wall cracks, structural engineers and crawl spaces


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Old 09-24-18, 06:52 PM
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wall cracks, structural engineers and crawl spaces

Back in 2014, because of two main cracks in the drywall (one above the entryway to the front room and one in the kitchen), along with two hairline cracks in the cinder blocks in the crawl space, we hired a structural engineer to do an assessment.

Their summary stated:

"Based on my observations (the cracks are relatively small, there was no apparent movement of the house framing and no significant corresponding cracking of interior walls), the foundation cracks are most likely settling/soil movement type cracks for your area. Your area (the Triangle area of NC - we're in Durham) is knowno for its expansive clay soils, These soil conditions tend to create more foundation cracks than more stable soils. The interior dry wall cracks are also caused by the soil movement. The cracks should be monitored for movement. Not structural repairs are required at this time as a result of the cracks. A re-evaluation will be necessary if the condition of the cracks changes. "

We had our house painted April last year and the cracks have not only reappeared, but in addition to be flush with the call and just running along the wall, they kind of bulged out maybe 1/4" (like the wall somehow shifted a little horizontally).

We are in the process of getting quotes to have our crawl space sealed, but my wife thinks we need to have another structural engineer come out before they do that (which I'm opposed to, give one the one engineer said above - that's it's the soil. We have a lot of clay around and I think we'd be pissing money away having jacks or piers installed.

Would sealing the crawl space and creating a closed environment keep the house from settling so much (since the clay wouldn't be influenced so much by the hot and cold environment it currently goes through each year?

I know the cost to correctly do a closed crawl space is anywhere from $7000 - $10,000. I'm ok spending that kind of money if it solves the other issue. We're are looking at doing this to get rid of a musty smell in the living room area (and there are signs of mold on some of the woo\d in the crawl space). I'm hoping a side effect of doing this (the closed crawl space) will be to stop the settling of the house. Just looking for advice/opinions on this.

Thanks,

Andy
 
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Old 09-24-18, 06:56 PM
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These are the type cracks I'm referring to:

MISC by hikerguy1 | Photobucket

We also have issues with the lower cabinets pulling away from the wall by aout 1/2" during certain parts of the year (then it goes right back in place other times).
 
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Old 09-24-18, 08:41 PM
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The problem in your case, according to your inspection, is that your footing rests on expansive soil (clay). Footings are supposed to provide a solid, stable base for the home... (on most soil types that are stable) but when that type of soil gets wet, it expands and heaves the foundation which moves the house. It's similar to hydraulic pressure. Very hard to resist those kinds of forces.

This is hard to predict, (at the building stage) hard to control, (lots of rebar reinforcement in the concrete) almost impossible to eliminate. (Repair after the fact). The water source could be limited if it is something you can control (clean gutters, longer downspouts, etc.) But since we are talking about the earth under the footing it is deep and so could be the result of ground water. (Not something you can control).

I don't know that there is any "solution"... it is what it is. As he said, all you can do is monitor the problem and watch if it gets worse. If you never fix the drywall it will obviously look worse every year. But it doesn't mean the structure is getting worse. Drywall is easy to repair, so you can make cosmetic repairs as needed. But you will likely have to do it over and over since it is going to be a recurring problem.
 
 

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