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ax525 12-27-2007 01:41 PM

Corner Cracks
1 Attachment(s)
As many more houses in South Texas, our house suffers from exterior corner cracks in the concrete slab. All corners with cracks were covered with concrete when we first moved in three years ago. About one year ago, one of the corners separated from the house (see link), but no other problems have been seen (no cracks in the interior corner, walls, window or door frames, etc). I'm concerned because the "crack" went beyond the slab and reached the masonry. Any tips in how to repair this problem? (I tried before, but the result is obvious). Is it time to call a contractor?

Any comments will be appreciated.

- Frank

glennjanie 12-28-2007 11:07 AM

Welcome Ax:
Concrete and masonry are subject to cracking; this one is very small and is of no consequence. I would'nt worry about it.

STG 06-15-2008 06:46 AM

I'd like to bump this topic and get some more feedback.
I conducted a repair on my house this weekend for this very same issue. I chiseled out the crack a bit with my cold chisel - but didn't go all the way into it. The crack was quite small - but there was an area a bit deeper that had a 1/8" crack in it that I did not go deep enough to completely access. I was concerned about breaking the concrete corner completely off the foundation.

The crack is diagonal on both sides of the corner of my house. It starts about 10" from the corner and works its way to the corner edge on both sides. When I chipped off the cement overcoating, I found that the crack was very narrow - the cement was actually touching below the surface with no visible gaps...with the exception of the area with the 1/8" gap.

The larger area was at the very top of the crack on the side of the house that gets the most sun. I'd opened up the top of that crack area a bit (about a 1.5" wide x 1" deep section). The larger crack was visible from this area.

Once I'd verified that, with the exception of that larger cracked area, the cracks were present, but the concrete was touching, I attempted my repair.

First, I mixed up Quikrete vinyl concrete patching compound. According to Quikrete's website, this stuff has a compressive strength of 3000psi at seven days and 5000psi at 28 days. I packed it into the area I'd opened up at the top (and from where the larger crack was visible) to the point of refusal. That is, I couldn't stuff any more of the crack repair in. Whether it made it to the larger crack is unknown.

I then covered the rest of the crack with the the patching compound. The crack was covered in an area about 2" wide and 1/4" in depth.

For what it's worth, My house is a 1600 square foot, single-story home on a slab foundation. Three sides of the house are brick - the back of the house is siding. The foundation is coated in a stucco-like concrete parch coat. The house is located in north-central San Antonio where the soils are a combination of clay and limestone. The limestone bedrock is about 10 inches below the ground surface.

There is no interior damage to the wall or ceiling sheetrock, all the doors and windows function fine. The cracks in the corner appear to be limited only to the outside - I pulled up the carpet and found no cracking on the interior slab in that area.

Was this a decent repair?

Should I be freaking out about this type of wedge crack?

STG 06-15-2008 08:14 AM

I've uploaded photos of the repair.

The first two pictures are of my house after repairing the crack in the manner I described earlier.

Other side:

The third photo is of a home near mine that has not had any repair done. This crack is in the far left hand side - mine did not look as bad as this prior to the repair. There is also some breakage on the top where the concrete meets the brick facing. My house also had that issue.

glennjanie 06-15-2008 12:46 PM

Welcome STG:
Your corner repair is a beautiful piece of work. I'm sorry I put Frank off about his corner; I think he could use your method on his home too.
The parts that are cracking and popping off have one thing in common, there doesn't seem to be any agregate (rocks) in the concrete. This is the result of attempting to drag the concrete around too much in the forms or the truck gets empty and the pour is continued an hour or so later (cold joint). The patching material and methods appear to be working well and I would recommend both to homeowners having the same problem.

STG 06-15-2008 01:06 PM

Thanks for the welcome and the feedback.

This happens on many houses here, Glenn. What people "in the business" have told me is that this results from the brick pushing against the corner of the foundation. It actually pushes the corner out of the slab. I have a few broken bricks, too...but I think that should be OK. They're level and they have not separated.

The repair I did sound like a sensible thing?

I've been a little concerned about the 1/8" crack I saw inside the area I chipped out - it almost seems like there was a void in there. I'm just hoping the Quikrete I put in filled it to some degree.

Frank, if you're in south Texas, feel free to email me and I'll talk you through what I did.

STG 06-15-2008 04:47 PM

Wonder of wonders...

I just talked to my neighbor who's been doing a bunch of work on his house this weekend, too. Turns out that he's a retired concrete contractor.

He says that there's little one can do other than cover up this sort of thing. It's a cosmetic issue and can't really be repaired - just bandaged. We're going to attack this next weekend and make some repairs to other hairline cracks as well as this one in both of our foundations.


How ironic to learn that only after making the repair.

kflack 10-09-2008 09:22 AM

I have a similar problem. House built in 2004....

Here are a few pictures of the problem.

Just called the contractor but not sure what needs to be done.

Note; Resent activities in the area
1) Road Paving last year 25 ft away (Steamroller Vibrator shook whole house)
2) New house being built next door (Alot of concrete trucks stopped with 10 ft of the broken corner.
3) 3 years ago a large drainage ditch installed within 10 ft of corner house.
4) Drain pipe drains within 2 ft of corner.

What would your recommendations be.....

Note: Evening temperature just started to drop below 0 deg (freezing)

glennjanie 10-10-2008 09:03 AM

Welcome Kflack:
The cracking problem is not a weight problem, nor are any of the other things the reason. In my opinion the problem is in expansion and/or poor placement of re-bar in the concrete (re-bar controls expansion, so its all the same).
The corners could be chipped off enough to expose the re-bars fully and rebuild it with the above mentioned 'hi-strength' premixed concrete. However, it is really just a cosmetic thing and any patch will be simply cosmetic also. The houses will probably stand for many years without any help but some color matched caulk would help to hide the problem.

mzullig1 10-12-2011 01:50 PM

Similar Problem with cracked foundation at corner
4 Attachment(s)
I'm guessing that my issue with cracked foundation at corner of my house is of no issue as well. Can someone give me their assessment if this is an issue? Below are pics of the cracked corner at foundation slab.



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