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  1. user-2310254 | | #1

    Just to be clear, your sill plate is below grade on three sides of the house, correct?

  2. TWslide | | #2

    Afternoon Steve -

    The top of the block walls are all below grade, to some extent. The fourth Side with the breezeway is the least below, roughly 3 inches. All of the tops of the rim joists are above grade on all four sides, albeit minimally in spots. Unfortunately, there is no sill plate.

  3. user-2310254 | | #3

    Sorry, I should have read your links before posting. It seems your brick walls are structural.

    Do you have a forced air system or something else? I ask because it's possible for a system fan to depressurize a home and that can make smells more noticeable. Similarly, sometimes homeowners will install a ventilator/dehumidifier to slightly overpressurize a home and push odors out. Of course, you want to make sure you don't have an underlying problem.

  4. TWslide | | #4

    No problem, the link provided was in reference to the smell and my thought process. I do not believe the brick is structural, as it is one Wythe and no wood comes in contact. The rim joist maintains the 1" air gap.

    Yes, my home has a forced central air system, that had been installed in the 90's. This is our third summer in the home with the forced air and dehumidifier (in basement) and the first time we have had this issue. While we have installed new insulation in the attic and a new roof, the only difference in the basement is the XPS.


  5. user-2310254 | | #5

    I think I understand. No sill plate with exterior walls bearing on the subfloor. Like this photo.

  6. TWslide | | #6

    Yes, Thank you for the photo! As you can see, the cavities in the block are open to the inside and mine also has an opening on the other side of the rim joist. While the A/C may be pulling air from the walls as the house was tightened up, my concern is with the way to properly insulate this area. I pulled off some of the foam that had been installed and the bottom of the rim joist and joists has roughly 1/4" of moisture. I had no noticed this before i installed the XPS.

  7. Expert Member
    BILL WICHERS | | #7

    You may need a capillary break. If water is wicking up from the block foundation, that will wet the rim joist and the bottom edge of the floor joists as well.


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