Pole barn posts

[john300exc]

I am in the process of building a pole barn, 40 x 80 with a 15-20 foot lean to on one side. Foundation dirt work is almost done. My plan is/was to sink 6x6 posts into the ground, use metal trusses connected with 2x6 purlins and girts. A 5�or 6�concrete floor will be poured after the roof is on but before the walls are finished.
I had assumed the poles should be surrounded by concrete, but I have found conflicting advise on placing the poles in concrete. A lot of the information I can find on the web concerns wood treated with CCA or older wood treatment systems.
The only treated 6x6 posts I can locate in my area are ACQ treated (.40) and I am uncertain as to the treatment level needed for ground or concrete contact, .40 vs .60.
Can I expect the ACQ treated post to last as long as CCA posts, and will placing the posts in concrete do more harm than good. The roof will have about a 2 foot overhang and the foundation area has an adequate slope away from it.
The ACQ preservative is also more corrosive than CCA and there have been problems with fasteners that were originally specified for use.
Has anyone who has used ACQ treated wood experienced problems with fasteners?

Sorry for the numerous questions, I am obviously a newbie at this. The project is destined to be “do it yourself� as I am retired and have more time on my hands than money in my pocket. I have adequate labor for the job but we have no actual experience in pole barn construction.

[beenthere]

I wouldn't put them in concrete, and I would use stainless steel fasteners.
I'd make sure the footing under the posts is substantial concrete on solid ground, and not on backfill. I'd tamp gravel around the posts after the superstructure is up and aligned (chance for final re-positioning if needed) and will help the posts fight decay. I'd pour concrete up to the posts with a spacer between the wood and the concrete for movement.

Not sure why metal trusses? They fail quickly in a fire of even small size.

[Pat]

I have been watching a church being constructed along the lines of a pole barn. The "poles" had overshoes! There were plastic covers on the bottoms of the 4x4 or 6x6 (I didn't go onto the building site, just drove by about 10 times a week.)

The plastic covers extended well above the ground and ended up on the inside of the building where it is unlikely there would be a way for moisture to get inside the "booties."

I have no idea where those posts were purchased. I think they may have come with the plastic covers but am not entirely certain. Anyway it looked like a good idea as the wood would be out of contact with soil moisture and organisms.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[beenthere]

If the wood posts have moisture in them, then the bottoms of the posts will not dry because the water is trapped.

In the 60's, a large building was constructed with laminated southern yellow pine beams and posts. These were huge, like 12" thick by 4' deep at the 'post' bottom that sat in a steel 'cup'. These were likely made from kiln dried syp, but over the first few years, water drained out of those laminated beams to the point the steel cups had to be drilled for drainage. Pretty amazing. These posts were probably 4 stories to the top.

I'd think the same thing might happen with concrete-entrapped posts or plastic wrapped posts. I believe the utility industry tried things like this years back, to wrap their posts in plastic, but they also added preservatives to fend off rot. They don't do it anymore, so apparently it didn't work out.

Locally, in our village park, huge treated utility poles were erected to hold ball-park lights. They were concreted into the ground. One only lasted 7 years, and when it fell, it surprised (and scared) a lot of people. I was on site and could walk around with a screwdriver and push through the 1" shell layer that was not rotted away. All the poles were decayed on the inside, and only the treated shell remained intact.

[Pat]

beenthere, There is a common thread in all the failures you mention, a fair source of water. If the plastic encapsulated (on the botom) posts have their tops in a dry environment, then wouldn't the moisture be likely to distribute itself relatively equally along the post and be a functon of the average relative humidity in the building?

I don't know what if any preservatives may have been introduced in/under the plastic boots.

On sailboats, masts stepped on deck historically have been stepped in tabernacles which don't always drain as well as they should which results in a good chance of rot at the base of the mast. (Wood mast)

I helped a friend/neighbor treat the bottom of his mast. We made a "dam" around the base of the mast and tabernacle and filled it with Cuprinol, topping it off as it was "sucked" into the wood. The "original" formulation of Cuprinol discolors the wood but better a green dirty look than loosing your rig in a blow.

Contact with damp soil is a powerful rotting climate. So often folks think that railroad crossties are suitable construction materials where they contact damp earth. 'Taint neccessarily so! Railroads use ties atop well drained gravel beds, not in contact wth damp soil. Sometimes they will decompose deceptively quickly in contact with moist dirt.


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[SteveBenson]

http://www.postprotector.com/

[Pat]

Steve, I don't know if that is what they used or not but it looks like it, at least by my casual drive by inspection. If most of the advertising hyperbole is basically true than these post protectors are great stuff.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]