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

[SnagDump]

And, if you like facts regarding ground pressure and compactive effort here are some:

D6 Cat Dozer, standard tracks, 50,733 lb. Ground pressure 7.9 psi

Ford F250 5700 lb. LT285 tires ground contact patch approx 46 sq in. per tire or 184 sq. in. total for all four. 5700 / 184 = 32 psi.

Towed sheepsfoot rollers 200 psi and up. Way up.

 

[4570Man]

And, if you like facts regarding ground pressure and compactive effort here are some:

D6 Cat Dozer, standard tracks, 50,733 lb. Ground pressure 7.9 psi

Ford F250 5700 lb. LT285 tires ground contact patch approx 46 sq in. per tire or 184 sq. in. total for all four. 5700 / 184 = 32 psi.

Towed sheepsfoot rollers 200 psi and up. Way up.

You really need a vibratory roller to do a good job compacting.

 

[BoylermanCT]

Your poles need to be set on virgin soil, not compacted soil, so dig down to that level for each post. I just finished a 30x40 pole barn. My plans called for a 4" thick 16" round concrete cookie at the bottom of each pole to prevent the pole from sinking into the ground. We had to raise the rear elevation 3' to match the front elevation. We did it in 4" layers and a vibrating plate compactor plus all of the tractor traffic moving the soil. Then we flooded each layer with water and once up to final grade it sat out in the weather for 6 months before the roof went on.

 

[Firemanbuck]

The best option as mentioned above, is to cut back into the hill and make sure the footprint of the building is all on native soil, then compact the native soil before building your pole barn. Having half the building on native and the other on poorly compacted fill will result in differential settlement between native and fill. Either retain the cut slope or knock it back to 2:1 (H:V) if you can.

Tracked equipment is NOT suitable for proper compaction of the soil because of low ground pressure. Use a smooth drum vibratory roller for compaction if the soil is granular (sand and gravel), or a sheepsfoot if it is cohesive (silt and clay). Keep your lifts thin 6-8 inches and avoid clasts larger than 6 inches in diameter (we usually recommend <3 inches). You can test the compaction using a tile probe and pushing it into the soil with your body weight. It should go in less than an inch for properly compacted soil.

If you can, get a single-shingle geotech or engineering geologist out to give you some pointers.

/engineering geologist

 

[s219]

For pole barns on hills where fill is needed, I like to drill the post holes first, install the footings and posts, and frame/square up the structure (minimum posts and girts, and one skirt board) before backfilling the post holes. Then you can think about backfilling and leveling the site with a self-compacting material (any screened gravel 3/4" or below in size -- I prefer #8, which is a pea size). Heck, you can build the entire barn before backfilling and leveling the site if you want, as long as you can get a machine with a loader inside to bring in the gravel later.

This is the fastest/cheapest method to move forward with the pole barn method. When you have to start worrying about compacting a base and pouring a slab, then you begin to lose many of the benefits off the pole barn method. People still do it, which is fine, but you lose some of the time and cost benefit.

Too many times I have seen someone prep the site too much and then have to deal with compaction issues, or footing issues, or have to drill post holes through the gravel base they just put down (which is more work).

 

[JWR]

Yeah, Eddie is correct. If you have driven by or been around a construction site it might look like bulldozers are spreading soil and compacting but they are not doing the compacting part. I spent 37 years as a land surveyor on all sorts of construction sites, I also did nuclear machine density testing. The pic Eddie posted of a vibratory sheep’s foot roller is the most common tool.

This horse is long since dead and I will make no further comments after today. Nothing wrong with opinions.

No, Eddie is not correct in the context of getting ground compacted suffieciently to get on with most projects. I hear all he & others have said about the low per square inch soil pressure of the dozer, etc, etc.
Now, in this current context, NOT about buildings or foundations: Sure sheeps foot rollers and all sorts of equipment do some serious packing of soil on relatively flat or gentle slope places. Nationwide you have huge acreage of VERY steep road edges, berms, embankments, earthen dams, pond sides, farming soil movement, etc. where no roller can or ever will set foot. Where a sheepsfoot packer could not get to, much less operate. Guess what is used? The dozer my friends. Adequate compaction for the needs at hand are not always foundations nor high soil pressure requirements. The world uses bulldozers.

Dozers have done more soil compacting than any other machine in our lifetime and nothing said here refutes that. The next nearest competitor has never been mentioned or put forth.

 

[MasseyFerg231]

OP- if you don’t care and money doesn’t matter, roll the dice and go ahead and build/pour as-is. Maybe it will suit your needs and budget.

If you want it to last, and be of use in the future; remove the fill, clean the fill, place and compact the fill along with using grading and gravity to get rid of any standing water near your structure.
If you ever want to enclose the structure, go ahead and add a vapor barrier prior to pouring.

Good luck!

 

[MasseyFerg231]

One other note, a compaction test or proofroll is only a snapshot of that particular time. Meaning that you can have a perfectly placed and compacted product, then weather hits and it turns to crap(or vice versa). We have had several parking lots on jobs(25 acres plus) where conditions were not optimal, but we stayed off the subgrade and allow winter to pass and kept checking until the site improved enough to place aggregate and paving.

 

[EddieWalker]

This horse is long since dead and I will make no further comments after today. Nothing wrong with opinions.

No, Eddie is not correct in the context of getting ground compacted suffieciently to get on with most projects. I hear all he & others have said about the low per square inch soil pressure of the dozer, etc, etc.
Now, in this current context, NOT about buildings or foundations: Sure sheeps foot rollers and all sorts of equipment do some serious packing of soil on relatively flat or gentle slope places. Nationwide you have huge acreage of VERY steep road edges, berms, embankments, earthen dams, pond sides, farming soil movement, etc. where no roller can or ever will set foot. Where a sheepsfoot packer could not get to, much less operate. Guess what is used? The dozer my friends. Adequate compaction for the needs at hand are not always foundations nor high soil pressure requirements. The world uses bulldozers.

Dozers have done more soil compacting than any other machine in our lifetime and nothing said here refutes that. The next nearest competitor has never been mentioned or put forth.

You are probably correct in playing a word game of saying that dozers have compacted more soil then any other machine. But you should also add that it compacts the soil poorly and that no building should ever be built on soil compacted by a dozer. You also might want to add that soil compacted by a dozer is much more likely to wash out and erode ten times faster then a road that is properly compacted. But maybe that's just a small detail in the grand scheme of being right.

 

[4570Man]

You are probably correct in playing a word game of staying that dozers have compacted more soil then any other machine. But you should also add that it compacts the soil poorly and that no building should ever be built on soil compacted by a dozer. You also might want to add that soil compacted by a dozer is much more likely to wash out and erode ten times faster then a road that is properly compacted. But maybe that's just a small detail in the grand scheme of being right.

If you did it in lifts and tracked in each lift the dozer would compact it good enough for a barn. If you just shoved the dirt out the dozer isn’t going to compact it very much.