Recommendation on Foundation Repair

[pperlich]

I'm a mechanical engineer by day and a farmer by night. I have a barn with a failing foundation. At some point, someone did a lot of foundation work on this barn, and this failure seems to be in an area that was repaired/replaced. It has sunken about 1-1/2".

I'm thinking the only possible repair would be to jack up the barn, remove the old foundation and dig deeper and pour a new foundation.

Is there any other option?

red line is the location of the column where the foundation has failed.

 

[JoelTXCive]

Is the concrete section just a shallow strip footing, or are we seeing the top of a wall? Or the top of some other deeper foundation element?

 

[pperlich]

My guess is its a strip footing. I'll grab a shovel and dig a little to be sure.

This barn is in decent shape, but it does have a handful of issues like this that I would like to correct.

 

[JoelTXCive]

It looks like an unreinforced strip footing. If there were reinforcement in it, then I do not think we would see the large separation at the crack.

I'll let the more wise people comment, but perhaps just the end of the strip footing could be dug out and replaced with something more substantial?

 

[BridgeSmith]

If the foundation has been repaired before and is still sinking, it's likely the material in the top several feet doesn't have adequate bearing capacity, so you could be digging fairly deep to find adequate support for a footing. I'd suggest looking into micropiles or their specialized cousins made for basement/foundation wall shoring of houses.

If the foundation has stopped sinking and has been stable for 5 or 10 years, you could possibly lift the foundation and pour a high slump concrete mix in the gap. Alternately, you could lift the barn off of the foundation and install shims to bring it up. I worked with a guy many years ago who releveled an entire large ranch house with a similar issue. He used a couple hundred wood wedges made from 2x4s and a sledge hammer.

 

[jayrod12]

I'd be inclined to agree with Joel.

however, it would be tough to know what size to put back without a more in-depth knowledge of the framing scheme (therefore knowing how much load is actually coming down).

 

[SlideRuleEra]

At some point, someone did a lot of foundation work...this failure seems to be in an area that was repaired/replaced.
I'm thinking the only possible repair would be to jack up the barn, remove the old foundation and dig deeper and pour a new foundation.

Before spending more time and money on a repair that may or may not work, might be a good idea have a geotechnical engineer take a look to determine the reason for the (ongoing) settlement.

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[Once20036]

Is the photo taken inside the barn looking out towards the end wall / the red line?
Is the condition that you describe only in one location? Or is the photo indicative of the typical joint between the higher portion of the barn and the lower portion?

 

[SAIL3]

from the photo it looks more like that end portion moved laterally, hence the gap...that diagonal may be picking up some gravity loading and causing that lateral movement....I personally would postpone any immediate fix and monitor it since it looks like it has been there for quite a period of time....

 

[BridgeSmith]

Sail3's comment about the diagonal reminded me to add a caveat to my suggestions - be sure to account for the lateral thrust from that diagonal before doing anything that will release the pressure off of the end piece of the footing so it doesn't "kick out" on you. You could probably use that sill plate on top of the footing if the diagonal is attached (or can be attached) to it and it is in turn attached to the interior section of the footing.

It does appear that due to the break in the footing, a substantial portion of the barn is now being supported on just the small block of concrete at the end.

 

[JoelTXCive]

HotRod brings up a good point....

We are all spit-balling here, but the wood horizontal sill plate could be functioning as a tie holding the leg in?

 

[BridgeSmith]

"...sill plate could be functioning as a tie holding the leg in?"

...if it's attached to anything. My concern was that if it isn't, all that's holding that diagonal in place is friction of the piece of the footing. If that friction is removed by jacking the footing up, etc. it could it ugly in a hurry.

 

[pperlich]

Yes, the photo of the crack is taken on the inside of the barn looking out toward the red line in the 2nd photo.

This is the only location that has this problem that I can see.

It's hard to tell how long the crack has been there and if the settling has stopped or not because I have only owned this property for 1 year. Previous owner had it for 4 years and wasn't able to answer any questions I had about any tiling around the foundation or the state or age of the foundation. I have seen in general houses and buildings settling more in the last year in this area. We had a record setting wet year last year, and so far this year has been very wet as well.

I will check out the construction of the joints at the diagonal, the sill, and the column and report back.

 

[pperlich]

I was able to examine the problem area a little closer, and take some more photos. I think when the foundation was worked on the barn must have moved laterally several inches. Each post has a slight lean to it, and the sill plate is overhanging what I think is an original foundation wall. The post and diagonal at the location we are talking about are nailed to the sill plate. The sill plate appears to have shifted. A previous owner has added 2 light duty posts in an apparent attempt to stop the settling.