southsidebuilders.com

the walls are much different than a modern CMU block wall with a brick veneer where they install foam between the two. The unknown factor is how the insulation will affect the water vapor as it migrates through the wall system. It will certainly freeze faster than it now does. Thanks.

should have read my own post.