Pole building foundation question

[rademamj1]

Im guessing they are compacting it just a few inches at a time?

You are very close on your statement. The tracked skid steers i saw building foundation pads, would spread a truck load of select fill, then compact that load,, while the next truck load is moving into dump position. And repeatedly....until the pad reached its planned 28" thickness. It was for a 40'x75' pole barn, requiring 145 cubic yards fill, and was completed in just over 10hrs work.

So you really don't spread all the 145 cubic yards of fill first, and then compact with the tracked skid steer. Its done incrementally, by compaction of each truck load as it is delivered.

 

[mikester]

Footings should be on undisturbed subsoil. If you place footings on fill hire an engineer to look at your soils and make a recommendation on fill placement and compaction procedures.

If you don't have a clue hire the engineer to supervise the fill and compaction process.

I've seen far too many half a$$ed compaction jobs and heaving foundations and floor slabs to take the recommendation of some contractor who just wants in and out in the quickest amount of time in order to cash your hard earned cheques before you can put a stop cheque order in place.

 

[Egon]

Proper compaction and looking good are two different things.

 

[etpm]

Footings should be on undisturbed subsoil. If you place footings on fill hire an engineer to look at your soils and make a recommendation on fill placement and compaction procedures.

If you don't have a clue hire the engineer to supervise the fill and compaction process.

I've seen far too many half a$$ed compaction jobs and heaving foundations and floor slabs to take the recommendation of some contractor who just wants in and out in the quickest amount of time in order to cash your hard earned cheques before you can put a stop cheque order in place.

About 20 years ago I had built for me a building destined to be a machine shop. One of the things the machines could not tolerate was an unstable foundation. I spoke to the county building department about this. They required ANY slab poured on grade to be on undisturbed soil after a certain amount was removed from the top. Loose soil, leaves, branches, duff, etc. But after that requirement any leveling before the pour could be done would only be done by removing soil or having engineered compaction.
As it turned out it looks like the county has good requirements. My slab has survived the heavy machines on it during an earthquake. One machine, while it weighs only 8000 pounds, sits on only 4 feet, each foot seeing only 125 PSI. But the footprint of the machine is only 2 by 4 feet.
I am very happy the county rules are what they are. These rules are part of the reason that machine can hold plus or minus one ten thousandth of an inch tolerance all day, every day. An unstable foundation would not allow this.
Yeah, my example might be extreme, but a pole building can't have rocks subject to freeze thaw motion supporting it. Freezing water moves huge rocks large distances over time. Having a concrete footing below the freeze line, on undisturbed soil, makes all kinds of sense.
Eric

 

[Larry Caldwell]

The foundation of a pole barn is at the bottom of the hole. With a 4' frost line, dig a 4.5' hole, dump 6" of concrete in the bottom, and there's your foundation. Concrete walls between poles are retaining walls, and need to have a retaining wall footer. The footer in this case would extend inside the building so fill would sit on it to hold it down. For a 4' retaining wall holding compacted fill, the footer would be about 3' wide, with rebar hooks that extend up the wall. It doesn't need to be connected to the building at all, though people often drill through a post and run rebar at the top to keep things sort of lined up.

 

[Farmer495]

Footings/ poles go into the undisturbed soil. When I built I was on a 2 foot difference, my down hill poles are really two feet longer than the uphill ones. Onces the poles were all set, then I put and compacted fill.

 

[LouNY]

That's your thinking. But you have never actually tried using a tracked skid steer for foundation pad construction, or you would not be saying that.

He is also a long way north of central Texas.

The contractor desiring to put in stepped footers and a sile wall is doing the proper base how well he compacts the fill inside will determine how well the concrete floor works or if it cracks and tilts.
Also a post and beam structure would amount to a pole barn on poured walls

 

[forgeblast]

I'm planning to construct a 48 wide x 40 deep pole building on a site that has a moderate slope. So, the floor level at the front of the building would be just above grade at that location, and floor level at the back of the building (40 feet back) would end up being be about 4 feet above the grade at that location. In other words, the grade slopes down as you go from front to rear.

I do want to have a foundation wall, as opposed to putting poles in the ground. Location is Wisconsin, so planning for a 4 foot frost depth is required.

I'm getting quotes from various contractors. One contractor proposes to pour taller foundation walls at the rear, about 8 feet total wall height (4 feet of wall below grade and 4 feet above). Sidewalls would "stairstep" to only being 6-ish feet tall (2-ish feet above grade), and front foundation wall would be 4 feet tall (mostly/all below grade).

Another contractor proposes to use a uniform 4 foot tall foundation wall all around, but also install crushed rock on the rear and sides, underneath the concrete foundation wall, to a depth of 4 feet below grade.

I'm sure the first method is "better" (and of course more expensive). But I'm wondering if the second crushed rock under concrete method is "adequate"? It would obviously save a lot of the concrete cost, but I want my building to be stable and long-lasting.

not sure if other people mentioned it but its sounds like the last foundation they are recommending is a rubble foundation. I have used them before and have had no issues in pa. My first I dug down below frost level, and sloped one side to daylight. Put in some 2b and packed it. then put in 4' perforated pipe, and more 2b, until i was 1 1/2 feet from the top, put in tarpaper, and added rebar. poured my foundation pad right on top. Then built 1' thick stone walls for my 10x10 shed, it has a second floor in it), no movement etc. The larger building we are working on now will be a 16x20 sap house. Same way rubble and fieldstone walls. These walls will be about 4' high then wood ontop depending on how much stone we have left. Frank lloyd wright used it in a bunch of his houses.

 

[Larry Caldwell]

Frost heave is from freezing water. If your rubble foundation sheds water, it probably will never heave.

 

[Egon]

Frost heave is about capillary action that some soil types will support.

 

[Egon]

I have never heard of the crushed rock method up north. Water will get into the rock and freeze, thaw will make that part of the foundation move around. I'd not do the rock method.

Crushed Rock drains well. The freeze will not be a problem.

 

[Egon]

I can't imagine a worse machine to compact soil then a compact skid steer. Nothing with tracks should be used to compact soil. Tracks spread the weight of the machine over a large area so it floats on the soil.

There is a myth that tires, tracks or so forth provide proper compaction. Sounds good, looks presentable but may approach 90% proctor which is far from desirable.

 

[LouNY]

https://www.google.com/url?sa=t&rct...tire-rollers&usg=AOvVaw1KDh3_eFWeRvdpveMJlMct

 

[EddieWalker]

There is a myth that tires, tracks or so forth provide proper compaction. Sounds good, looks presentable but may approach 90% proctor which is far from desirable.

There are machines designed for compaction that use tires.

A home owner can do a decent job with the front tires of a tractor if they build up the soil in small lifts, and work it over and over again, if the moisture in the soil is correct.

Ideally, you need a machine that vibrates, has a lot of weight with a small footprint, the proper moisture content for the soil, and lifts based on the size of the machine doing the compaction.

Nobody can get compaction with a machine with tracks. They can make it look pretty, and it's gonna be compacted enough to walk on it, but if you drive anything over that soil, it's obvious that it's not compacted.

 

[4570Man]

There are machines designed for compaction that use tires.

A home owner can do a decent job with the front tires of a tractor if they build up the soil in small lifts, and work it over and over again, if the moisture in the soil is correct.

Ideally, you need a machine that vibrates, has a lot of weight with a small footprint, the proper moisture content for the soil, and lifts based on the size of the machine doing the compaction.

Nobody can get compaction with a machine with tracks. They can make it look pretty, and it's gonna be compacted enough to walk on it, but if you drive anything over that soil, it's obvious that it's not compacted.

Have you actually tried compacting anything with a tracked skid and and a bucket full of dirt? Done properly it works reasonably well. The ground pressure is actually way higher than simple math would imply. For starters the front roller is carrying most of the load. It’s not evenly applied over the whole track. Second the rollers pound the track pads into the ground that brings the load to a fairly high psi. No it’s not a vibratory roller but it’s good enough for most jobs. I’ve driven cement trucks and dump trucks over jobs I’ve skid steer compacting and they barley leave a track. I think we can all agree nothing beats a vibratory roller. Short of that driving a loaded dump truck back and forth would be the next best option. But a tracked skid steer will do equally as good as anything else in the same weight class.

 

[deezler]

Good advice in here so far on best concrete foundations and compaction techniques. I am confused why you are calling it a pole barn when you want to build walls atop a full concrete foundation. This would be better termed as "stick framing" than as a pole barn.

The strength of a pole building comes from having uber-treated 6x6 posts going 4 feet (or more) down into well compacted or virgin soil, every 8 feet around the perimeter of the building.

Curveball: why not just hire a landscaper/excavating contractor to build you a full level dirt pad (at least 10' bigger than the building on all sides), properly compacted in 6" lifts or less, and let it sit for a year. Re-compact it and then you have a stable pad ready to build a conventional pole barn atop.

 

[Egon]

There are machines designed for compaction that use tires.

A home owner can do a decent job with the front tires of a tractor if they build up the soil in small lifts, and work it over and over again, if the moisture in the soil is correct.

Ideally, you need a machine that vibrates, has a lot of weight with a small footprint, the proper moisture content for the soil, and lifts based on the size of the machine doing the compaction.

Nobody can get compaction with a machine with tracks. They can make it look pretty, and it's gonna be compacted enough to walk on it, but if you drive anything over that soil, it's obvious that it's not compacted.

There are machines designed for compaction that use tires.

A home owner can do a decent job with the front tires of a tractor if they build up the soil in small lifts, and work it over and over again, if the moisture in the soil is correct.

Ideally, you need a machine that vibrates, has a lot of weight with a small footprint, the proper moisture content for the soil, and lifts based on the size of the machine doing the compaction.

Nobody can get compaction with a machine with tracks. They can make it look pretty, and it's gonna be compacted enough to walk on it, but if you drive anything over that soil, it's obvious that it's not compacted.

There are machines designed for compaction that use tires.

A home owner can do a decent job with the front tires of a tractor if they build up the soil in small lifts, and work it over and over again, if the moisture in the soil is correct.

Ideally, you need a machine that vibrates, has a lot of weight with a small footprint, the proper moisture content for the soil, and lifts based on the size of the machine doing the compaction.

Nobody can get compaction with a machine with tracks. They can make it look pretty, and it's gonna be compacted enough to walk on it, but if you drive anything over that soil, it's obvious that it's not compacted.

Yes, rubber tired compactors are available. Many different types For different materials. They work well in areas that would suffer damage from tracks or the steel lugs of some of the compactors.The tires are designed for compaction. Much different than the ordinary tractor tire.Some are set up so tire pressures can be varied and they may have water tanks to spray the tires.

As for ordinary tire/track compaction about 90% percent of proctor is what will be achieved in a reasonable amount of time.

For some materials the standard high heeled ladies shoe provides excellent compaction.

 

[adlertom]

Good advice in here so far on best concrete foundations and compaction techniques. I am confused why you are calling it a pole barn when you want to build walls atop a full concrete foundation. This would be better termed as "stick framing" than as a pole barn.

I suppose that the better terminology for my post would have been "post-frame construction", which can have posts either in the ground, or anchored to a foundation.

Around here, it seems that when people talk about "stick framing", they are generally referring to construction using smaller sized boards i.e. 2x4s, etc. But perhaps the nomenclature varies in some areas.

I suspect that stick framing for my project would be more expensive than post-frame.

 

[deezler]

Ok I gotcha. Sure, you can anchor 6x6 posts atop a foundation and build a normal style pole barn that way. But I have to question why - you are making a hinge point where the posts anchor to the foundation. Just seems less sturdy. Whereas when you stick frame, which it sounds like we concur on, you have an entire 2x6 bottom plate repeatedly anchored into the foundation, and a much more sturdy box frame of a building constructed atop it.

Yes, 2x6 stick framing typically costs more than a pole building, but it's primarily because of the need for a full conventional foundation. You are doing that anyway, sounds like. I would price it out to see how much building your side walls out of standard 2x6 framing would cost, in comparison to buying expensive 6x6 poles that are now somewhat tricky to anchor to the foundation. You can still use the same roofing trusses atop a standard 2x6 framed wall. Only difference is, your building will be stronger, easier to insulate, wire, and so on.

But I would also still consider just making a big dirt pad that is somewhat larger than the building size, properly compacted in 6" lifts, and then just put your poles in the ground normally. I bet this would be cheapest overall.

 

[rademamj1]

There are machines designed for compaction that use tires.

A home owner can do a decent job with the front tires of a tractor if they build up the soil in small lifts, and work it over and over again, if the moisture in the soil is correct.

Ideally, you need a machine that vibrates, has a lot of weight with a small footprint, the proper moisture content for the soil, and lifts based on the size of the machine doing the compaction.

Nobody can get compaction with a machine with tracks. They can make it look pretty, and it's gonna be compacted enough to walk on it, but if you drive anything over that soil, it's obvious that it's not compacted.

I would never ever use any soil as a fill for a concrete foundation because of the high organics. The best choice is a select fill, which has been washed and is free of organics, and is fine grained trending mostly to a silt sized particle. You typically find these type fills in river bends where large and now exposed silt bars are deposited and the naturally washed and recovered fill is sold by truckloads. It is relatively dry to visual eyes, but it does retain water by surface adhesion on each silt particle, giving a perfect moisture content for the overall select fill.

Compaction of such a selected fill occurs very well using a typical 10,000lb tracked skid steer. But you should spread and compact with each truck delivery, not dump say 20 truck loads first and then spread and compact all of it. Even wheeled vehicles struggle greatly when that occurs, resulting in uneven compaction surfaces. Usually you can build such a foundation as fast as the trucks deliver, or about 1 to 2 days.