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What is the best way to insulate a 4” wall cavity on the interior side of a stone house?

DJ Tejeski | Posted in Green Building Techniques on

I am working on a stone home in Philadelphia PA that was built in 1920. The exterior walls are 20” of stone with 4” studs on the interior with wood lath plaster.
The framing is balloon type . The studs do not have sheething. The concern is if we fill the 4” void with fiberglass insulation or cellulose the stone will pull moisture into the filled cavity and create mold and mildew.

Any ideas
Don Tejeski

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  1. GBA Editor
    Martin Holladay | | #1

    Proceed with caution. I wouldn't recommend installing any type of insulation unless you are willing to demolish the plaster and lath.

    Most experts would advise that closed-cell spray polyurethane foam would be the best choice of insulation, but even with spray foam it's best to approach such a wall with caution. There are a lot of variables, and the escaping heat is currently helping to keep the stonework dry.

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