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Community and Q&A

Protecting Rim Board from Wet Concrete

bongo30 | Posted in General Questions on

Hello, what is the best way to protect Rim Board from wet concrete. This is for new build, concrete was recently poured. Is Ice & Water shield self adhesive membrane sufficient? Or shall we use rigid foam? I’m attaching the proposed solution for criticism/suggestions. Climate Zone 4. Thank you.

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  1. Expert Member


    Yes, a self-adhered membrane is what you want. You can apply the membrane to the back of the rim-board. If there is no sill-seal under the ACQ sill-plate you should also run a piece of membrane over it to stop moisture migrating upwards.

  2. Deleted | | #2


  3. bongo30 | | #3

    Thank you! Just to clarify, would you run it under or over the ACQ?

    1. Expert Member
      MALCOLM TAYLOR | | #4


      It doesn't make much difference. The ACQ sill is already protected. The membrane is there to stop moisture making it's way up to the rim-board and bottom flange of the I-joists.

  4. bongo30 | | #5

    Thank you again!

  5. Expert Member
    BILL WICHERS | | #6

    You would do well putting them membrane in as a capillary break even with a pressure treated sill. The less that sill gets wet, the longer it will last, even though it's treated. Treated wood lasts longer, but not forever, so a little extra insurance with a capillary break is a good thing, and it's FAR easier to put it in now than to try to add it in later.


  6. Expert Member
    Akos | | #7

    One option could be to simplify the design and use a wider sill plate and hang the I-joists off top-flange joist hangers. This saves a rim board plus forming the ledge in the foundation. The joist hangers add a bit of extra cost, extra labor is not too bad as these use only a few nails each.

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