Possible road block for pole building, looking for input

[JasonF]

I am in the process of prepping my build site to have a 32x38x12 pole building put up in the rear of my property. In talking to the excavator that come by last night to give my some estimates I find out that the area I want to put my barn in was used for dumping fill 25+ years ago. Said they dumped a lot of concrete and tree stumps n such. I cleared the area of brush this spring and did notice some smaller pieces of concrete at the surface which I dug up and tossed.
I was planning on paying a contractor to put this barn up but what happens if they cant get holes into the ground? What could I do ahead of time to make sure things go smoothly?

There could also be the option of stick building the garage on a slab and a rat wall, just dont know what kind of restrictions my township has on slab size yet? Anyone have any idea the cost comparison of a pole built to a stick build gargage? The average quote I was given for my pole barn build was ~$26,000 if that helps with what a slab built garage would cost.

What was included in my pole barn estimates;
32x48x12 building
metal on walls/roof
4/12 pitch, must have under 18' peak ht
4" concrete inside and a 4" 30'x 24' concrete approach
2 12x10 overhead doors, 2 window, 1 entry
overhangs all around

Any suggestions are welcomed!

 

[NHBandit]

Third option which is what I did was to build a pole barn on a slab. Pour the slab first and build on top of it. My property is all Limestone ledge just under the dirt and putting that many holes in the ground 3' deep would have been an absolute nightmare. The pole barn company I dealt with, National Barn Company, charged the same price to build on top of the slab as they would have to do it the traditional way. Pics tell the story better than I can. FWIW I paid right about 17.5k for my 30x40x12 including the slab, 2 10x10 doors, fully insulated metal pole barn not including electric which I did myself. http://www.garagejournal.com/forum/showthread.php?t=188161

 

[justanengineer]

Third option which is what I did was to build a pole barn on a slab. Pour the slab first and build on top of it.

The problem with that is that the OP is in Michigan and has to worry about frost heave. My brother's got a small old horse barn in Northern NY that was built how youre describing, and at some point in time the ground heaved several inches, broke the concrete, and pitched the walls outward onto the ground. Its still standing, but barely. Personally, Id be amazed if even in TN you could leave the heat off for more than a week or two in a shop built like that and not have major issues. Granted, heating the shop will help or cure those problems, but everybody goes on vacation once in awhile.

 

[NHBandit]

The problem with that is that the OP is in Michigan and has to worry about frost heave. My brother's got a small old horse barn in Northern NY that was built how youre describing, and at some point in time the ground heaved several inches, broke the concrete, and pitched the walls outward onto the ground. Its still standing, but barely. Personally, Id be amazed if even in TN you could leave the heat off for more than a week or two in a shop built like that and not have major issues. Granted, heating the shop will help or cure those problems, but everybody goes on vacation once in awhile.

I don't have any heating system. The ground dosn't freeze here in Tennessee. I think last Winter we had maybe 2 days that didn't get over 32 degrees during the day. Which is part of the reason why my property taxes are $400 a year as opposed to 5k at my old place in NH. Minimal road maintenance here because they don't have to fix potholes & huge cracks due to frost heaves every couple of years. I had to go back to NH last week for a wedding and driving down the road I used to live on I was reminded of this.. It was completely repaved 2 years ago and now it's like driving down railroad tracks. The roads here in East Tennessee are smooth as glass and haven't been touched in years. You make a good point for Jason to think about though considering his location.

 

[sands35]

Do you know how many tree stumps are in there? Sooner or later they will decompose and create settling.

To minimize your financial risk (i.e., not entering into a contract) you could drill the holes yourself. OR you could cut the contract into 3 parts (typically they 2 for garage builds, 1/2 up front and 1/2 on completion). Make the 1st payment for the ground prep and holes only. If it doesn't work, you aren't out a lot of money.

You could also do a frost protected foundation. They are only ~2' thick at the perimeter, about 1' below grade. But that's a stick building, not a pole building. Pole works because the posts carry moment (lateral and bending) loads really well at ground level. Stick construction requires sheeting to carry the lateral loads.

 

[BD1]

I'm in Northern Illinois. Nearby equine stable just had a metal pole building erected for hay storage. It is 20' x 28'. All they did was grade level, add stone, and lay down 6''x6'' timbers for the base FLAT. Yes, just laid down wood and built on top of the wood. I never saw this before.

 

[JasonF]

I have seen unheated garages here in Michigan built on slabs before and they always looked to stay in pretty good shape, but like has been said I don't know how much heaving is going to happen?

I had thought about first just trying to drive a metal rod into the ground as sort of a pre inspection as it is not hard to fiqure where the poles would be?

 

[lametec]

My 24' x 24' garage is on a floating slab, not heated, and no issues with heaving.

Might be the soil conditions that allow it. I bought the house in '98 with the garage already in place, so I wasn't around for that discussion.

 

[mooseracing]

Do you know how many tree stumps are in there? Sooner or later they will decompose and create settling.

I wouldn't want to build my building here if I knew that was below it. I rent a dozer and clean the area first and re-fill. Concrete is too expensive to have the pad crack and separate some down the road.

 

[Cougar]

The problem with that is that the OP is in Michigan and has to worry about frost heave. My brother's got a small old horse barn in Northern NY that was built how youre describing, and at some point in time the ground heaved several inches, broke the concrete, and pitched the walls outward onto the ground. Its still standing, but barely. Personally, Id be amazed if even in TN you could leave the heat off for more than a week or two in a shop built like that and not have major issues. Granted, heating the shop will help or cure those problems, but everybody goes on vacation once in awhile.

It doesn't matter that he is in Michigan, Wisconsin, Minnesota or anywhere there is frost. If built correctly there won't be a problem and it doesn't have to be heated. Mine has been up 10 years with no problems.
But I would be concerned about what is buried on his building site, that could be a problem.

Whoever built your brother's place must have done something wrong.

 

[WNYflyer]

Typically you shouldn't be building over top of that "un-controlled" (i.e. everything and anything and not compacted) fill especially that which contains material that can decompose over time and leave voids.

You maybe able to excavate out the "un-controlled" fill and replace with proper backfill/compacted material. Only you can decide if that is worth it. Of course there are ways to construct the foundations while leaving the un-controlled fill in place but those would be unreasonable for most any homeowner type structure.

As for frost heave/protection well: (per Frost-Protected Foundation Design Guide)

Frost heave can only occur when all of the following three conditions are present:

1) the soil is frost susceptible (large silt fraction)

2) sufficient moisture is available (soil is above approximately 80 percent saturation)

3) sub-freezing temperatures are penetrating the
soil.

As can be seen frost problems are highly dependant on the type of soil present as well as drainage. In my area with much clay and freezing temperatures frost heave can be a real issue. The clay holds water and also does not drain well thus more susceptable to freezing/frost heave.

 

[nehog]

Build a metal building on a floating slab. That is what mine is, and it worked out very well.

 

[cyamaha2007]

Even if he builds on top of a floating slab when the ground settles it will create voids under the slab and cause it to settle crack and become un stable. Ive seen 10in of air gab below floating slabs.

 

[joe_padavano]

... Yes, just laid down wood and built on top of the wood. I never saw this before.

There MIGHT be a reason for that...

 

[joe_padavano]

The whole point of a pole building is that by embedding the poles in the ground, you get moment carrying capability, in addition to being below the frost line. I agree with the prior post - have a separate contract to drill the holes first, or do it yourself. One option if you hit chunks of concrete and rocks is to rent a jackhammer and break them up.

 

[Engineer61]

I agree with separating the hole making from the rest of the contract, you may end up digging those holes instead of drilling them, it all depends on what you find under the surface for each one. And also plan on what ever you do for a floor (dirt, concrete, brick etc) to have to empty the building out every twenty years and re-grade and rebuild the floor because you will get holes developing due to settling and sub-surface organics rotting away.

 

[9GUY9]

I would have a hard time believing there is much left of a stump burred 25 years ago. I wouldn't be too worried about settling still going on. Like others have said find out where the post will be and drill them your self.

 

[Diesel Dan]

Talk with the building inspector about the fill. After X amount of years it my be considered compacted. I watched them fill an entire lot with several feet of fill over MANY years in Midland, MI and then put a house on it. It might be worth asking about slab construction to avoid disturbing the sub-soil. Lay down a level pad sight with 1' of clean sand for drainage, grade back with clean topsoil and build away.

I built a 32x48x10 about 10 miles north of Auburn in the early '00s. Had Hoffman builders set the poles and we did the rest.

 

[cyamaha2007]

Get a soil compaction test done. This will determine if you can build where you want. Junk in the holes is a pain but workable. Soil below a certain compaction isnt.

 

[LutzTD]

seems like even if you get the posts in clean holes what about the slab you will end up putting in later? What about getting them or whoever digs the post holes to pop a couple in the field also to determine whats under your future slab? Here in FLA because we are on sand they dig out a foot of sand and add large gravel fill so that the load is spread out, I dont know if that would help but I think I would be hesitant to put such a big investment on a shaky unknown foundation. Maybe some one here knows, but isnt ground penetrating radar pretty mainstream now? Maybe that cost wouldnt be too much for peace of mind?

 

[JasonF]

Thanks for all the ideas guys.
Today I went out and bought a 4' metal rod and used it to just do some preliminary tests by driving it into the ground where the poles would be located. Some of the holes I was able to drive it all the way down, most I could drive it down ~30"s and then I would hit something solid.
I agree with what has been brought up by some of the posters that settling may still occur although it has been at least 25 years. I would be less concerned about settling with it being pole built as structurally there should be little affect, now on a slab any settling can affect the entire structure. I did talk to a local excavator who did think that compaction shouldn't be an issue after this length of time, he suggested just stripping the vegetation and grading with 12" of sand.
I am leaning towards doing the garage in three parts like has been suggested. I could just check with the builder to see what the price would be to do the holes in advance but what to do when he hits something? I also do like the idea of just doing the holes myself and possibly using a jack hammer to bust up any concrete. My last barn I built myself and then I rented a Bobcat with an 18" bit so I know how to do that part. I've never run a jack hammer so I would have to see what thats all about.

 

[Modifieddriver]

Contrary to what was said about 25 years and it's now settled.

It's common practice to dig a hole and bury stumps etc. on a building site. I don't like it and never will.

Twice I've been involved with situations where stuff was buried. In both cases, the problems didn't become a problem until AFTER 25 years. I had to bring in fill dirt to correct the problems. But it had to be filled and refilled over a several year period.

I wouldn't build anything on the site you describe.

 

[nehog]

Contrary to what was said about 25 years and it's now settled.

It's common practice to dig a hole and bury stumps etc. on a building site. I don't like it and never will.

Twice I've been involved with situations where stuff was buried. In both cases, the problems didn't become a problem until AFTER 25 years. I had to bring in fill dirt to correct the problems. But it had to be filled and refilled over a several year period.

I wouldn't build anything on the site you describe.

I have to agree WRT degradable fill (stumps, etc.) For non-degradable fill it has probably settled as much as it ever will.

My next door neighbor, after 25 years still has to fill the stump dump every few years as it slowly settles down. I asked a guy who was doing some work for me, and he immediately said "They were not buried deep enough..."

He then showed me how deep to bury them, and I've not had any of the problems the neighbor has!