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Thread: Post foundation issue

  1. #1

    Default Post foundation issue

    A friend and I started working on the foundation for my shop/cabin out in Petersville this past Wednesday and Thursday. We actually made good progress and were able to hand dig 8 of the needed 9 holes for the rail road tie posts then ran into a problem with #9.

    We hit a giant rock about 6-8" below the surface and it turned out this thing was enormous, 6'x6'x2'. I'm looking for some suggestions on what would be my best options to finish the foundation.


    As an FYI, there is no permafrost and we were able to get the holes down to about 3 feet before we hit what looks like gray fine and coarse gravel and we dug down to 4 feet overall.

    Here's a couple of pics, my buddy is standing on the rock in the first pic.


  2. #2
    Member Gerberman's Avatar
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    What I did is drill some holes in the rock, put in some adhesive anchors mount a steel plate and bolted the column to the plate, I had put ears on the plate so it was just like a factory build column bracket. Lots of footing.

  3. #3

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    Thanks for the info gerberman but I think I may try and remove it using a hammer drill and Ecobust.

  4. #4

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    Use dynamite and blow it out of there! Just kidding. If all else fails, build a concrete footer on top of it with your post cemented directly into the footer. Fill in with dirt all around it and call it good. Correct me if I'm wrong but it appears from your picture that the post with the rock is not on one of your corner footings right? If it is just a support in between two corner posts then the shear strength might not be as crucial. A post spanning the middle would just be there to support the span of the beam.

  5. #5
    Supporting Member iofthetaiga's Avatar
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    Quote Originally Posted by Gerberman View Post
    What I did is drill some holes in the rock, put in some adhesive anchors mount a steel plate and bolted the column to the plate, I had put ears on the plate so it was just like a factory build column bracket. Lots of footing.
    +1 It would be the best of the 9. Tho better than wood would be to anchor a piece of rebar into it and pour a concrete pier on top.
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    Default Post foundation issue

    I wouldn't try and remove it or break it. Maybe get a few bags of ready mix and pour around the edges that you disturbed but that is more of a post that anything you could put in with a 6x6 or a Bigfoot at the base of a sonotube. Maybe put a Bigfoot on top of it, level it and fill with concrete with a 6" anchor for a post. Lots of things you can do. But that is solid, leave it there and take advantage.
    I would drill a few pieces of rebar into it though to keep it from sliding.


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  7. #7
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    Yep- I would leave it there: excellent support. You might consider incorporating the ability to adjust column height. It will move differently than your posts.

  8. #8
    Member DRIFTER_016's Avatar
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    I pinned my posts into solid granite using saddles.
    Drilled a 1" hole into the rock, blew out the dust and filled the hole with non-shrink grout before setting my saddle in.
    My cabin sits on twelve of these things.






  9. #9

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    Quote Originally Posted by DRIFTER_016 View Post
    I pinned my posts into solid granite using saddles.
    Drilled a 1" hole into the rock, blew out the dust and filled the hole with non-shrink grout before setting my saddle in.
    My cabin sits on twelve of these things.





    That's Awesome Drifter!!! Put's a whole new meaning into the saying the wise man built his house upon the Rock! That place looks solid (no pun intended)! That place will never move an inch. Not even in an earthquake!

  10. #10
    Member DRIFTER_016's Avatar
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    Quote Originally Posted by Bushwhack Jack View Post
    That's Awesome Drifter!!! Put's a whole new meaning into the saying the wise man built his house upon the Rock! That place looks solid (no pun intended)! That place will never move an inch. Not even in an earthquake!
    Good thing is we don't have them shakers over here.
    Just the odd gigantic forest fire.


    Luckily my landlord has a bunch of Hardy Board I can have cheap that will cover the back wall and the level below the floor.
    Roof will be metal and I'm plumbing a fire fighting system that will run off a high pressure pump down @ the lake.



    I have built it with a good bit of dry storage underneath that I can use to store sleds etc.


  11. #11
    Member oakman's Avatar
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    I like the TNT suggestion! Make sure to get it on video to share with the rest of us.

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    Quote Originally Posted by oakman View Post
    I like the TNT suggestion! Make sure to get it on video to share with the rest of us.
    Ya! there's no problem can't be fixed by the application of a small amount of explosives...

  13. #13
    Member DRIFTER_016's Avatar
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    If yer gonna blow stuff up, do it right!!!
    Call in a squadron of F-16's to take care of the offending rock!!!!

  14. #14
    Member Music Man's Avatar
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    Quote Originally Posted by DRIFTER_016 View Post
    If yer gonna blow stuff up, do it right!!!
    Call in a squadron of F-16's to take care of the offending rock!!!!

    No! It is more fun to do it your self!
    When seconds count, the cops are just minutes away.
    '08 24' HCM Granite HD "River Dog"

  15. #15
    Premium Member kasilofchrisn's Avatar
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    Quote Originally Posted by Music Man View Post
    No! It is more fun to do it your self!
    And cheaper.
    Last I checked F16's weren't cheap to rent. Especially fully loaded.
    But on the other hand black powder is relatively easy and inexpensive to make and use with locally available chemicals from the local feed store.
    "The closer I get to nature the farther I am from idiots"

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  17. #17
    Member Music Man's Avatar
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    A10's would be quieter.
    When seconds count, the cops are just minutes away.
    '08 24' HCM Granite HD "River Dog"

  18. #18
    Member DRIFTER_016's Avatar
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    Quote Originally Posted by Music Man View Post
    A10's would be quieter.
    Heaven forbid we alert the rock to it's imminent demise!!!!

  19. #19

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    Dang, I had forgot about this thread, appreciated he feedback too..

    This is what I ended up doing. We placed a railroads tie on each end of the rock then ran another across the top of them. It worked out great. We've got the floor on and will be putting up walls and hopefully a roof this week.






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  20. #20

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    Was there a reason that you did not put a rim joist on your floor joist?

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