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Moisture Barrier for Partially Below Grade Grouted CMU Wall

4077 Views 4 Replies 2 Participants Last post by  Fire4Effect


We gutted our kitchen as part of a repair to our foundation. While removing the drywall from the wall separating the kitchen from the garage we discovered the sole plate for the wall rested 24” above the floor and the drywall was not fastened to the grouted CMU wall. We asked the contractor who rebuilt our floor to use a moisture barrier between the plywood and the grouted CMU wall and he left us the rest of the roll. The moisture barrier is the black sheet material rising from the floor in the photo above.

The soil under the garage slab starts about 12” below the sole plate. We thought we would add another section of the moisture barrier from the sole plate down to the floor. Does the moisture barrier need to overlap the layer of moisture barrier below and by how much? Next we would fur out the wall with 1x4. Do the furring strips need to be pressure treated? Finally we would cover with 5/8” moisture resistant, fire code drywall.

Is this the best code compliant approach under the 2006 International Building Code?

Thank you for taking the time to read my post and consider my questions.

Howard
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you should not be using a moisture barrier (looks like felt paper) on the wall at all. This will stop water transfer and water from the outside traveling inward will collect in the wall. Best way to fix this is to build the wall with an airspace to allow the exterior wall to dry when and as needed. Pressure treated wood is only needed if wood is in direct contact with the CMU.
Hi Bob,

Thank you for responding. Without a moisture barrier the furring strips will be in direct contact with the CMU wall. Sounds like I need to run pressure treated furring strips from floor to ceiling.

Howard
use foundation sill insulation behind them. This will also act as a buffer for any irregularities in the block wall as well as a capillary break to stop water.
use foundation sill insulation behind them. This will also act as a buffer for any irregularities in the block wall as well as a capillary break to stop water.
Bob,

I did a search and I can't figure out what foundation sill insulation is.

Howard
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