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Cmu exterior wall with cracks

Hello all, We are emailing from Charleston, SC literally right on the marsh. Its in a flood plain but the view is amazing...at least until you start looking at the CMU Exterior wall on the two rear corners of the house. The inspectors report stated we should have the cracks that string along grout lines looked at. First contractor said to fix our problems with drainage and we would see our problems go away...so we installed gutters to reroute water away from the house, as well as graded the dirt to slope away from the house. Now, here in lies the problem...how do I know if the sinking has stopped or if that was my problem in the first place? Do I need to install heilical piers as others have suggested. Or leave it be? There will also be piers installed inside the crawlspace where they are badly needed. Is this a case where I should wait and see if the cracks expand more...or a case where I need to act now to remedy the situation. Thanks!

Re: Cmu exterior wall with cracks

In your area if your home was built in the last 20 years it would be on pilings and from mean High tide to the 12 Ft. elevation would not be consider as a living space.
The CMU between the pilings would be blow-out panels and attached to the pilings with pins or other attachments 4 each side.
You should contact a structural engineer and have him evaluate the materials used.

Re: Cmu exterior wall with cracks

Mrswhitsie- We live in the Lowcountry as well and I am curious if your home was built on piles. If you're having helical piers recommended by multiple 'others' it sounds as if that is not the case.

It seems like you're on your way to figuring out the best way to move forward, but if I was you I'd get as many qualified people as I could to give me an cost-free assessment. In some circumstances you can get 5 diff't opinions from 5 people. However, w/ this issue I'd suspect that the majority will be in agreement and likely be helping you know what to do and how to do it if you listen carefully and consider everything you're being told.

Watching and waiting if it gets worse seems like an option, but if an engineer with experience in this area is not recommending this I think you need to make plans to shore up things better structurally sooner than later.

Re: Cmu exterior wall with cracks

You should have moved up to the upstate where we trade your big infrequent Hurricanes for our smaller frequent Tornadoes!

As to the cracks, I'd have a mason come out and "point" them back. This involves chipping out enough mortar to put new in it's place. If the wall is not moving anymore this is permanent. However you're on sandy soil so I'd bet you're dealing with an unstable foundation. In that case you're not going to find an easy permanent fix. The only permanent cure I know of for this is to build the wall using "Durowall" on every other run. That means tearing the wall down so let's look at what you've got before we go that far.

Is this CMU wall structural and load bearing? If so, is the cracking the usual 'staircase' kind, going up and over, or is it a sagged line (horizontal) or it it vertical?

Staircasing usually indicates either one end sinking or a sideways shear loading. It's usually the first though. In that case foundation work (screwjacking or mudjacking) may solve it. A sagged line indicated either a broken foundation or if at one end only a sinking foundation at that end. Same solution as above. Vertical cracking is a broken and separating foundation and will likely never stay fixed short of redoing the foundation under that wall completely with something stronger. The usual cause is a lack of rebar in the foundation- that was kind of common until the late 70's around here and maybe down there too.

I hope the info helps and when you're hungry try R.B.'s on Shem Creek in Mt. Pleasant across the new Ravenel bridge. I promise you'll love it!


Engineering Dude
Re: Cmu exterior wall with cracks

Mrs whitsie,
I am a structural engineer practicing in the tri county area of Charleston including Charleston, Dorchester and Berkeley county. There are numerous site conditions that require engineering assessment in our area, including V Zone areas in the Special Hazard Assessment Areas (related to flood zones) and Seismic considerations, not to mention poor soils. The major load bearing strata in our area is the Cooper Marl (which varies in depth across the low country) however most residential structures can be supported with less expensive foundation design types. It would be difficult and inadvisable for someone to provide qualified advice for your issue without knowing the specific conditions of your site, the construction details of your home foundation and knowing what loads your house has been subjected to. I would recommend you seek advice of a structural engineer who can coordinate with a civil engineer or geotechnical engineer to adequately address this issue.

Re: Cmu exterior wall with cracks

Don't know if the OP is still around after about 2 1/2 years since the thread started :eek: but welcome to another Sandlapper anyway. You should come up here where we've got some blue granite boulders of immense proportions to get in the way of our foundations :cool: No earthquake bolts in our older buildings though.


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