Cracked Off Skim Coat Over Block Foundation

Old 03-10-23, 03:50 PM
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Exclamation Cracked Off Skim Coat Over Block Foundation

Broken & cracked skim coating over concrete block foundation, as seen in the picture. We Don't get any leak or anything at this point, at this time, there is a full footprint basement with this foundation, however, how concerned should I be about this? This side of the house the skim coat is all slowly cracking and/or coming off, other sides the coat is fully intact. This is a 70 year old home. There is no roof overhang here, this is almost just beneath the gable at the front of the house. The skim coat is only breaking away along this section from corner to corner, but above the entire section there is no fascia or overhang, as opposed to the rest of the house.
I appreciate any informed response. Thanks so much.

see the concrete skim coat has broken off of the block wall
Old 03-10-23, 04:06 PM
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The parged coating is just for looks. It likely does not extend far below grade, you could dig a little to know how deep it extends. The bad bond is an easy path for water to follow but I doubt it is affecting the interior much if at all. Wherever that coating ends below grade is as far as trapped water (between block and coating) would go... after that it's into the soil.

Looks like the outer layer of block is eroding along with it, that can be from frost and freeze thaw cycles. No easy fix other than chiselling it all off, brushing on a bonding coat, and parging it again. Many products nowadays (such as Shurwall) would likely require fiberglass mesh embedded between multiple coats to strengthen the coating. Your coating is likely just a one coat, non reinforced Portland mix, and the bond has failed.

Aside from frost action, you also get splashing and wicking of water that can get behind it since the top edge is not sealed under your siding.

If you don't have gutters, or if you do and they are plugged, you get a lot of runoff and splashing from water coming off the roof that would hasten its failure.

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