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Discussion Starter · #1 ·
When I bought my house 2.5 years ago the inspector saw the vertical crack almost on the middle of the foundation on the back of my house. He said it looked like normal set telling and did not act concerned about it. Well, the other day an inspector came out to inspect so e footings for a deck I'm building and he pointed out the same crack. He told me to dig to the footing around the crack and check it out. I haven't done that yet but I did go under the house where the crack is and the blocks are cracked in half all the way through. I called a contractor and he said it was a very common problem in the area and was a pretty simple fix. No blocks need to be replaced but patched up. That's one good thing. What would you guys do in this situation? I have the recommendation from the contractor but I want to see what you guys say bfirst to see if it matches up.
 

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If the crack is more-or-less vertical and the same width top-to-bottom, it could just be normal initial shrinkage of the blocks. CMUs are known for this, particularly on long straight runs.
 

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Discussion Starter · #8 ·
It's close to half way and the foundation wall there is about 5' tall. I have not dig down to the footing yet but I do know the foundation is stepped right beside the crack. Not sure what that means but that's what the inspector said.

Sorry. Misread. Wall is roughly 40' long.
 

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If that the new ledger for your new deck, did the inspector say anything about the bolts all being in a row like that?:eek:
That can cause the board to split along it's length ot cause it to cup.
 

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Discussion Starter · #10 ·
joecaption said:
If that the new ledger for your new deck, did the inspector say anything about the bolts all being in a row like that?:eek:
That can cause the board to split along it's length ot cause it to cup.
The bolts are in a W shape so there are just as many on top about 4" apart from bottom bolt to top bolt.
 

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Concrete block walls are subject to drying shrinkage soon after construction, and because of that suitable movement joints are usually built into the wall. These can sometimes be seen as vertical lines about 1/2" wide, and filled with a flexible sealer.

The joints are recommended to be at 20 - 30 ft intervals depending on the actual type of block, and moisture content when they were laid. At 40ft long and without any movement joint, I would be surprised if your wall hadn't cracked through drying shrinkage.

This is not to say that it isn't a foundation settlement problem, but pesonally I would think that unlikely owing to the position of the crack, and the fact that it is fairly even in width top-to-bottom.
 

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Discussion Starter · #12 ·
Sounds good to me. What would you recommend to fix it or just prevent further spreading? It's looked the same from outside for the 2.5 years I have been here so no obvious movement has occurred.
 

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Concrete block walls are subject to drying shrinkage soon after construction, and because of that suitable movement joints are usually built into the wall. These can sometimes be seen as vertical lines about 1/2" wide, and filled with a flexible sealer.

The joints are recommended to be at 20 - 30 ft intervals depending on the actual type of block, and moisture content when they were laid. At 40ft long and without any movement joint, I would be surprised if your wall hadn't cracked through drying shrinkage.

This is not to say that it isn't a foundation settlement problem, but pesonally I would think that unlikely owing to the position of the crack, and the fact that it is fairly even in width top-to-bottom.
You won't find control joints in 99% of residential construction here in the US. Plus, shrinkage cracks rarely transfer through the shells of the block themselves, and almost always follow the joints as "step cracks". Generally, the only time they shear the block themselves is if there's an excessive amount of deflection at that point of the wall, or if the mortar is stronger than the block itself.

Nikeman, it would be best if you could get a dry line mounted near the top of the wall and check to see if the wall is still straight or if it's slightly bowed.......
 

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Discussion Starter · #14 ·
Here's what contractor said


Dig 2 2' deep holes under house and fill them with concrete. Then jack up house at that area about 1/4" and make concrete columns on top of concrete. Then support at least 3 joists with 3 2x8s bolted together on top of block columns. I know the upstairs bathroom which is right above where the crack is has a slightly unlevel floor and the window frame is narrower on top then the bottom. It's only noticeable when hanging blinds which is how I discovered it.
 

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Jomama; those pics don't suggest uneven foundation settlement because the crack looks fairly even in width.

All concrete block walls undergo shrinkage though, as you imply, with softer mortars it will not be immediately apparent. The shrinkage will still be there, but it will be more evenly distributed by several hairline cracks, rather than one wide one. It's also worse if the blocks were too wet when layed.

OP doesn't say how old the house is, but that the crack has been like that at least 2 1/2 years. My guess is that it happened soon after the house was built. If the contractor says its a common problem around there, then maybe its the local type of block; surely all the houses round there won't have identical foundation movement?

It's an aesthetic/weatherproof problem and the crack just needs filling. A crack like that won't make the bathroom floor uneven - that's probably just a coincidence.
http://www.aggregate.com/Documents/TDS/Masterblock-Concrete-Block-Technical-Manual.pdf page 31.
 

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Discussion Starter · #16 ·
House was built in 1999. Contractor says the soil in the area causes these cracks and he sees them all the time. Crack was there when I bought the house 2.5 years ago but recently its been pointed out to me on several occasions. He recommended using concrete in a tube or something to patch up the crack. Ill do as he suggested with the 3 2x8s on block columns on top of 2' concrete footings. Then patch the crack and be done with it. Ill probably go around the foundation under the house and look for more cracks also.
 

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Discussion Starter · #18 · (Edited)
He said they use some cheap kind of dirt to replace the dirt that was there before excavating when building begins instead of back filling with original dirt. Not sure why this would be done but its the same dirt all around the house.


Edit: thinking about it now. I don't know if it was the contractor who told me that or not. Maybe the builder said that. The contractor did day it was very common and not a major issue which is good to know.
 

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Never heard of that one!
Can't see what difference backfilling with 'cheap' dirt makes.
What's the structural difference between cheap dirt and premium dirt?!
It's normal shrinkage cracking - nothing more.
 

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Discussion Starter · #20 ·
tony.g said:
Never heard of that one!
Can't see what difference backfilling with 'cheap' dirt makes.
What's the structural difference between cheap dirt and premium dirt?!
It's normal shrinkage cracking - nothing more.
That's good. Would you guys just patch the crack and let it be or do as recommended and dig the 2 footings and 2 concrete columns?
 
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