building with untreated posts

Discussion in 'Homeowner Helper Forum' started by hazazil, Jul 31, 2018.

  1. hazazil

    hazazil New Member

    Jul 18, 2018
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    Northern Michigan
    Just curious..........

    So I purchased 6 roofing panels from someone who was moving. I had to use a crane truck to load/unload them on a car hauler trailer. Each panel I was told weighs 500 pounds or so. They are approximately 8 feet by 11 feet.

    I was hoping to place them 3 long and butt 3 of them together so the total dimensions would be 24 feet x 22 feet.

    Obviously that's alot of weight to hold up. I have some dead standing ash trees that I could take down and make some big posts. I figured I could even make some huge posts up to 24 inches for where the 2 panels but up together if needed. I've been reading online about using untreated posts for post frame buildings.

    Some say treat the part that will in in the ground with tar or tar/kerosene. Others say put in a concrete pier/pillar and attach post to top of concrete pier(which defeats the purpose of pole building and jeopardizes lateral support)

    Was just wondering what your thoughts are and if anyone has done anything like I'm wanting to do. Obviously I do not want to go to the store and buy any lumber. I do have some cedar trees on the property but don't want to cut them down just to use them as posts.

    Thanks for the advice.
  2. Ikeholt

    Ikeholt ArboristSite Operative

    Feb 6, 2008
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    If you have Ash and Cedar, there's probably Black locust growing somewhere in your neighborhood. Ask around, shouldn't cost you much. Locust poles will last forever. Old utility poles are occasionally available also.
  3. old CB

    old CB ArboristSite Operative

    Jul 4, 2011
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    front range rockies, Colorado
    I'm pretty sure that ash would deteriorate pretty quickly in contact with soil. I once had a neighbor who built a teepee-style structure using sugar maple poles. Nice place, kinda--but the poles turned to compost in no time.

    Cedar would be your choice. Even then you want to prepare the poles. Skin them, remove the bark with a drawknife, if you want them to last. Or black locust. (Or treated utility poles.)

    But ash won't last if you plant it in the ground.
  4. ChoppyChoppy

    ChoppyChoppy Addicted to ArboristSite

    Jun 17, 2013
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    ~3000lbs isn't that heavy.

    I'd pour a concrete pad and bolt the post to it vs putting it in the ground. Not much more work or cost.
  5. JeffGu

    JeffGu Antagonist/Heckler

    Nov 16, 2014
    Likes Received:
    Osceola, Nebraska
    That's a 5.6 lbs. per square foot static load... how much do you think an asphalt shingle roof weighs? You're not putting a parking garage up, are you?
    Canyon Angler likes this.
  6. Marine5068

    Marine5068 Addicted to ArboristSite

    Nov 20, 2009
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    Madoc, Ontario, Canada
    So are you building a gable roof with them ? 3 on one slope and 3 on the other making them into a gable roof plane?
    Northern Michigan is a good snow load so you'll need to secure them to a ridge beam as well as have other beams frame all around the top of that post layout structure.
    If that's your plan then you will also need to tie the one side to the other with collar ties to keep them from pushing out on the posts and collapsing(basically you're making a triangle).
    Posts (or columns as we call them in Architectural Design) have no lateral support, only beams can do that job.
    Take some pics or draw up a design you have in mind and I'll take a look at it and give you dome possibly ideas of what can be safely built.
    The only other thing I might add is that you may have a hard time getting your building permit if you use unstandardized materials that don't conform to the building code.
    Good luck and let's see the pics.
    jefflovstrom likes this.
  7. ArtB

    ArtB ArboristSite Operative

    Apr 7, 2003
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    renton wa
    How long do yu want the structure to last?

    Except for black locust as mentioned, unless you use pressure treated ground contact rated lumber you will limit your building lifetime to something like 10 years.
    I did soak DFir in dreosote for 2 months once and it has lasted a few decade

    Even PT creosote RR ties often have the centers rot out after a few decades.

    Our poco gives away pole butts, have split those for fence posts, they rotted off after 30 years once split.

    I do have some PT creosoete piling buts that have been in the ground since 1980 that have no rot, but those are REALLT heavily PT

    Raw log of ash even with a brush coat of the weak consumer preservatives available to today may last 6 or 7 years.

    And, just for kicks, 8 years ago laid 2 32 in dia cottonwood logs on the surface for a shed 'foundation'. The roof of that shed is now 30" lower <G>

    Pour a concrete pad, 6" or more above ground surface, Keep dry. install an aluminum or copper termite shield between post bottom and concrete, AND treat the bottom of your ost by soaking in a bucket of preservative for a few day.
  8. Canyon Angler

    Canyon Angler Addicted to ArboristSite

    Aug 18, 2006
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    Far East Virginia
    How does this "defeat the purpose of pole building"?

    As for lateral support, put a piece of 3/4" rebar into your concrete pier and drill a 3/4" hole into the bottom of your post. Voila: Lateral support to the tune of > 25ksi.

    Do you think it's going to last longer or be laterally stronger if you sink the wood post into the mud?

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