Pole barn/site prep question

[seabreeze]

We’re getting ready to build a pole barn as a garage/workshop/tractor/lawn equipment catch-all. My question is about site prep. We will be pouring a concrete floor for the entire footprint.

Two different estimates:
A - remove up to 10” of topsoil, backfill with sand and compact to grade, add 3” compacted crush and run above grade.
B - remove 1.5”-2” of topsoil, backfill with compacted asphalt millings to a few inches above grade.

Based on everything I think I know about site prep, I’m leaning heavily towards estimate A. Agree? Disagree?

If it matters, we are on high land with well-drained soil. We’ve had 4” of rain this week and had 6” last week, and there isn’t a puddle on the place.

Thanks for your thoughts.

[house]

Where are you located? what is the dirt like? Where I live in California if I were in your position I would just remove 1-2 inches of top soil then add the sand and crush(which I assume is like gravel?).

I would also comment that when in doubt the higher above grade the better, I found in my barn that when I started pouring concrete to get enough fall I was not high enough. minimum is 1ft in 100 better is 2ft in 100, when you get to the edge of you still want to be above grade an inch or so

[seabreeze]

@house, eastern seaboard, Mid-Atlantic, sandy soil

[luvmyhackney]

Does removing 2” of soil get you to good stable soil?

If not, I would go with estimate A.

[seabreeze]

Exactly what I was thinking. Thanks for weighing in.

[Live_Wire]

Estimate B would work, but it could also fail. Estimate A is more guaranteed.

[goodhors]

Better A than B. Brother the barn builder always recommends raising the ground level above surrounding area, before building. He raised our ground about 5ft, which settled over winter, got the air out, down to about 4ft. We have never regretted putting in all that fill! Then once the “shell” was up we added more dirt, watered inside, to settle that added dirt.

When we finally did stall floors with layers of draining material, poured cement floors, all that dirt was WELL settled, packed hard. The cement has two cracks after MANY years, which we blame on the woodchuck who tried to move in under the cement. We got him, but not quick enough!

My thought is you are not allowing enough time after dirt work for things to truly settle. Rain or wet surrounding dirt can change how that prep work now absorbs or directs water flow, drainage from the fields. I definately would want more dirt added, to raise the floor level! We have learned that higher is ALWAYS better than level!!

Pouring cement before things are well settled will cause a lot of cement cracking in the future, as the ground under continues to settle in place.

[seabreeze]

Thanks for the info. Will pass along to DH.

[seabreeze]

@goodhors, when you let the dirt settle, had you compacted it first? Curious to know how rolling and compacting makes a difference. Thanks!

[clanter]

unless the back fill is mechanically compacted it takes dirt a period of about 7 years depending type of soil to settle to a natural state

[goodhors]

@seabreeze The settling over winter, was caused by the weather. Hard rains, heavy snow melting into the fill. The machinery on the fill was in early spring. I am pretty sure there was no big compacters, more of skidsteer setting poles, trucks with lumber. We did use small compactors in the stall areas to get the layers down firmly.

[seabreeze]

@clanter, Estimate A includes mechanical compacting of backfilled sand and crush and run.

[clanter]

personally what I do not like about A is the 10 inches of sand as sand can be easily displaced by erosion or rodents

We used compacted road base material for the base of our barn

However if sand is commonly being used in your area by reliable contractors then it must be acceptable

I suggest whenever there is to be hauled in product such as dirt, sand or gravel that you are paying for to request copies of the haul tickets. Each load should have a scaled weight ticket, And these days I would set up a recording system to verify that the trucks did deliver the material.

[seabreeze]

@clanter, I’m calling it sand but it is more of a sand-clay mix. As you mention, it is commonly used in this area. My husband is retired and will be here watching every grain of sand delivered, I have no doubt. Thanks for the feedback.

[clanter]

have him log the trucks with as much information as possible so you do not get into the issue my attorney did when he had a nationally known barn builder bill him for well over twice the amount of backfill then what was actually brought in

[Mosey_2003]

A, but why the sand under the rock? I’d do the bedding stone first.