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Community and Q&A

Brick building insulation

Robert Bowers | Posted in Energy Efficiency and Durability on

What is the preferred and proven safe product to insulate the approximate 2″ cavity between the lath and plaster walls and the brick facade?

What items do I need to investigate / insure before insulating?

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  1. GBA Editor
    Martin Holladay | | #1

    There is no simple answer to your question. What's your climate?

    In almost every climate zone, building codes call for more than 2 inches of insulation. So the cavity isn't deep enough to do much good.

    Insulating a brick wall makes the bricks colder, and therefore wetter. In some cases, insulating a brick wall makes the wall more vulnerable to freeze/thaw damage.

    It takes an experienced building science consultant to assess the risk factors in such cases. Do roof overhangs protect the walls from rain? How cold does it get during the winter? Are the bricks and mortar very absorptive or only somewhat absorptive?

    You might want to check out these pages:

    How do I "best" insulate my 8" brick exterior wall 1 1/2" air gap wall?

    Insulation Retrofits on Old Masonry Buildings - Building Science Podcast

    Old Brick House and Little Money

    An article on the topic by John Straube

    Lstiburek's "Thick As a Brick"

    In addition, I strongly advise you to read "Insulating Residential Masonry Buildings In Cold Climates" by Chris Benedict (in Home Energy magazine, March / April 2010).

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