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How deep should the footers be?

imjustdave

Well-known member
Joined
Apr 9, 2014
Messages
204
Location
Sumner WA
ard- They said the weight of the Bobcat and mini-ex did compact the soil. They also added the 6 sonotubes and rebar. I had a soil engineer on-site today who took core samples down to 6 feet.

Excavator is on tracks and has less PSI then you walking on it, yes the entire mass helps but its not like a compactor. Also your dirt is ... unknown as of yet.

Glad you have an soil engineer taking a look.

I agree with LLWillysfan on the sono tubes, I never used such a thing in 5+ years of concrete work, thicken edges, 6" slab, lots of rebar, pier pads ETC but never once did we buy sonotube to go down to undisturbed soil... we dug to it and had the footer there. In your example I don't recall an engineer designing a monolithic pour like this, it would be upside down T footer, then fill on the outside wall side and engineered backfill to make level than floor installed. Footer supports the building and the engineered fill supports the car inside.

Also how big are these sono tubes? Any rebar? Is there going to be a beam or something resting on top in this area? are they on the perimeter or somewhere in the center of the floor?


Bob15- after discussion with the contractor and the concrete company I am getting 3,000psi concrete

What does your lift need? and or call out for.

:bowdown:
Overall I'm glad you have called out the builder and having things looked at. The thing that I don't understand is someone who sees plans every day won't use that info on a job without plans, yeah I get sometimes they are overbearing but it's the foundation of the building as a contractor you need to try and do right by the customer, VS save every penny you can on shortcuts.
:shocking:

After a year or 2 I pretty much knew what the engineer wanted to see, the few exceptions were Fire Station floor, hotel elevator shaft, and the pool. Made it really easy to bida, install, and pass inspection with ETC, it wasn't rocket science to mars and back where it was all theoretical science. :lol_hitti
 
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bob15

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Joined
Dec 8, 2011
Messages
6,863
Location
Northeasten, CT
An excavator isn't going to compact the soil enough. The reason they make wide and long tracks equipment (or even farm tractors with duals and triple tires) is to reduce compaction. You need a vibrating compactor in there. If not, the ground under the slab can settle and leave a hollow void under the slab. And what happens if the void is under your lift?

Going with 3k concrete limits your lift buying choices. If the concrete guy cannot work with 4k concrete, maybe you need a different contractor or they use a different batch plant. Or get an opinion from another concrete/foundation person (or even ask the building inspector). Why start off behind the eight-ball with low psi concrete?

Do you really trust this contractor to build the building? He already tried to skip code with the footings. What makes you think he will be different with the rest of the construction? Where did the builder get the plans from? Are they from an architect or is it something he just put together? The buildings you have seen from him, how old are they?

Good luck......
 
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VM Builders

Member
Joined
Mar 5, 2020
Messages
18
Location
Arizona
Ask him to see the plans.
Ask him if they have been stamped by an engineer.
Ask him if there was any geo technical report done.
If the plans were approved by the local building department and you have a structural and soil engineer involved it should be ok. There are foundations that don't even have footings (Post-tension slab) but I don't think that is what you have.

If you have any questions feel free to contact us.
 
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MotorCityBear

Active member
Joined
Sep 24, 2012
Messages
31
Location
Blairsville, GA
Yes the pour was completed. The footers were dug deeper and wider with additional rebar, per the building inspector. From what I can tell at this point, it looks good. Framing begins on Monday.

The engineered plans appear to be for the building, trusses, floor joists etc. I did not see anything for the foundation but I did get a soil engineer to test the soil after the initial issue.

I tried to post a pic of the plans but I must be doing something wrong as it is always too large.

VM Builders, thank you for your offer to contact you with questions.
 
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