OT Setting posts for pole barn

[Pete in OH]

I"m about to start on a barn and wondering what you guys think is the best way to set 6x6 posts. 10" diameter holes 36" deep with a concrete pad at bottom and backfill with some gravel then dirt. But I"m told the PT lumber sold today will start to rot in 10 years or so. Or same holes filled up with concrete and use 5/8 anchor bolts and some StrongTie brackets. But I"ve heard that"s not as strong for wind loads and is more $$$. Any opinions?

 

[lha]

The resistance to wind is dealt with by lift resistance in peirs,and racking resistance in the walls and roof. This can be controlled by cables from bottom to top diagonally in x patterns,with turnbuckles to take up slack due to settling over time.If the walls can't move,they'll stay put.---lha

 

[gutterman]

(quoted from post at 02:07:07 08/11/10) I"m about to start on a barn and wondering what you guys think is the best way to set 6x6 posts. 10" diameter holes 36" deep with a concrete pad at bottom and backfill with some gravel then dirt. But I"m told the PT lumber sold today will start to rot in 10 years or so. Or same holes filled up with concrete and use 5/8 anchor bolts and some StrongTie brackets. But I"ve heard that"s not as strong for wind loads and is more $$$. Any opinions?

i have built a lot of post frame buildings, and i would like to think that i have seen it all, when it comes to post setting. one customer insisted we set 5 gal buckets in the holes before standing up the post's. another wouldnt have it any other way except we wrap each post end with 30# felt paper, still another had to have plastic trash bags around there posts.still another had steel sleaves made for the post to fit into under ground..... i like the idea of 30#felt best, just because its easy and keeps the cement from touching the post. i have alwase liked the post hole bottom filled with about 4'' concrete and if you have any doubts about the sureness of the footing you can taper the hole to make the bottom bigger.make sure its plum, then brace in at least 2 directions. fill the hole with cement. i notice some builders dont deduct 3'' from the length and width while squaring the post's. depending on the size and style this can make for some trouble when lath time comes. btw. make sure both sides are the same finished length, or your "gutterman" will laugh at you, if one side is 4'' longer than the other

 

[Devious]

I have some history with the green P/T 6X6 and I sunk them 4 ft and poured concrete around them about 4 inches wider on all four sides. They are still not showing any signs of rot and it has been 13 yrs now since they were planted for security fence corner posts with a few in between the 4X4 posts. I noticed yrs ago that they werereplacing the piers in Corpus Christi Tx and they were using large round posts with Plastic pipe PVC type of a larger diameter around them then they poured concrete around them inside the PVC and they had good results against rotting with the concrete around them under the water and above the water about a ft to fight the waves. I noticed the fence builders here in Houston NORMALLY pour concrete around the fence posts in subdivisions when they rebuild them after a hurricane or storms that blow them down. I am told some Insurance Cos. require it to be that way to pay off on a claim. I have rebuilt my back fence myself using concrete and the hurricane IKE blew my neighbors fences down on one side of three houses but my fences all stayed up. No Brag Just Fact. I used plain ole Quik Crete from 60 lb bags (The 80 lbers were just more than I wanted to handle) Devious

 

[Den N Ms]

Pete,I have sold and built many pole barns in years past.Good pressure penta treated 6x6s will last 40 years or more.I use to set the poles almost 4 foot deep,and dunp a 90 pound bag of Quickrete in the hole,level the pole,dump another 90lbs bag around tall 4 sides.Thin add dirt,tamping every shovel full till the hole is filled.The Quickrete will draw moisture from the ground and setup solid around the pole,just like if readymix was used.

 

[Quazar73]

6x6 is overkill most of the time.. Save your money and go with 4x6. I put up a 30 x 30 and a 30 x 40. No problems with wind ever or rot.

 

[lha]

I was a commercial and industrial carpenter[IBC&J of A]for 30 yrs,and a contractor+-10yrs,wrapping poles in plastic bags or felt paper might let people sleep better,but water will seep in. sitting in a water sealer overnight would protect the posts better.I have built pole barns for myself and others,and sunk 4x6's with 1/2"rebar imbedded in the sides and a wrap of fence wire to keep the concrete from breaking from wet-dry cycles and movement.---lha

 

[TheOldHokie]

(quoted from post at 21:41:06 08/10/10) Pete,I have sold and built many pole barns in years past.Good pressure penta treated 6x6s will last 40 years or more.I use to set the poles almost 4 foot deep,and dunp a 90 pound bag of Quickrete in the hole,level the pole,dump another 90lbs bag around tall 4 sides.Thin add dirt,tamping every shovel full till the hole is filled.The Quickrete will draw moisture from the ground and setup solid around the pole,just like if readymix was used.

Hey Den,

I once thought 40 years was a long time - not so much anymore :wink:

TOH

 

[don't_know_nothing]

a guy painted his ground posts with the rubberized truck bed liner to about a foot above the ground to try to protect them.... I think he had more money then sense though....

 

[Pete in OH]

I"ve heard of people coating the posts with used motor oil. The price is right but the environmental impact is questionable. Just don"t want the poles to rot.

 

[Gramps in NM]

Over the years (a lot of them) I have soaked post bottoms in thomsons water seal and set in hole when it was still wet. Then filled with concrete. Never had a problem.

 

[Zion Ute]

Pete: Some thoughts on your questions and previous comments... Bear in mind that your description of this is a "pole barn" and they can come in all sorts of sizes. Not sure if you have something in mind of the size of a single car garage or 10 times that.

Either way of setting the 6x6 poles would work. Setting the 6x6"s into the concrete will help provide some lateral (wind) resistance but you will still likely need some above ground bracing. Depends on how tall this barn will be.

That said, if you do put them in the ground do pour concrete around them (2,500 psi is code min.) as it will not compress with lateral movement as gravel would. Code - and common sense - says to make the footing low enough to get below the frost line. That may be 36" where you are, but please check. I"d provide more concrete cover than the 2" you"ll get with a 10" dia hole. I"d like at least 4" cover (14" hole) or 6" (18" hole). Posts set in concrete in the ground should be pressure treated, per code.

6x6 or 4x6 - what matters here is height and spacing. You didn"t mention either. Makes a difference too for that concrete pad at the bottom of the pole. Code says min. 6" thick x 12" wide footing for light frame WALL, like a stud wall. If your post is every 4 ft, or 6 ft. you"ll need something wider and thicker.

Putting some waterproofing on the post below grade won"t hurt. Your most vulnerable spot is the square cut end at the bottom. Make sure the top side stays dry too, so you dont" get water in that little crack between post and concrete surround.

 

[Woodchuck]

Keep in mind thatt preassure treated wood changed in 2004.
http://www.strongtie.com/ftp/bulletins/T-PTWOOD08-R.pdf

I use something like Copper Green wood preservative on ends and anywhere I make a cut in the wood.
What I've seen done and done myself for a pole barn is to use treated 2x6s laminated together below grade
(better penetration of treatment). Offset the ends that come above the surface about 2 feet and extend the poles with SPF 2x6s.
No point using more expensive preassure treated where you're putting a roof over it anyway.

 

[soqueu]

I have a 25 year old pole barn and the only rot I see is the cypress roof trusses sagging under a 5v crimp galvanized metal roof. The pressure treated poles still look good.