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Hi everyone,

I'm creating this thread to document and get feedback on a foundation repair that I'm going to start on the home that I live in.

I purchased this home in February of 2020, knowing about the problem. Prior to putting the home under contract, I brought in an engineer to give his opinion of the wall and I felt comfortable with his advice and agreed that impending catastrophic failure wasn't an immediate concern.


A little of my background and objectives in this project - I am a licensed contractor - but masonry and foundations are not my niche by trade. Some of you may tell me to leave this to the pros but I wouldn't be where I am today if I haven't dug into something I knew little about. I do believe there is a line that has to be drawn on when to bring in professional help. The first steps in the process will be for investigation, and determine potential paths. I ask for your patience.

The home is a 2600 SF, "L" shape ranch, with a partially finished basement. I will draw a basement layout at some point showing the problem areas. From what I can see from inside, the two problem areas are along the front faces of the house. One CMU wall that is under our living room is the primary concern. The wall is approx. 27' long, and 2/3 of the wall bas a bow, with the largest deflection point being around 1-7/8". I found this by shooting a laser parallel to the wall and measuring at 3 points (sill, mid-point, and bottom of the wall).

From the top of footer to the sill is about 8'. There is a horizontal crack that runs at 4' elevation for the above mentioned 2/3's of the wall. There are also a few step cracks. Horizontal displacement is no greater than 1/8" at any point. Where the wall "T's" into the foundation for the "L" runout of the house, there have been previous repairs with what looks like parging. There's a shelf attached to the wall that I will removed for further investigation.

The second problem area is under our master bedroom. Same wall height and issue as described above but deflection no grater than 3/16" for the entire height of the wall. While this is minor, I plan to dig out the front of this section as well and repair it while I'm deep in this project. My plan is to also inspect the footer drain/french drain and repair/improve as necessary.

Engineers comment summary: he sees this frequently in the area we live in. Expansive soil was likely used as backfill and freeze/thaw cycles and hydrostatic pressure have caused the wall to push in. His recommendation was to excavate the exterior to remove the soil, he believes the wall will move a little back into place when the soil is removed, and then add carbon strapping to the interior, and backfill with rock.

The next steps for me:
1. expose more of the footer from the inside to see if the block has shifted from the top of footer, or first few courses.

2. Remove soil from front corner of the house to look at the brick ledge, foundation drain, and condition of the exterior foundation. I will start in a place where the wall hasn't moved in. This step is more for me to learn about the method of construction. From looking through my code book, I believe that the top course of block is a half width, which provides the brick ledge.

In the picture, you can see the 27' length of wall, and the repairs attempted by previous owner. The horizontal crack has what appears to be hydraulic cement, or parging applied to conceal. The step cracks have been caulked, and painting, as another attempt to conceal. I'm curious as to how the fillings in the cracks will effect the wall potentially moving back into plane.

Feedback appreciated. Wish me luck!
 

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If you have a concrete basement floor then you dont have to worry about the bottom coarse pushing away from the footer since the concrete floor holds the first coarse in place


Your walls have only deflected 1/8 inch?

How old is the house


Sent from my iPhone using Tapatalk
 

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Discussion Starter #3
The first wall is out almost 2”. Second wall is 1/8-3/16.

House is 25 years old.


Sent from my iPhone using Tapatalk
 

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Sounds like you're on the right track.
2nd the idea the bottom course not shifting with concrete floor. I would be curious about parging in corner. Covering serious settling? Footers may be broken. I would try to chip off and investigate.
Not huge fan of carbon fiber strips only for lack of knowledge. Relying on epoxy for strength. I prefer rebuilds with grouted cells. 2" out in 4 feet is alot to hope it comes back. Other wall not worried about. Relieve pressure, waterproof, new drains, no worries.
If funds allow, other walls will benefit by digging up and backfilling with stone to 1 foot below grade. Top with clay to slope away, then topsoil for grass/flowerbeds. Chances are they will fail eventually if pressure is not relieved.
 

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I think if your going to excavate lousy soil, mind as well replace a dozen blocks and grout anything you can. Drain able fill and clear footing drain will solve the rest.

PS don't smack the wall with the backhoe finishing lol. I've see that.
 

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So you are on the right track but if you are going to excavate make sure that you put a membrane and a dimple pannel on the outside wall . Stop any water from getting at it in the first place.maybe replace the weeping tile.
As far a carbon fiber it is the most effective thing to do but it must be installed at a maximum spacing of 4ft on center. If the top and bottom are anchored it adds approx 3 x holding strength.
It is correct that the failure can be the bond but is not the epoxy that fails its the concrete itself. So concrete block on average will fail at 250-300 psi pull test, so a typical carbon strap is 6in wide and if the crack is 4 ft up the wall that would leave 2sq ft of surface area above or below. this is 288sq in x 250psi = 72,000 psi bond break halfway up the wall. But if it was on the first course at the top or bottom it might debond that last course at 12,000 psi . So anchoring to the footer and rim joist is important. so you don't get any debonding. Re-tuckpointing the cracked mortar is fine.
 

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Sorry I did not explain . The anchor is made from kevlar and is epoxied on top of the carbon fiber strap. To connect the rim joist to the strap. The bottom of the strap is connected to a carbon fiber anchor to the bottom. The stress is distributed across the whole section. that is why you need every 4 feet. If you installed steel it would need to be also installed every 4ft but it works completely differently by trying to hold it back vs transfer the load.
 

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Sorry ... I don’t see how that oversize trailer tie-down strap is going to keep the wall from bowing.
As a mason contractor that prefers to rebuild the walls I am always skeptical about quick fixes as well however those straps are carbon fiber and are epoxied place

The Combination of epoxy and carbon fiber is ridiculously strong

I would consider them for a wall that has a slight push or bow in it to keep it from getting worse But me being the crazy person that I am by over engineering everything in my life I would also insist on injecting or pumping the cores of the blocks with grout as well


David
 

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As a mason contractor that prefers to rebuild the walls I am always skeptical about quick fixes as well however those straps are carbon fiber and are epoxied place

The Combination of epoxy and carbon fiber is ridiculously strong

I would consider them for a wall that has a slight push or bow in it to keep it from getting worse But me being the crazy person that I am by over engineering everything in my life I would also insist on injecting or pumping the cores of the blocks with grout as well


David
That block wall isn't grouted full with steel in every core?
 

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I see block walls with no rebar and no filling all the time. I've even seen that as a dry stack above grade.

You get cracks a long time before it's catastrophic.
 

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Different area I guess. Around here a block wall would have rebar in every core and a bar across every course and be filled. Unfilled wall wouldn't stand up to a 3.5 quake, and I slept through the last one of those.
Seismic zones is a whole different animal, most of the country doesn’t have to deal with that and rarely is a cinder block foundation wall filled solid.

That is why block foundation walls get such a bad reputation because they are not properly reinforced, it doesn’t help that the mason contractor probably didn’t use a good mortar to save a few bucks either


David
 

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Seismic zones is a whole different animal, most of the country doesn’t have to deal with that and rarely is a cinder block foundation wall filled solid.

That is why block foundation walls get such a bad reputation because they are not properly reinforced, it doesn’t help that the mason contractor probably didn’t use a good mortar to save a few bucks either


David
It seems like a poor practice to me. On a stem wall that's also a retaining wall, it's down right negligent.
I'm planning on evacuating California in a couple of years and moving to the south east. This is something I'll have to keep an eye out for when shopping for a home. Unfilled block foundation would be a deal breaker for me. Of all the places to cut cost, why on earth would you do it on the foundation?
 

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Most block foundations in the SE are not filled and definitely don’t have rebar unless there is a specific need. Certainly any older than 10 years is going to be that way. Exceptions would be within a city that has code requirements for it.
 

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Most block foundations in the SE are not filled and definitely don’t have rebar unless there is a specific need. Certainly any older than 10 years is going to be that way. Exceptions would be within a city that has code requirements for it.
Apparently I'm the only one here who's mind is totally blown by that. I see it as one step up from wood blocks. What else should I be looking for? I assume they frame with proper connectors and insulate the envelope?
I'm going to be so annoyed if I have to build my own house. I want to retire, not take on another project.
 
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