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Old 09-25-2012, 05:23 PM   #1
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CMU Foundation Spalling


I recently became concerned about some joint stepping on my CMU foundation wall just above and below grade, outside and in, at the back west side corner (one side only). I called in three reputable foundation companies and they advised me that I do not have a structural problem and simply tuck point the joints and parge the horizontal CMU spalling. The horizontal spalling is from two patio stones rubbing against the CMU over the years, and no one could identify any reason for the stepping.

After starting my prep work for tuckpoint and parging Iím wondering again about the corner CMU thatís sitting 2/3 below grade The deterioration seems more evident after removing the loose material, and it certainly seems like I could keep lightly chipping away at it. Iím worried that parging it with a parge mixture isnít going to help me if moisture starts getting in there again. Am I wrong? If water gets in between the block and parge ins't it possible moisture might wick up through the area further adding to the deterioration? Doesn't this happen anyway since the black bituminous parge coating isn't water proof and only damp proof?

Picture #1 shows stepping from inside (pic taken about a month ago). Pics 2 & 3 show outside wall as it was when foundation people stopped by (white powder is ant repellant). Pics 4 & 5 show the outside wall after some prep work for repair (taken today).












Note: the roof over hangs this area quite a bit and the land grade slopes away from the corner. I have witnessed a few heavy rainfalls since finding the problem and not a lot of water hits the corner, and thereís no evidence of any water penetrating the house at this location. The house was built in 1965 and I took procession 2 months ago. The home inspectors also said the stepping wasnít a problem. Inside pic shows previous patch job.

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Old 09-26-2012, 01:14 AM   #2
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CMU Foundation Spalling


Recommendation:

Pressure wash area clean as possible.
Paint with concrete bonding agent.
Parge with type S masonry cement
Paint with concrete waterproofing agent. (3 coats)

This should keep the problem from re-occurring. It looks like water was sitting there, absorbing into the block, freezing and cause the spall? Just a theory.

As far as the stress fracture in the mortar joints... Yes the foundation has settled. They all do. But.... you say no water is getting over there but it looks like it is. 2 sure signs of water damage, cracked joints and spalling. Might want to double check eh? You would think the brick would show some sort of sign as well, right? Usually when the foundation sinks you see it in the brick as well. Maybe not if wall ties were used but you said the house was built in the 60s? Tricky one here...

GL


Last edited by TRUEPRO; 09-26-2012 at 01:16 AM.
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Old 09-26-2012, 03:35 AM   #3
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CMU Foundation Spalling


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Originally Posted by TRUEPRO View Post

As far as the stress fracture in the mortar joints... Yes the foundation has settled. They all do.
I wouldn't be so sure those cracks suggest settlement. They don't seem to go up into the brickwork, which they would if the cormer was going down.
It's the classic case of the different properties of clay brickwork and CMUs when used together.

Over time, clay brickwork expands slightly as the initially kiln-dry bricks take up moisture from the air. Conversely, CMUs shrink after construction, often giving the familiar stepped cracks. (Although stepped, your cracks seem to run in and out down aternate courses, which suggests expected shrinkage. The time to worry would be if they ran down diagonally at 45 deg.).
My guess is that the cracks have been there a long time and don't suggest anything serious, just water penetation.
Keep it simple and just do what the foundation people have suggested.
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Old 09-26-2012, 12:45 PM   #4
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CMU Foundation Spalling


Quote:
Originally Posted by TRUEPRO View Post
Recommendation:

Pressure wash area clean as possible.
Paint with concrete bonding agent.
Parge with type S masonry cement
Paint with concrete waterproofing agent. (3 coats)

This should keep the problem from re-occurring. It looks like water was sitting there, absorbing into the block, freezing and cause the spall? Just a theory.
GL
Thanks for the recommendation.

Quote:
Originally Posted by TRUEPRO View Post
As far as the stress fracture in the mortar joints... Yes the foundation has settled. They all do. But.... you say no water is getting over there but it looks like it is. 2 sure signs of water damage, cracked joints and spalling. Might want to double check eh?
GL
I was kinda predicting snow and ice between the patio stones and block, possibly some frost heave against the block from the patio stones (i'm in southern ontario, canada). Really though, I’m not sure what I was thinking …. I’ve only been in the house 2 months and while it appears like not a lot of rain hits the corner it’s way too early for me to draw any conclusions about the water. I need to monitor it more. I also suspect it helped a lot when the eavestroughs were replaced last year plus gutter guards were installed. I added gutter spout extensions when we moved in and rain barrels with spout extensions are next.

Quote:
Originally Posted by TRUEPRO View Post
You would think the brick would show some sort of sign as well, right? Usually when the foundation sinks you see it in the brick as well. Maybe not if wall ties were used but you said the house was built in the 60s? Tricky one here...
GL
Built in 1965. There’s an old washroom vent hole through the brick vaneer that wasn’t sealed properly and when I clean it up maybe I can get a peak between the brick and sheathing to confirm wall ties. I’ve been curious about that. I purchased a neat DeWalt 3ft x 17mm inspection camera that has been extremely handy over the last two months, like finding one of my air ducts stuffed with tennis balls lol. When did wall ties become standard practice?

Thanks!

Last edited by lilbilly; 09-26-2012 at 01:22 PM. Reason: clarification
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Old 09-26-2012, 12:47 PM   #5
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CMU Foundation Spalling


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Originally Posted by tony.g View Post
I wouldn't be so sure those cracks suggest settlement. They don't seem to go up into the brickwork, which they would if the cormer was going down.
Although all three companies couldnít confirm what itís from they all said it wasnít settlement.

Quote:
Originally Posted by tony.g View Post
Keep it simple and just do what the foundation people have suggested.
Sounds like a good plan. Thanks for the advise.
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