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jonmartinson
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# Posted: 24 Aug 2020 03:39pm
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we started a new build of a small 12x24 cabin in northern mn. we used pylex screws for the footing with very mixed results....we had a lot more rock to deal with than we thought we would, so not all of the 20 piles are set as they should be (we were shooting for 42"+ in depth...anyway the foundation is very unstable at this point and i am wondering if adding cribbing would be a viable solution to sure up the structure or do i need to trash the project and start over from the ground up? Note the footprint has been framed out at this point...we thought doing so would have "tightened-up" the footing, etc.
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Brettny
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# Posted: 24 Aug 2020 03:53pm
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20 piles for a 12x24 and it's still wobbles? Adding wood isnt going to tighten up a poor footing. Placing cribbing under it is just basically putting your cabin on blocks.
Is this what you used? Can you post pictures of what you currently have and how it's all setup?
https://www.ebay.com/i/333197768168?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0 &mkcid=2&itemid=333197768168&targetid=935431405413&device=m&mktype=pla&googleloc=9004 848&poi=&campaignid=10455986818&mkgroupid=104612009500&rlsatarget=pla-935431405413&ab cId=2146002&merchantid=101650985&gclid=EAIaIQobChMIs7nL5M606wIVArbICh2rXwkUEAQYAiABEg LL0vD_BwE
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jonmartinson
Member
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# Posted: 24 Aug 2020 04:06pm
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I'm sorry it wasn't 20, it was 17. Yes, that is the he product we used.
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snobdds
Member
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# Posted: 24 Aug 2020 05:03pm - Edited by: snobdds
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Is it racking side to side or are the pilings moving up and down?
Those pylons have no racking strength, only compressive strength. You need to add the racking strength. You will need to add bracing that goes from the pylon to the rim joist in criss cross fashion like you started doing. You might also need to tie and weld a bar from pylon to pylon to prevent side loading.
I don't think you need to tear it down, you just need to add racking strength to your floor.
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jonmartinson
Member
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# Posted: 24 Aug 2020 05:07pm
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Thanks.
Yeah nothing is moving up in down, very solid that way. The structure as a whole (and a number of the pylons individually) wiggle laterally in all directions.
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snobdds
Member
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# Posted: 24 Aug 2020 05:15pm
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Need something along these lines
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snobdds
Member
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# Posted: 24 Aug 2020 05:20pm
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It's not going to be easy because all your pylon heights are different, but it's needed before building the walls, otherwise all your measurements will move around.
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jonmartinson
Member
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# Posted: 24 Aug 2020 05:35pm
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So it seems like I need to secure each plyon right at ground level, does that change anything?
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Bruces
Member
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# Posted: 24 Aug 2020 06:27pm
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It’s a leverage thing ,so the closer to the ground you can get a brace the more rigid it will become .I myself would figure out a metal brace system ,look at pole dock hardware,they have the same problem with the jiggles and there is kits to brace the legs ,you can use there kits or fabricate your own if you are capable .
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jonmartinson
Member
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# Posted: 24 Aug 2020 06:39pm
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I'll look into that, thanks!
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jonmartinson
Member
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# Posted: 24 Aug 2020 07:13pm
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What about pouring concrete around each post?
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ICC
Member
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# Posted: 24 Aug 2020 07:32pm
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The manufacturer installation info directs that the pylex are to be screwed down, and hammered, until they are about 6 inches above grade. I know you said you couldn't get them, or some in any further. That is the source of the problem with the wobbles though.
Building a shear wall at each corner would be the strurdiest correction.
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jonmartinson
Member
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# Posted: 24 Aug 2020 08:26pm
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Yeah we screwed and hammered on all of them, some with perfect results. I will look into the shear wall option, thanks.
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Popeye
Member
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# Posted: 24 Aug 2020 10:56pm
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U-bolts would make it easy to attach the cross bracing to the 1.25" pipe.
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Brettny
Member
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# Posted: 25 Aug 2020 07:17am
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Angle braces are needed to stop it moving in that way. Notch the braces for the wood your connecting to. Use through bolts or something like a SPAX structural screw.
Your metal posts are out of the ground quite a bit on some of them so its leverage will not be in your favor. If you can weld you can you angle iron welded to the metal posts and bolted to the wood. Attaching as close to the ground as you can makes the brases do more.
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jonmartinson
Member
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# Posted: 25 Aug 2020 09:52am
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Any thoughts on using the pylex stabilizers may in addition to some sort of cross bracing?
Or am I too high out of the ground on some of these?
https://pylex.com/en/products/10575-pylex-lateral-stabilizer
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ICC
Member
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# Posted: 25 Aug 2020 02:49pm
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I can't see those helping your situation much. Isn't the unstableness occuring in the length of pier that is above ground? If so the section that is above ground needs to be made resistant to all lateral motion.
If you can weld that could be a good solution. But welding onto the metal piers might very well void any warranty.
I have seen a pile system that was used in a mountainous area in NM here that was cursed with unstable soil, but in a beautiful spot. The engineered solution was to have many piers installed at angles to brace the structure. They were installed with a HD hydraulic driven machine and quite deep.
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jonmartinson
Member
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# Posted: 25 Aug 2020 03:47pm
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It's hard to say the the exposed length is the entire issue. I noticed that even the screws the we were able to get to that 6 inch exposed above ground have movement to them right at ground level as much as the others....
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NorthRick
Member
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# Posted: 25 Aug 2020 04:08pm
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You need to do something along the lines of this:
https://www.tmpalaska.com/our-system/lateral-stability/
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jonmartinson
Member
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# Posted: 25 Aug 2020 04:58pm
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Thank you to everyone. All of this input has been a big help!
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Brettny
Member
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# Posted: 25 Aug 2020 05:07pm
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Are these even rated to hold up a building?
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jonmartinson
Member
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# Posted: 25 Aug 2020 06:14pm
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Excellent question.
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jonmartinson
Member
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# Posted: 25 Aug 2020 06:15pm
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Either way I'm kind of past the point of no return on that.
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Brettny
Member
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# Posted: 26 Aug 2020 05:53am
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Your def not past the point of no return. You would only need to remove a few boards at s time to put sono tubes under the joists. Build a poor foundation and it wont matter how nice the cabin is.
There was a member on here asking about how to repair a poor foundation. Some time later he went back and it was all on the ground.
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jonmartinson
Member
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# Posted: 26 Aug 2020 09:52am
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Yeah we have been thinking about adding concrete footings too....not necessarily as a replacement to the ground screws, but in addition to add to the stability?
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Brettny
Member
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# Posted: 26 Aug 2020 11:38am
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Sono tubes would be a replacement to the metal posts. Those metal posts dont really have any lateral stability because there only 2in wide at the most.
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snobdds
Member
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# Posted: 26 Aug 2020 02:41pm
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I would be calling who ever installed the screws and ask how they stabilize the things. Every single manufacturer of those screw pylons have their own way of making them stable.
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jonmartinson
Member
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# Posted: 26 Aug 2020 02:43pm
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That's the thing, I installed them.
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NorthwoodsGuy
Member
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# Posted: 31 Aug 2020 12:16am
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Jon- When you say Northern Minnesota, whearabouts do you mean? Are you on the shore or the range? What is topsoil to shelf rock like?
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jonmartinson
Member
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# Posted: 31 Aug 2020 08:24am
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I'm not that far north. Carlton County about an hour south of Duluth. As far as I have seen, and have been told in our immediate area, we are on clay and some sand. A lot of large rock/boulders. I'm between a couple creeks, a mash and big, so we have fairly wet conditions too.
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