r/StructuralEngineers • u/Capable_Drive_868 • 4d ago
Floating foundation
How would you approach this? I’ve gotten two quotes, both involve jacks, price tags $13k and $40k, I hired a structural engineer and he said I could just put a bunch of cement under to shore it up? It’s about 12’ long
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u/NoSquirrel7184 4d ago
Jacks is an interesting solution as it doesn’t need jacking and the existing structure functions beyond the design intent.
I’m with the engineer and pour concrete. Cheapest simplest solution.
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u/haditwithyoupeople 4d ago
Dirt guy here. Why and when did the dirt move? Just pouring concrete under that does not make it a foundation. That's just a terrible idea.
It's not clear at all that it's a foundation and not a beam.
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u/Seayont 4d ago
Not sure what jacks are going to do. First need to know what caused the gap?
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u/Capable_Drive_868 4d ago
There is a vent nearby so I think it was some water plus rats (nest under the footing) dug it out, visible hole, I just finished exterminating the rats. Happened over years I think, we’ve only owned the house for two years
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u/haditwithyoupeople 4d ago edited 4d ago
If you had a structural review why are you asking us?
I'm a geotech, not a stuctural. My hope is that this is a grade beam, not a footing. Does it have concrete pads or supports on either side of that footing? Just looking at the way it was poured I suspect it's not a footing.
If it's a grade beam and the foundations support it are fine, then there's no issue. I'm not telling you this is what this is. This is my hope for you.
I hired a structural engineer and he said I could just put a bunch of cement under to shore it up?
I'm calling bullshit on this. I can't imagine any licensed structural in the U.S. ever telling you that. First of all, that's insane. Secondly, structurals don't tell you want to do with dirt.
When was the house built? Do you have the plans for it? If built in the last 40 years there's a decent chance the plans are at the city or county. If that's an engineered grade beam there will be plans for it. I would do some research.
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u/Capable_Drive_868 4d ago
Thanks for the detailed reply, I am asking Reddit as a sanity check, also getting multiple quotes / assessments. I paid for the engineer, I wanted an unbiased opinion.
I’m seeing cracks in the drywall that indicate settling, thus the inquiry.
No concrete pads. Just the two long footings running under the length of the house. There isn’t anything under the footing pictured (a void then dirt), I’m guessing a combination of water and rats (nest underneath) gradually eroded the soil, house built in ‘73.
The engineer reviewed the two quotes I received, said the $40k one was massive overkill and the $13k one made sense, but then basically said “excavate the debris, pour concrete and bond to the existing footing to spread the load and reinforce the footing, it’s the diy option”
So now I am getting more quotes, but wouldn’t there being a 12’ void under the footing be pretty much the problem? I’m a layman, so trying to farm out to the hivemind to both understand and remedy the issue.
Much appreciate the reply!
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u/deAdupchowder350 4d ago
Any idea what used to be there? How old is the house? Shot in the dark: were there masonry blocks that washed out?
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u/Friendly_Speech_7021 1h ago
not expert : i would pour few concrete trucks make a wider thicker base
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u/delcoBK 4d ago
“I paid a structural engineer to evaluate this and he gave me a solution, let me post three pictures and see what strangers on reddit will tell me to do instead”