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Water/moisture proofing

user-7542295 | Posted in General Questions on

Hi all –

I purchased a split level house in New Jersey last year and the downstairs part of the house is about 1-2 feet above grade.  This June, I experienced a moisture/mold issue on the drywall on the exterior facing part of the room; this looks to have been an issue for a while but I was unable to see this due to wallpaper and furniture that was blocking this. 

My insurance company assisted in providing remediation and now this room is down to the studs.  During this incident, I also noticed that the stucco/parge coat on the exterior CMU was in poor shape as well.  As a precautionary measure, I’ve done the following:

1.  Excavated down to the footing of the foundation
2.  Removed old stucco/parge coat
3.  Cleaned CMUs
4.  Installed Grace Bituthene System Waterproof Membrane which covers the foundation wall with the exception of about 1-2 feet above grade
5.  In the process of redoing mortar joints and patching any exterior damage on CMUs

I’m looking building a barrier or system to prevent or reduce the amount of moisture that is being absorbed in the above grade CMUs into this room.  I’ve read a ton of different ideas on this including:

1.  Applying water proofing paint/solution such as Drylok or Stryo Tuff II on exterior and interior of CMUs
2.  Install some sort of moisture/vapor barrier on/around CMUs
3.  Install rigid foam on both exterior and interior of CMUs


I haven’t been able to find any professionals around me that can provide any guidance.  I’m looking to see if anyone has any general suggestions on how to prevent moisture from causing this issue again.  Thanks in advance.  

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  1. Jon_R | | #1

    For the interior side of the CMU:

    1) a liquid applied vapor barrier
    2) well air sealed unfaced EPS foam to keep warm Winter interior moisture/air from reaching the CMU
    3) no Class I vapor barriers between the interior and #1

    Similar could be achieved with spray foam.

  2. user-7542295 | | #2

    Hi Jon -

    Thanks for you reply. Do you have any suggestions on products on you'd recommend? To provide some extra context, here are some pictures of the interior. One of my problems is there appears to be a potential gap/air cavity between the CMU and the framing/exterior as you can see in the attached pictures. Additionally, some of the electrical wiring is lay out in an less than desirable way. I showed a few GCs this and none of them made it seem like it was a major issue. Boy did I buy a doozy apparently.

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