We are renovating our brick home in Minnesota. We took down the lath and plaster on the outside wall, and found that about 3/4 of that wall is lined with some sort of brown paper, behind it is wood, and then the brick that is the outside of the house.
What is the brown paper?
Also, wondering about insulation. We have updated wiring (though there isn't any in this room on the outside wall). Is using rigid foam insulation alright in insulate brick or is it a bad idea?