How long should I let new ground settle before putting in posts on piers?

deezler

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If you roll it now, it will only compact the top foot or so, it won’t do much deeper down.

Yes but that might be enough to hold a concrete slab in place that will only hold some hay bales, right? This isn't going to be a precision workshop or factory floor, from what the OP said. Maybe we're all over-thinking this a bit. Plenty of pole barns have been built on uncompacted fill, haven't seen too many horror stories on the web about them.
 

deezler

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^ that said, if you DO go to the trouble of renting a large vibratory roller, you might as well get a dozer back out there too, and do it all in stages to get it correct.
 

Doughknob

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Yep i agree - should wait or dig down to undisturbed dirt. And here is the god part - you can easily dig down 7' with one of these
IMG_0575.JPG
The handle is common pipe thread. I got a section of pipe and a coupler and made my handle about 10' long. I used it to dig down 10' for a sump pump in the barn.

Slow going, but it beats waiting 3 years! Sometimes old fashioned hand tools rule.
 

fried1765

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Yep i agree - should wait or dig down to undisturbed dirt. And here is the god part - you can easily dig down 7' with one of these
View attachment 709895
The handle is common pipe thread. I got a section of pipe and a coupler and made my handle about 10' long. I used it to dig down 10' for a sump pump in the barn.

Slow going, but it beats waiting 3 years! Sometimes old fashioned hand tools rule.
Only 6" diameter, so not a large enough footprint for post support.
 

rScotty

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I agree with all the above. For standard building, it's a lot better to put poles and slabs on soil that has been sifted, amended, and then compacted in six inch lifts. But there are other ways that can work if you will think outside the box and take some risk. Judging from that photo of your site you don't mind the risks. There's trash, rocks, and what looks like old concrete in your site prep. You wouldn't have those unless you were willing to gamble. The trick is to do it differently...

25 years ago we built a small heavy 2-story 20x50 barn on uncompacted fill that was way worse than yours.

You do have to drill down to form pockets for your piers in undisturbed soil. We found a a local guy who drills shallow wells to do our post holes. He had a nice drill rig on a flatbed truck with hydraulic feet and no problem drilling down as deep as wanted. The well rig bit was able to slice right through some rocks too. We went down ten or 12 feet with pretty big diameter holes...I forget just how big, maybe 12 to 16" ... anyway big enough so that we could pour concrete around the creosoted poles once we got them in and positioned.

Same for slabs. You can't put down a standard do-it-yourself home builder slab on uncompacted ground and not expect it to heave and crack.... but if you are willing to compact the top foot or two of soil you can put a slightly more sophisticated slab called a floating or self-supporting type right there in your barn. Find a local civil engineer who has has designed piers and slabs for sandy areas. They know how it's done.
What you will get from the PE will be a drawing of a slab with lots of rebar, and might be thicker than most slabs especially if it is designed with a waffle pattern bottom. It might or might not connect to the piers. But those are just details.

I put a couple of slabs like that in our pole barn some 20 years later when I turned part of the barn into a machine shop & wanted a concrete floor - and they are doing just fine. No cracks, no shifting.
rScotty
 

4570Man

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I agree with all the above. For standard building, it's a lot better to put poles and slabs on soil that has been sifted, amended, and then compacted in six inch lifts. But there are other ways that can work if you will think outside the box and take some risk. Judging from that photo of your site you don't mind the risks. There's trash, rocks, and what looks like old concrete in your site prep. You wouldn't have those unless you were willing to gamble. The trick is to do it differently...

25 years ago we built a small heavy 2-story 20x50 barn on uncompacted fill that was way worse than yours.

You do have to drill down to form pockets for your piers in undisturbed soil. We found a a local guy who drills shallow wells to do our post holes. He had a nice drill rig on a flatbed truck with hydraulic feet and no problem drilling down as deep as wanted. The well rig bit was able to slice right through some rocks too. We went down ten or 12 feet with pretty big diameter holes...I forget just how big, maybe 12 to 16" ... anyway big enough so that we could pour concrete around the creosoted poles once we got them in and positioned.

Same for slabs. You can't put down a standard do-it-yourself home builder slab on uncompacted ground and not expect it to heave and crack.... but if you are willing to compact the top foot or two of soil you can put a slightly more sophisticated slab called a floating or self-supporting type right there in your barn. Find a local civil engineer who has has designed piers and slabs for sandy areas. They know how it's done.
What you will get from the PE will be a drawing of a slab with lots of rebar, and might be thicker than most slabs especially if it is designed with a waffle pattern bottom. It might or might not connect to the piers. But those are just details.

I put a couple of slabs like that in our pole barn some 20 years later when I turned part of the barn into a machine shop & wanted a concrete floor - and they are doing just fine. No cracks, no shifting.
rScotty

I agree you could drill piers and make it work. But probably more expensive than digging it back up and rolling it in right.
 

ROUSTABOUT

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I've got one here 30vyears old 36x48 filled one day and started building. I've learned asking advice is not always a good thing. Most messes I've been in are from listening to "good" advice. Sounds like you need to get busy building. Just do the best you can with what you got.
 

quicksandfarmer

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Yep i agree - should wait or dig down to undisturbed dirt. And here is the god part - you can easily dig down 7' with one of these
a
The handle is common pipe thread. I got a section of pipe and a coupler and made my handle about 10' long. I used it to dig down 10' for a sump pump in the barn.

Slow going, but it beats waiting 3 years! Sometimes old fashioned hand tools rule.
I have one of those and have gone as deep as 10'. It does get to be a chore when you have to lift out 10' of iron pipe plus a load of dirt for each load. But it's doable.
 

quicksandfarmer

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I once lived in a city neighborhood that was all built on fill. The standard method was to use helical piers to support the foundation. Some of my neighbors had to go down 30 or 40 feet to hit soil that would support a load and I seem to recall hearing of one that was 60' down.
 
 
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