Block Basement Wall Bed Joint Crack

BreyerConstruct

Ok, here's the info:

I looked at a property last week for a pretty long list of issues.
One that I'm not sure about is a horizontal crack in the front wall of the foundation. The house is an approx. 24' x 40' rancher, with a full block basement. I don't know the date, but I'd guess it's about 40 years old.

The front wall of the basement has cracked 1/2 way up, and followed the bed joint.
The rest of the wall looks good.
The wall has bowed in slightly. I didn't get an exact measurement, but I'd peg it at maybe 1/4" in from plumb.

The first thing I did was check the site & grade. Everything around the front looks good, but the landscape is newer, and may be masking an old problem.
The front gutter looks like it's overflowed, but I couldn't confirm if it's failing currently, or just has in the past.

I've followed an engineer's report before for a basement where we used a Thoroseal (SP?) product to clean a joint, then patched and painted everything to spec.

I'm not one to "wing it", and I'm glad to get my archatect or a refered engineer in to look at it. However, I'd loveto hear you guy's thoughts, so I can better weigh what I'm told, and perhaps better know which questions to ask.

The crack appears to be old, and dosn't appear to be currently moving... but I don't trust big cracks in foundations, even if it's block.

Any thoughts would be much appreciated!
Thanks,
~Matt

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cleveman

The wall is only 1/4" in?

And you're worried about this?

Good of you to check out the grade.

My first inclination is not to worry. If you must fix it, then pull the wall out slowly with anchors, then you can point the bed joint.

Tscarborough

I am not familiar with basements at all, but assuming that a CMU basement wall is nothing but a CMU retaining wall with a high compressive load, my assumption would be as follows:

A horizontal crack in the bed joint is indicative of hydraulic pressure. The location of the crack and the fact that there is no zig-zagging indicate an evenly applied stress that eventually causes a bulge. 1/4" is well within the parameters for a CMU wall to open a crack, esp. if the wall is unreinforced (or is over the design load) vertically with grouted cells and horizontally with reinforcing wire.

As with any structural defect, the problem should be solved before a repair is attempted.

If it were me, I would move on or request that it be repaired prior.

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concretemasonry

You are describing a classic wall failure, except the crack is usually one course above the midpoint of the height. This is a failure because it cracked and moved, even if water did not come in.

The vertical load on a basement wall is very low. That horizontal load is what dictates the thickness and reinforcement. Without any soil load, a basement wall could be 6" block or less.

All it takes is an excessive horizontal force at any time from the soil or even during improper backfilling to create the initial crack. The age of the crack is not of major importance since the soil conditions could occur again.

Because the wall has cracked, it is MUCH WEAKER than it was when built. It will NEVER be as strong as new. It is standing and performing adequately now, but you never know about the future conditions and soil loads.

What you described before was really cosmetic repair and the engineer was responsible if you did the work as required. Thoroseal is a wonderful product and its only drawback is that it can make thing look too good and give a false sense of confidence sine it just a great waterproofer/repair material.

Do not make any recommendations orguarantees about the future. Hire a professional that has registration and insurance to make the recommendation, so it is his problem if there is future damage or very costly repairs/replacement.

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Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

BreyerConstruct

Dick,

I thought this topic might pull you in.

Guys, thanks again for the input. What I'll be doing is creating an estimate th address the rest of the renovations needed, and will explain that for this section something does need to be done, but that we need to get an engineer on board 1st to create a proper solution. If they're serious about improving the property, and I do a good job of clearly communicating the need, it should work well.

Thanks again for sharing your thoughts & knowledge, this site is invaluable in helping me/us all grow better in our businesses!!

~Matt

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