Pole barn question

[TNhobbyfarmer]

I plan on building a modest sized pole barn sometime this spring, probably in the 20x35 range. I am not a real experienced builder, but I did previously build a similar sized pole barn on land I no longer own. On that one I put the poles down in holes and concreted them in.

I am considering mounting the poles on the top of concrete piers this time. My plan is to drill the holes, put a foundation pad in the bottom with a piece of L-shaped rebar sticking up, and then when the pad sets up, finish filling with more concrete. My thought is to mount 4x6 PT poles on the concrete pads using Simpson Strong Tie brackets on top of the piers. Does this sound structurally sound enough? I know I could do it the way I previously did it, but that wood underground always made me a little nervous.

By the way, after 10 or so years, that previous building never showed signs of not being sound. I hope the current owner is still experiencing acceptable performance.

 

[Roadworthy]

Your local building department will be able to tell you how it should be done. Someone who builds pole barns can probably suggest appropriate dimensions to maximize the use of materials, like the most effective dimensions near your proposed wishes. The standard here is 6 X 6 posts. You drill the hole, say twelve inches in diameter. Pour a two inch thick pad in the hole to support the post. Drive six to twelve galvanized sixteen penny nails halfway into each side of each post. This will prevent vertical movement. Put the post where you want it then pour a few inches of concrete into the hole. Backfill with dirt but not quite to the top. Finish filling the hole with concrete to a point just above the ground. That is roughly how it's done in Benton County, WA. Good luck on your project.

 

[BoylermanCT]

Technically you are building more of a post and beam building than a pole barn. The hallmark of the pole barn is buried poles. What you are proposing is certainly do-able. The key will be how far apart the concrete piers are from each other and what size beam you have spanning the piers.

I finished my 30x40 pole barn in 2021 and have been extremely pleased with how it turned out. That said, if I were building a smaller barn, I would look seriously at a Versatube metal building built on a concrete slab.

I would not backfill a pole barn with concrete. If the pole rots, you will have a terrible time replacing it.

 

[CloverKnollFarms]

When we built this year, we used post wraps, basically a thick plastic tube that surrounds the post when concreted in. They offered something much like you suggest. A concrete pier, with a metal bracket to secure the posts to the pier, which eliminates all post to ground contact.

 

[IXLR8]

I am getting ready to have a pole barn built here in the Eastern Shore of VA. The rule of thumb here is hole diameter 3x pole diameter. A 6x6 pole goes in an 18" hole. Pole is sitting on bed of crushed gravel, 4' deep then the hole is filled with concrete. I am leery of pouring concrete around the pole, worried about pole rotting, even if the pole treating is done to marine standards. But, that is the way all the pole barn builders do it here, seems to be the only way to get it past the Building Inspectors.

 

[jigs_n_fixtures]

Simpson makes moment transfer pole bases. Which replace the the portion of the pole which is normally embedded in the concrete bases.

You have far less issues with pole rot, and don’t have to deal with pressure treated wood for anything except the bottom plates, if you want to close in the walls.

 

[captainbars]

Having been a contractor/builder for over 25 years and having built several barn/garage structures similar to yours,
I have never had a pole rot from ground contact if done correctly. Depending on soil conditions at the site, dig the hole 2-3x pole diameter and 2.5-4 feet deep depending on size and height of structure. Fill bottom of hole with 6-8 inched of 1.5 - 2 inch base material (gravel, etc.). Set treated post and pour concrete to grade level. THe gravel allows moisture to drain away preventing continual contact with the wood.

I have limited experience with surface mount bases, but done correctly it obviously can work. Good luck!

 

[JJT]

Last summer I tore down the playset/swing/fort the kids and I built more than 25 years ago. It had a dozen pressure treated 4x4's embedded 3' in concrete. There was no rot. I've also pulled 25 year old pressure treated fence posts, no concrete and no rot. I wouldn't be too worried about ever having to replace a post.

 

[nybirdman]

We recently built two,24x30 and 30x40'.This is up North near the Canadian border so we have to deal with frost.We dug 4' holes with a post hole digger(14") poured a 2" pad on bottom,used a plastic sleave around post(Home Depot) and back-filled with dirt(not concrete).Buildings have not moved and post should never rot.
I have found on a previous build;if you pour concrete around the post the frost will"jack"them up.
Sonatube piers also would work+with metal brackets above ground.

 

[CloverKnollFarms]

Post rot at the soil surface where conditions permit it. The plastic sleeve extends above grade, thus eliminating that contact