I have an 11 course masonry block basement foundation wall with a horizontal crack and it's bowing inward by 3/4". An engineer that I used to work for would suggest fixing any bow in a residential basement wall equal to or over 1/2" over its full height but I'm looking for where in the code books it discusses this. I've read online from multiple sources that the TMS 402 has a limit of 0.007h but I downloaded this text and can't seem to find this information anywhere in the book. Can anyone shed some light on this topic? 0.007h sounds correct but I can't seem to find it laid out in those figures in any of my code books.
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Acceptable Inward Bow in Basement Wall 5
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- #21
OldDawgNewTricks
Structural
Buyer beware for the digital version. Ever since TMS took over from MJSC, they won't sell you a regular pdf. It's only available in a LockLizard version that can only be viewed on one computer with their viewer and has limited printing capability with watermarks. I think I will be switching back to hardcopy for the next edition.
I've come across this situation numerous times. (sans the attorney though...)
What Greenalleycat wrote is pretty much what I'd say.
One other thing though, I don't subscribe to the "hydrostatic pressure" line of thinking (too much).
The wall does not have the strength to safely resist horizontal loading. USUALLY (around Southwest Ohio) the culprit is moisture sensitive clayey soils. When they get wet, they swell and push the wall inward. Once the wall moves out of the way, the pressure deminishes. When they get dry, the clayey soils shrink. If the pressure from a column of water was there, the wall would keep moving in.
That's just how I look at it. You're welcome to disagree. I have avoided these types of assignments over the past several years. I've been lucky to be busy enough without this type of headache job.
As far as when to recommend structural repairs - I always tell my clients that whoever owns the house, owns the problem that could progress to an unsafe condition at any time (as GAC wrote). Generally I say that ANY movement is cause for concern about the durability of a wall and 1" is the most common threshold of movement whereby a structural repair is typically recommended. I am not aware of any code (building or design) that prescribes a limit. Basically, if it's broke (ANY crack and inward movement), it can't support the code required load.
What Greenalleycat wrote is pretty much what I'd say.
One other thing though, I don't subscribe to the "hydrostatic pressure" line of thinking (too much).
The wall does not have the strength to safely resist horizontal loading. USUALLY (around Southwest Ohio) the culprit is moisture sensitive clayey soils. When they get wet, they swell and push the wall inward. Once the wall moves out of the way, the pressure deminishes. When they get dry, the clayey soils shrink. If the pressure from a column of water was there, the wall would keep moving in.
That's just how I look at it. You're welcome to disagree. I have avoided these types of assignments over the past several years. I've been lucky to be busy enough without this type of headache job.
As far as when to recommend structural repairs - I always tell my clients that whoever owns the house, owns the problem that could progress to an unsafe condition at any time (as GAC wrote). Generally I say that ANY movement is cause for concern about the durability of a wall and 1" is the most common threshold of movement whereby a structural repair is typically recommended. I am not aware of any code (building or design) that prescribes a limit. Basically, if it's broke (ANY crack and inward movement), it can't support the code required load.
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- #23
StrucPatholgst
Structural
All good points, except the carbon strap thing. In my area the carbon strap guys have language in their warranties that void coverage if the block ever gets wet. That's a hard no for me.
Also my quick rules of thumb are:
1. If it's cracked, it technically failed at its job but still may be stable. Regardless, something needs to be done.
2. If the CG of the wall has moved into the outer third of the thickness of the wall, then stability and moment effects start to become a big problem, and repairs or replacement should happen as soon as practical.
3. If it's a long crack at or near grade on one wall, 90% of the time it's freeze-thaw action.
Also my quick rules of thumb are:
1. If it's cracked, it technically failed at its job but still may be stable. Regardless, something needs to be done.
2. If the CG of the wall has moved into the outer third of the thickness of the wall, then stability and moment effects start to become a big problem, and repairs or replacement should happen as soon as practical.
3. If it's a long crack at or near grade on one wall, 90% of the time it's freeze-thaw action.
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- #24
Just about every masonry basement in my area has a crack due to the plastic clay soils. I usually tell folks to visually monitor the cracks for further movement. Usually, 1 1/2" of bow is about my limit before I tell them to fix it. I have yet to see one collapse.
I have probably looked at over 1,000 of them over 30 years. Carbon fiber or soldier beams are generally what I specify. Have not seen the warranty thing about the CF strips though. Thanks for the heads up.
I have seen them install the CF strips over paint! They were peeling off easily.
I have probably looked at over 1,000 of them over 30 years. Carbon fiber or soldier beams are generally what I specify. Have not seen the warranty thing about the CF strips though. Thanks for the heads up.
I have seen them install the CF strips over paint! They were peeling off easily.
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- #25
Regarding CF strips:
I've never heard of the wet condition issue but I HAVE heard that FIREPROOFING IS NEEDED for CF to qualify by the CF design rules.
Improved anchorage at top and bottom is also a detail issue with any CF or pilaster type improvement. That force has to go somewhere!
I've never heard of the wet condition issue but I HAVE heard that FIREPROOFING IS NEEDED for CF to qualify by the CF design rules.
Improved anchorage at top and bottom is also a detail issue with any CF or pilaster type improvement. That force has to go somewhere!
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