Pin Foundations
Pin Foundations
(OP)
I'm considering spec'ing this foundation system for a house:
http://www.pinfoundations.com/html/ink_d...
The diamond piers cost only $165 each and 25 mins. labor. The load rating is 8600 lbs per pier, with 2000lbs uplift, for the soil conditions. This is so cheap and quick, it's very tempting to forget about building a basement. Combined with a floor made from a 12" SIP, It eliminates so many of the challenges that basements and crawlspaces have. I think I can reliably freeze protect the incoming water pipe
Does anyone see any potential problems?
http://www.pinfoundations.com/html/ink_d...
The diamond piers cost only $165 each and 25 mins. labor. The load rating is 8600 lbs per pier, with 2000lbs uplift, for the soil conditions. This is so cheap and quick, it's very tempting to forget about building a basement. Combined with a floor made from a 12" SIP, It eliminates so many of the challenges that basements and crawlspaces have. I think I can reliably freeze protect the incoming water pipe
Does anyone see any potential problems?





RE: Pin Foundations
RE: Pin Foundations
Be careful! Portions of the Denver area (I'm guessing from your 'handle') have severe problems with expansive clay shales. Consult with a qualified geotechnical engineer before you start using a shallow foundation system, no matter how cheap -
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Pin Foundations
At any rate, it's a good point, and I'll check with the supplier.
RE: Pin Foundations
D. Bruce Nothdurft, MSCE, PE, PG, M.ASCE, etc, etc,...
Principal Engineer/Geologist
Atlantic Geoscience & Engineering
Charlotte, NC
RE: Pin Foundations
These soils when left undisturbed, don't actually move, they just expand and contract proportionally to the moisture content. The volumetric changes cause the soil pressures to change.
Hmmm,
What makes you think that soils can expand and contract without actually moving?! Yes, they do exert pressure - if there is something impeding the soil's movement. But they do move. And try to imagine expansive soil movements that can be measured in feet...
Expansive soils/shales will push your little pin foundations around just like any other shallow foundation - since the swell pressures are often measured in tons per square foot.
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Pin Foundations
RE: Pin Foundations
And I continue to wonder:
If it's 1/2 inch wide at 22 feet, where's the bottom of the crack?
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Pin Foundations
RE: Pin Foundations
Helical piers? Not strong enough - the steel shafts would be pulled in two. And you couldn't get them deep enough to be useful since the undrained shear strengths get pretty high with depth (8 ksf+.) We typically use drilled and underreamed piers, with 2% - or more - reinforcing steel. And we try to keep the pier shafts as small as possible to avoid the uplift problem.
Needless to say, we don't typically design for bearing capacity...
Please see FAQ731-376 by VPL for tips on how to make the best use of Eng-Tips Fora.
RE: Pin Foundations