Compacting dirt for house pad

[be12hunt]

We are building up a house pad from dirt that was delivered in. Our builder said they prefer a process of lifting about 8” then compacting down to 6” and repeating. I relayed this to the guy doing our dirt work from the beginning, but just found out we are nearly 4’ up and haven’t done any official compaction. He said the weight of the skid steer(12,000lbs) would compact it enough.

Anybody have enough experience to say whether I should roll with it or make him cut it back down and start over?

[doright]

You could have a compaction test done

[Joe H]

You could have a compaction test done

This. It is not being done correctly.

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[be12hunt]

You could have a compaction test done

I was worried that a compaction test would only tell me the top layer, but could still be loose under.

[Drycreek3189]

It somewhat depends on the material used, but a skid steer doesn’t offer much compaction. The last two house pads I built I used my dozer to spread the dirt and grade it, but I used my backhoe with a full bucket of dirt to compact it. I wheel rolled it with my front wheels, and that bucket full of moist dirt would compact about 3” after the dozer had graded it out. I was using perfect material though, which is really what should go in a house pad.

[bakin7005]

It depends on the soil really. An engineer will know. Get the test done. If your builder is not all over this you may want to consider a different builder. Its early and you'll have a long row to hoe if his subs arent doing it the way he wants.

[OldRiverRat]

We have always used the same guy for dirt work
He uses the dump truck to compact as he goes



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[RJH1]

I had to tead down a pad and rebuild it once over this stuff. Probably the best pad in the area, cause i wanted to make sure I got it right. Several years later, no cracks, so i guess it worked. I would dang sure get it tested, or redo it, can lead to a bunch of problems later if it is not correct

[be12hunt]

It depends on the soil really. An engineer will know. Get the test done. If your builder is not all over this you may want to consider a different builder. Its early and you'll have a long row to hoe if his subs arent doing it the way he wants.

So we chose to pay for the dirt work and contract it out ourselves. The builder is just offering guidance on what they typically see.

We have always used the same guy for dirt work
He uses the dump truck to compact as he goes



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That was what the builder said is common. The dirt work guy said they kind of did that, but at one point I saw almost 80 loads in just random piles that weren’t spread.

[bakin7005]

So we chose to pay for the dirt work and contract it out ourselves. The builder is just offering guidance on what they typically see.

I would heed his guidance. If I was the builder I wouldn't want to build a house on an un-compacted pad.
The dump truck compacting is a common practice in OK but with a dozer moving the dirt, not a skid steer.
How much fill you talking about?

[mwk128]

I was worried that a compaction test would only tell me the top layer, but could still be loose under.

You are right about that. You could do test pits to test compaction deeper but that isn’t all that reliable. I would 100% make him pull it out and start over. Depending on how complete your construction plans are they may have the soil lift thickness and required comparison on them. If so you need to hold your dirt work guy to those requirements. Also if you’re in an area that requires building inspections you’ll be in trouble unless it’s done properly.

A skid steer isn’t near heavy enough to get good compaction. A loaded dump truck, roller, or something similar is needed. 6-inch compacted lifts, compacted with something heavy is what you need. Preferably compaction testing as it goes in too. Think about it, you’re setting a structure that costs several hundred thousand dollars on top of this dirt. The earthwork needs to be done right.

You’re dirt guy is blowing smoke up your *** and trying to get away with half a** work. Personally I’d fire him since he’s already shown he’ll cut corners and lay to your face.

[RCDuck]

It depends a lot on the soil type, but I'd be very skeptical of a skid steer used for compaction, especially if the soil has any clay in it. If he's just "building grade" with the skid steer, it isn't properly compacted.

It's also important that the soil has close to optimum moisture when compacting.... bone-dry dirt does not compact properly.

[WItoTX]

We are building up a house pad from dirt that was delivered in. Our builder said they prefer a process of lifting about 8” then compacting down to 6” and repeating. I relayed this to the guy doing our dirt work from the beginning, but just found out we are nearly 4’ up and haven’t done any official compaction. He said the weight of the skid steer(12,000lbs) would compact it enough.

Anybody have enough experience to say whether I should roll with it or make him cut it back down and start over?

HAHAHAHAHAHA that is what all earthwork contractors say. He is trying to get it done as quick as possible. They all do that. And it's wrong.

There are two ways to do it right. The ideal way:

The correct way is first to determine what the engineer says the fill needs to be compacted to. Your project drawings should show this.

Second, hire a testing firm to perform densities. They will run a proctor, establish what compaction is needed to achieve the engineers specifications. They will then dispatch a tester to come test based on the specifications provided by your engineer. Typically it would only be 1 test per lift for an area that small, but you pay per test. So you can in reality have 3 or 4 done.

The cheaper way:

Do a proof roll. Basically what you do, after going up your 8" lift, run a loaded dump truck over the pad. The soil should not roll, and the tires should not sink into the dirt. Also, the dirt should not "crack" when the dump runs over the soil.

Now, lets assume the earthwork guy gets everything compacted. If you have UG pipes or electrical going in, you NEED to make sure the plumber and electrical guy compact their trench when they backfill. Otherwise you will have settling, and you will get concrete cracking where the soil settled in the trenches.

I did materials testing a number of years. If you have any other questions, feel free to PM me. Good luck!

[Sticks&Strings]

So we chose to pay for the dirt work and contract it out ourselves. The builder is just offering guidance on what they typically see.







That was what the builder said is common. The dirt work guy said they kind of did that, but at one point I saw almost 80 loads in just random piles that weren’t spread.

That's not good. I would be leery. We use a dozer and about every 10" we roll the pad with a loaded dump truck. It really compacts it several inches. But each load is spread as it arrives. Never have more than about 4 loads at a time on the pad.

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[curtintex]

Nope. Skid steers, especially tracked, are designed for the least amount of ground pressure possible considering the weight.

You have some good advice above, follow it.

I build pads for stadiums, high schools, hospitals, shopping malls, big box stores, etc. Even built one for a house or two.[emoji6]


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