Jump to content

Undermined pier block


Recommended Posts

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.

Click to Enlarge
tn_2013112913034_002.jpg

28.64 KB

Marc

Link to post
Share on other sites

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

Click to Enlarge
tn_20131129124457_undrminedpier.jpg

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.

Link to post
Share on other sites

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?

Link to post
Share on other sites

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.

Link to post
Share on other sites

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. [:)]

Link to post
Share on other sites

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.

Link to post
Share on other sites

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.
Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...