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gefstra 10-15-2012 03:04 PM

Insulating a solid brick wall
I live in a solid brick 1920's home in Montreal Canada. I need to insulate, especially in one part of the house as it gets VERY cold in the winter. The plaster walls are typically very cold to the touch from November to March.
I have removed all plaster on the inside of the wall and my plan is to build a cavity with 2x4s for the fiberglass batt insulation that i plan on using.
My questions are:
1-do I build the new 2x4 wall up against the brick or do I leave a small space of about an inch for air circulation?
2- in terms of vapor and air barriers, my plan is to use a high quality vapor barrier on the inside between the 2x4 structure and the new drywall...and for n air barrier I plan to staple tar paper on the structure facing the brick wall. Is that sufficient? is there a better choice for air barriers?

thank you in advance for your help

nealtw 10-15-2012 05:07 PM

When building a wall against concrete we leave the 1" gap and only put house wrap on the back side if there is water expected to come thru the wall. Evan a damp wall should dry out when you insulate and take the heat away from the brick. 6 mil poly for vapour barrier.

gefstra 10-16-2012 07:19 AM

Thanks for the feedback Nealtw; so basically the 1" gap AND the wrap on the back side is NOT necessary for the inside of the exterior brick wall...only the 6 mm poly vapour barrier.
Given the somewhat unevenness of the bricks on the inside there may still be a small gap in certain spots; is it safe to assume that it won't cause a problem later on?

again, many thanks!

nealtw 10-16-2012 07:31 AM

No, we do put the gap in as you suggested earlier. If wood does touch the brick, slide a bit of poly between so the moisture does not transfer.

gefstra 10-16-2012 07:53 AM

Again thanks for your help!

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