Undermined pier block

[John Kogel]

Is there a proven method for repair when fools have dug the soil away from a crawlspace pier block?

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[Mike Lamb]

Adding other columns and piers to help take the load off the one might be easiest.

[Marc]

I've gotten a few of those on a particular antebellum-style home near me. I do electrical work for them. I advise that the load first be shifted to temporary supports then dig the area down to soil having 2,500 Lbs/SF capacity then build up a pier from there. After that's done, backfill the hole.

I have a pocket penetrometer I use for this sometimes. The scale is tons/SF. You press it down into the soil until the ring on the tip is flush with the surface of the soil.

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Marc

[Jim Katen]

Is there a proven method for repair when fools have dug the soil away from a crawlspace pier block?

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45.19 KB

There are lots of ways. I was at a house with one of these a few weeks ago. An engineer was evaluating the house at the same time. He suggested building a retaining wall out of bags of fence-post concrete mix. Set the first one on a levelled off section of the ground and set the others on top of the first, pressing them against the vertical face of the soil as you go, forming a battered back wall. Re-arrange the vapor barrier on top of them and wait a few weeks for the concrete to absorb water from the soil & cure. Simple, quick, effective, and provides a good workout at the same time.

[Garet]

Whoa! An engineer with a pragmatic solution?

[Jim Katen]

Whoa! An engineer with a pragmatic solution?

I've known this guy for almost 20 years. He usually comes up with practical and creative soultions. His business card features the skill, "Lateral Thinking"

[kurt]

That's not a bad idea.

I see these things occasionally, and it's remarkable how little the soil does move. Even when soil is collapsed, there's rarely significant movement, point being, a retaining wall seems like it would work fine.

Would backfilling with sand (after the bag wall sets up) provide any additional value?

[John Kogel]

That's not a bad idea.

I see these things occasionally, and it's remarkable how little the soil does move. Even when soil is collapsed, there's rarely significant movement, point being, a retaining wall seems like it would work fine.

Would backfilling with sand (after the bag wall sets up) provide any additional value?

This hole was stable for quite a few years but. We have to be prepared for a tremor now and then in this part of the globe. I was alsp thinking a flood like a broken water main would destabilized the soil pretty quick.

Sack-rete poured in for backfill would set up harder than sand, but sand will let the water out. I think pulling some dirt from the surrounding crawl for baclfill would be good.

Thanks Jim, I was thinking a reinforced CMU retaining wall, but sandbags would be stronger and really stable. I think a sack of that redi-mix weighs about 80 lbs, tho.

[John Kogel]

Adding other columns and piers to help take the load off the one might be easiest.

I agree, but this particular beam has a butt splice right there. So I guess they would need two posts, a long and a short.

That's a nifty tool, Marc. Good for checking the mud down at the levee. []

[Mike Lamb]

Adding other columns and piers to help take the load off the one might be easiest.

I agree, but this particular beam has a butt splice right there. []

Bolt and glue a 2X sister both sides of the beam long enough to make everyone happy, then 2 screw jacks fastened to the beam and a suitable footing. I would try not to lug sand or concrete.

[John Kogel]

Adding other columns and piers to help take the load off the one might be easiest.

I agree, but this particular beam has a butt splice right there. []

Bolt and glue a 2X sister both sides of the beam long enough to make everyone happy, then 2 screw jacks fastened to the beam and a suitable footing. I would try not to lug sand or concrete.

OK, what if it's a chimney foundation? Well then you need to build a retaining wall. Thanks for all good answers.

[John Dirks Jr]

Is there a proven method for repair when fools have dug the soil away from a crawlspace pier block?

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Shouldn't that pier have a footing deeper in the soil? Or is it not needed because the location is a crawlspace and not expected to be exposed to freezing and heaving?

[Jim Katen]

Shouldn't that pier have a footing deeper in the soil? Or is it not needed because the location is a crawlspace and not expected to be exposed to freezing and heaving?

Not in a crawlspace.