New Garage Slab - Concrete Over Stump?

[Don Ro]

Having a new garage built as an attachment onto my existing...
12" - 14" fruit tree stump sitting there. A good idea to back hoe it out or leave.
I would think that no organic material ought to sit under the slab.
Looked on several forums and they all say to remove it.
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Would this even pass inspection?
What say the PPOT gurus?
Thanks.
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PS It appears as though I'm dealing with a flunky contractor.
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[billybek]

I had a big crab apple tree where my garage stands now. Had left about 3 feet or more out of the ground. The bobcat guy got it out of the ground but it was a big rodeo for him to do it. Slab still cracked pretty badly.
If you do dig it out, use crush gravel and sand to fill the hole. Compacts nicely.

[JJ 911SC]

Remove...

https://www.google.ca/search?source=hp&q=tree+stump+under+concrete&oq=tree+stump+under&gs_l=psy-ab.1.0.0l3.2106.11475.0.14033.18.17.1.0.0.0.141.17 36.10j7.17.0.foo%2Cnso-ehuqi%3D1%2Cnso-ehuui%3D1%2Cewh%3D0%2Cnso-mplt%3D2%2Cnso-enksa%3D0%2Cnso-enfk%3D1%2Cnso-usnt%3D1%2Cnso-qnt-npqp%3D0-1701%2Cnso-qnt-npdq%3D0-54%2Cnso-qnt-npt%3D0-1%2Cnso-qnt-ndc%3D300%2Ccspa-dspm-nm-mnp%3D0-05%2Ccspa-dspm-nm-mxp%3D0-125%2Cnso-unt-npqp%3D0-17%2Cnso-unt-npdq%3D0-54%2Cnso-unt-npt%3D0-0602%2Cnso-unt-ndc%3D300%2Ccspa-uipm-nm-mnp%3D0-007525%2Ccspa-uipm-nm-mxp%3D0-052675...0...1.1.64.psy-ab..0.18.1746...0i131k1j0i10k1j0i22i30k1.5SGqTtbq2 Go

[Don Ro]

^^^
Been Googling...thanks.
Any other opinions?

[Mark Henry]

I've built many buildings, traditional, floating, pole barn...I say remove it.
Seeing as you already have it formed I'd do the pour first.


Edit, use 3/8" crush gravel, packs better than sand. I'd also dig it out and put in 12-18" of crush stone and compact, to stop concrete cracking a substantial base is very important.

[stomachmonkey]

I'm no expert but I'll assume at some point in the future that organic material will break down leaving a cavity.

Isn't that how sink holes start?

[Don Ro]

Originally Posted by Mark Henry

I've built many buildings, traditional, floating, pole barn...I say remove it.
Seeing as you already have it formed I'd do the pour first.

So pour the footings first?
Then remove the stump? Back fill, compact, then pour slab?

[KOH]

I say remove.

I had several trees taken out of my backyard 10 or so years ago, the stumps ground down, and the whole yard bulldozed flat. I now have craters where each of the trees once stood.

[asphaltgambler]

Looks like there has been a fair amount of money and time invested so far.....................take the extra time and remove all of it. At one time it was a living thing and you can't be certain it is completely dead.

Last thing you'd want is a foundation issue later on................................

[GH85Carrera]

Remove it.

It will eventually rot, and the ground collapses at that spot. I have worked with a lot of historical aerial imagery and done the research of peoples houses with foundation problems. Many low life developers would buy a farmers land and put in a development. Every farmer has a trash pile and sometime several generations of junk. Old water heaters, bathtubs and tree stumps. The developer just puts a layer of dirt on top and builds a house. For the first few years all is fine but 25 or 50 years later the house is sinking. We would print an aerial from 1951 and see the farmers trash dump right where someone's house is now. We did one where a lady's house was right over a large oak tree, she was spending a small fortune to fix the foundation.

Of course the worst is old oil and gas wells that were not properly sealed. One couple had the kitchen sink explode when they hit the garbage disposal switch because an gas well was right under the kitchen. Natural gas has not odor at all and they could have died easily.

It will be a pain to get it out, but you will be happy you did in a few years.

[scottmandue]

One word... EXPLOSIVES!
J/K
Already been said but seems like stump will rot and leave a void under the slab eventually.

[Don Ro]

4" of concrete to be poured over the stump. How about rebar the snot out of the top of the stump after it's either ground down or back hoe'd out?

[Indescikov]

Termite bait.
Remove

[Neilk]

We had the sod replaced in the front yard of our old house. They leveled the soil prior to doing so, but after a couple of years, there was a nice sized indentation in one spot. I was recently looking at pictures of the house online and saw a picture from around 2004 and sure enough, there was a big oak tree there. I guess the previous owners only did the bare minimum to remove the stump and the soil keeps compacting.

So one more vote for removing.

[MBAtarga]

Rent a stump grinder or pay for a service to grind down the top ft or so of the stump and roots. Remove the organic debris and replace with tamped soil/sand - whatever is native.

Also - isn't that planned to be a monolithic pour? looks like it to me.

[Don Ro]

Just spoke w/code inspector...code says no vegetation...Period!
Now just need to find out how deep to grind.
What a whore's nightmare with this contractor.

[Mark Henry]

Figured that...and take my advice on the base prep, it makes or breaks a good floor.

[Don Ro]

Another call to the inspector...no grinding, the stump MUST be removed.
Good to know.
Thanks gents.

[Neilk]

Originally Posted by Don Ro

Just spoke w/code inspector...code says no vegetation...Period!
Now just need to find out how deep to grind.
What a whore's nightmare with this contractor.

I assume you would be on the hook for removing the stump, but is the contractor going to bill you to redo the work?

Hopefully that will be the only shortcut the contractor tries to pull on you. Wasn't there a thread recently about over zealous code inspectors? Looks like this one saved you from a future headache (in this case).

Good luck!

[Don Ro]

Not my expense re: the stump. There were 4 of them that the contractor saw prior to contract.
I guess they successfully dug out the other three.
But they've been poo pooing the stump removal/grinding all along. I'm not impressed with this crowd.
Some major deceit/lying going on all along.
But I'm watching them.
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Monolithic pour - Do you mean everything poured all at once?