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Sealing & insulation of rim joints (brick house)

giantsean | Posted in General Questions on

Hi. I have a 1951 cape which is mostly brick/block except for this room in question, built in 1980, which is brick veneer with a wood frame. There is a bedroom above it and a sided wood dormer begins at the top of this room on the side with the fireplace, and the other side w/ the bay window is the eave of the roof. I am working on replacing the ceiling and noticed that the rim joists only have fiberglass insulation packed in,which I’m sure was typical for the time. Since these areas are poorly sealed, I found evidence of various fauna which had made their homes at some point, such as squirrels, mice, and bats.

The construction seems fairly typical and unlike the rest of the house does not have any structure sitting in masonry. I was thinking of simply sealing off the joist spaces with polyiso and foaming around the perimeter to air seal, then packing fiberglass in front. I did read a bit on brick house sealing on the site and for this part of the house at least it seems the way to go, but want to make sure I’m on the right track.

You can see from the detail pics I foamed a bit where animals had chewed in or otherwise had enough space to enter. Please ignore the rot in some places in the pics as it was part of a problem w/ the chimney on that side which has since been addressed. The bricks you see are part of the fireplace structure, not the brick veneer. I attach these more to illustrate the spaces with which I’m dealing. Thanks for any input!

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  1. GBA Editor
    Martin Holladay | | #1

    These rim joist areas need to be insulated with rigid foam insulation or spray polyurethane foam insulation. Whichever material you choose, you need to pay careful attention to air sealing.

    Here is a link to an article which will provide guidance: Insulating rim joists.

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