How deep is deep enough

[CharlieTR]

I don't think deeper will add any strength to the structure. For mine (in Ladonia, TX) I just poured 1 foot of concrete below each pole, backfilled with concrete, then a couple of years later added a concrete floor. It seems to me that the massive cracks we get here are limited to pasture areas, rather than real close to structures. A little rain, dew, shade is enough to keep the soil intact around the barn, at least not nearly as bad as fences.

 

[DavidPerry]

Yes, I was planning on using 2 3/8" OD pipe for the uprights. I'll add a concrete floor. Maybe it will all be a non-issue with the floor down.

Thanks for your input.

 

[DavidPerry]

I looked at some pipe this evening I had driven 3' into the ground this last spring. I could lift the post out without tools. The posts in 3' of concrete are still steady. I think I'll go with 4' holes and a bunch of concrete. Hard to believe ground can crack and split this much.

 

[wroughtn_harv]

One of the biggest problems we have in my line of work is trying to find that combination that will keep a post located over time.

In sandy soil there isn't the problem with heave or better yet, expansive soil contraction-expansion that we have to deal with in our heavy clay.

My son in law saw a bull snake dive into a crack by his house. He grabbed the tail and tried to pull it out of the crack. The snake was too strong and finally son in law let go. The snake disappeared and not a part of him could be seen.

Probably the best example of the way we have to engineer and build things just because of our soils is our street construction. Most parts of the country a simple base preparation and then blacktop is standard for most residential and rural roads. Here in the cities the soil is first stabilized with lime treatment and then serious concrete is poured. And this is for streets in subdivisions. On the major highways it's even more involved.

When the soil presents such problems for major construction then simple things like setting fence posts or poles for barns and shops have to be treated differently as well.

One of my clients has forty plus acres in Rockwall County. His house sits on a rise (we don't have hills much less mountains). His elevation will change six inches during the year as we go from wet to dry. When they built his house they went down forty plus feet with the piers and never found anything but clay.

 

[DavidPerry]

Today I removed the last of the pipe from this area tackling the only one of the bunch that didn't just fall out of the hole. This was firm and not in a hurry to come out. I had driven it 7ft below grade.