My sister has a 100 year old or older home over a wet and damp crawl space on an island which has high tide and rain water flooding of streets an crawl spaces. A sump pump runs all the time. The home is recently gutted. The wood floor joists which are a mix of 2 by 10s and 2 by 8s spaced mostly about 19 inches apart, are not rotted, but some are loose in the brick pockets. The exterior brick walls have a stucco over them on the outside of the house. Some interior walls have plaster and new stucco over them inside the house. The plastered walls have moisture and wet spots always forming on them and that efflorescence stuff. The exposed brick never has a moisture problem. I told my sister to expose all the interior wall bricks to the open air, but her husband had already paid a mason good money to fix the old plaster with stucco which really does not dry or stay dry in some places. The mason has no solutions to the wet patches.

The exterior brick walls are being framed for electrical and insulation. By local code the exterior brick walls need to have R13 insulation. But my research shows that is a problem for the moisture. The bricks will not dry out and the insulation will get wet and this leads to rot of the floor joists in the brick pockets and deterioration of the brick and mortar as well as the wood framing especially around the windows which the house had a big problem with.

My questions are as follows:

  1. What insulation should the exterior brick walls use? If the town insists on R13, what kind is best in that damp interior wall against the bricks? How can the insulation and wood framing be protected from moisture? Also should all drywall be a damp area rated drywall like the kind used in basements and bathrooms?

  2. The damp moisture plagued interior walls which run against the neighbors house on both sides (the house is a row house) have always been a problem where they are plastered over. My sister wants them to be furrowed out and then drywall put up. What is the best way to put the wood furrows and not expose them to moisture? Perhaps felt/tar paper on the wall first then furrows, or ridged low rated insulation taped at seams across wall, or ridged low rated insulation or tar paper just at the wood furrows, (but not over the entire wall) and then drywall? In the last case the wall would have more breathing room, but the wood still protected.

  • In modern construction, the brick is not structural. The home has an exterior sheathing, a house wrap (like tyvek) to block moisture and drafts, and then the brick is supported with a small airgap off of the wall. There's also a second layer on top of the house wrap that I've seen installed by masons, possibly a tar paper. Then, at the bottom of the brick wall, weeping holes are placed every few feet. The idea is for the bricks to have air on both sides and any moisture to travel out through the weeping holes, rather than into the home.
    – BMitch
    Commented May 26, 2013 at 19:29
  • 1
    There seems to be a serious moisture problem and I would try to figure out the source of all this moisture. There always be some water vapor traveling through brick, but from your description it seems like there's just too much water. Could it be that there's a problem with roof or gutters which let water run over the masonry?
    – Vitaliy
    Commented May 28, 2013 at 22:49
  • I absolutely agree , nothing should be done until the the moisture problem is identified and steps taken to eliminate or mitigate it. Otherwise you will have spent more " good money" for nothing and will have to spend more good money to continue putting band-aids ( stucco or ? ) over problem that has not been resolved.
    – Alaska Man
    Commented Feb 4, 2017 at 4:44


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