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Has anyone used Xcluder Cinder Block Caps?

jenniferz5 | Posted in General Questions on

Now that the weather is cooler, I have turned my attention to my mouse problem.  One product that I discovered was the Xcluder Cinder Block Cap (  My plan was to insert fiberglass batts just into the holes (as Martin has recommended), then cover tightly with aluminum cloth held in place with caulk.  The Xcluder Block Cap product seems even easier, but do you see any issues?  

We live in Zone 5a, CT; our crawlspace is covered in plastic; the rim joists are filled with insulation; the exterior foundation has been treated with a bituminous layer and Rockwool ComfortBoard IS.

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  1. user-2310254 | | #1


    I'm assuming you want to seal your foundation walls, correct? Is there room to fit the cap under the mud sill? Also, I didn't see where you could buy this product. Do you find a source?

  2. Expert Member
    BILL WICHERS | | #2

    It might be challenging to install these into an existing block foundation wall. It looks like there is a formed depression in the metal plate that is intended to fit into the hole in the block. Depending on how deep that depression is (the data sheet doesn't seem to say), it might be impossible to slide these into place on an existing wall. With a new wall, or a wall where most of the top of the block is accessible, I don't see a problem using these. I would probably skip the adhesive step though with an existing wall and just rely on pressure from the sill plate to keep things in place, but you'd have to check that with your particular wall to see if it was secure enough.

    If you're going to be jacking up an existing home a little to try to slide these into place and find they don't fit, you could get some galvanized steel sheet and form a lip on one edge to have a barrier than can slide in (no formed recess this way). Any sheet metal shop should be able to make these for you pretty easily. Just get pieces four feet wide, have the distance from the bend to the edge made the same as the depth of your wall, then have a lip of 1/4 to 1/2" or so formed on one edge (this is just a 90* bend). To install these, just jack up the sill plate to allow about a 1/8" or so gap between the bottom of the sill plate and the top of the block wall, then slide the sheets into place until the lip is flat against the wall. The lip gives you a stop so that you can easily tell when you have the sheets installed all the way.

    I do this with HDPE sheets to add capillary breaks, but mice can chew through those if they're determined enough. Galvanized steel will be chew-proof. Note that you'll be introducing a thermal bridge that could get some minor condensation issues, which would also happen with the Xcluder cap. While likely not much of an issue in practice, you could glue on some rigid foam insulation to stop the condensation. Even 1/2" would be enough to avoid most issues, but more is better.


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