slab in pole barn. what to do with poles?
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ThistleKop
Silver Member
I agree with Kevin. Notching the posts and letting the "eave girts" rest on the post and using serrated, hardened nails to attach has worked well for me. If available, I use round poles discarded by the utility companies in the area. However, I'm selective to get good ones. I believe square or rectangular posts would make the project easier.
TK
TK
Dargo
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I've only caught the tail end of this thread. However, I do agree with the notching of the top of the posts and lag bolting the truss to the tops of each post. I had Amish builders frame my building. I have a ceiling height of 16' and all of my posts are 8' on center with 4' buried underground. I suppose that there are dozens of theories on how to set the posts. The Amish drilled 14" holes 4'6" in the ground, put in 6" inches of gravel in the bottom, put in the posts, and then filled up to ground level with gravel only.
I at first questioned the use of no concrete, and they were very sure of their process. I did do all of my plumbing, adding floor drains etc., added a plastic vapor barrier, added 6 gauge wire matting, 1/2" rebar on 6' centers and then 8" of 5000 psi concrete. At the overhead doors, they poured the concrete about 16" thick with numerous runs of rebar through it. They said that most all of the stress will be when heavy equipment bounces up into the barn and that is where the most strength is needed.
My barn has been there for 10 years and has withstood numerous wind storms of 80 mph plus without any ill effects. I have several cracks in the concrete, but it certainly is not heaving or the cracks are not separating. I was told to expect that. They promised me that the concrete would do two things; get hard, and crack. It is up to how you pour it to assure that the cracks do not cause any problem or widen or move up or down. Good luck!
I at first questioned the use of no concrete, and they were very sure of their process. I did do all of my plumbing, adding floor drains etc., added a plastic vapor barrier, added 6 gauge wire matting, 1/2" rebar on 6' centers and then 8" of 5000 psi concrete. At the overhead doors, they poured the concrete about 16" thick with numerous runs of rebar through it. They said that most all of the stress will be when heavy equipment bounces up into the barn and that is where the most strength is needed.
My barn has been there for 10 years and has withstood numerous wind storms of 80 mph plus without any ill effects. I have several cracks in the concrete, but it certainly is not heaving or the cracks are not separating. I was told to expect that. They promised me that the concrete would do two things; get hard, and crack. It is up to how you pour it to assure that the cracks do not cause any problem or widen or move up or down. Good luck!
varmint
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Ah, concrete and cracking. As a "retired" architect, I do know a few things, and concrete shrinkage cracking is one of them. You have to install some means of concentrating the inevitable stress cracks that occur as the concrete sets up and shrinks, and in most areas the rule of thumb is no slabs larger than 20' in any one direction without a control joint- even a sawn line, 1/4 or the slab's depth will work. 16' is safer still. Of course, water content/temp/humidity issues all can haunt you, but shrinkage is one thing to expect and plan for.
Westonium
Silver Member
My approach:
* attach some pieces of galv steel to bottom of post to firmly anchor to the concrete
* paint the buried part with 2-part epoxy or oil based waterproofing stain
* use a tube form big enough to accomodate the pole and steel pieces
* fill the form with concrete with water proofing additive - big difference than plain concrete
As for concrete slab integrity - use rebar set on risers (forget the masonry term) to center it in the concrete. A wire mesh sitting at the bottom of the slab wont do diddly for integrity, and pulling a wire mesh through the wet mud in an effort to sink a mesh in the approximate middle of the slab actually weakens the pour considerably. If you keep the pour properly moist (plastic over the top and/or water mist on hot days), and use a drier pour (its counter intuitive I know - using a wet pour on a hot day just gives you a weaker pour), you should have little to no large crack issues. You will want expansion joints, but you can actually just add those with one of those walk-behind concrete saws after the pour is considered walkable - but don't wait too long or you'll get a crack where you don't want it. The benefit of the cutting method is that you can snap chalk lines and do the cuts on diagonal, or in a grid, or any pattern you like. You are basically just scoring the concrete so any cracks happen where you decide them to happen. If you think you have a weak pour - put them closer together. Having pre-placed expansions limit that. On really large pours, I've seen both done in combo, but I prefer the cuts.
While I'm ramling abour concrete - rule of thumb is: If its nice and workable and easy to pour and work, it is too wet. It needs to be dry enough that its still ultimately able to be finished, but is a real workout and a PIA to deal with. This minimizes shrinkage. Water added (misting) AFTER setting will aid curing and hardening.
If you use steel poles, I'd still reccomend water proofing the poles in some way.
* attach some pieces of galv steel to bottom of post to firmly anchor to the concrete
* paint the buried part with 2-part epoxy or oil based waterproofing stain
* use a tube form big enough to accomodate the pole and steel pieces
* fill the form with concrete with water proofing additive - big difference than plain concrete
As for concrete slab integrity - use rebar set on risers (forget the masonry term) to center it in the concrete. A wire mesh sitting at the bottom of the slab wont do diddly for integrity, and pulling a wire mesh through the wet mud in an effort to sink a mesh in the approximate middle of the slab actually weakens the pour considerably. If you keep the pour properly moist (plastic over the top and/or water mist on hot days), and use a drier pour (its counter intuitive I know - using a wet pour on a hot day just gives you a weaker pour), you should have little to no large crack issues. You will want expansion joints, but you can actually just add those with one of those walk-behind concrete saws after the pour is considered walkable - but don't wait too long or you'll get a crack where you don't want it. The benefit of the cutting method is that you can snap chalk lines and do the cuts on diagonal, or in a grid, or any pattern you like. You are basically just scoring the concrete so any cracks happen where you decide them to happen. If you think you have a weak pour - put them closer together. Having pre-placed expansions limit that. On really large pours, I've seen both done in combo, but I prefer the cuts.
While I'm ramling abour concrete - rule of thumb is: If its nice and workable and easy to pour and work, it is too wet. It needs to be dry enough that its still ultimately able to be finished, but is a real workout and a PIA to deal with. This minimizes shrinkage. Water added (misting) AFTER setting will aid curing and hardening.
If you use steel poles, I'd still reccomend water proofing the poles in some way.
ronbo3
Bronze Member
I am facing the same dilemma--how to pour a slab in a pole barn. I'm almost finished with the framing of the barn, and the slab is my next step. I found info in the book "Practical Pole Building Construction", by Leigh Seddon, p.28. It has a drawing of his ideas when pouring a slab in a pole barn. The slab should not touch the poles, since the concrete will expand in hot weather and push against the poles--not good for the barn!!
Keep us posted on your slab. I want to know how others do this before it's time for me to spend my $$$!!!
Keep us posted on your slab. I want to know how others do this before it's time for me to spend my $$$!!!
bones1
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Any updates on this?
MikeD74T
Veteran Member
"I guess that one question that I have is, if steel would work as a replacement for wooden posts, (and it looks to me like it should), why doesn't anybody use it???"
Because barns are built by carpenters, not ironworkers. Kind of the same reason you don't see many brick barns. Mike
Because barns are built by carpenters, not ironworkers. Kind of the same reason you don't see many brick barns. Mike
ericbx1500
Gold Member
My pole barn is 5 years old (24x32). I used 4x6 .60 treated post with a concrete pad in the hole and backfilled with dirt. Also when I had my floor poured I did not use any expansion product between my post and slab. When my slab dried completely it naturally left a 1/16 gap around my poles and skirt board. I then went around a caulked the perimeter with concrete filler, which stays flexible. I also had expansion joints sawed. One down the center (24’ width of barn) and two on the (32’ length) of barn. These sawed joints have hairline crakes in the center of them so they have done their job. I have not one crack in the floor (lucky me). I have had no problems what so ever with movement. I believe a lot depends on soil condition and grade for runoff.
landman
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Ive been having the same questions, I just cemented the posts in, and used L brackets on two side the tie the posts to the slab. Rebar in the middle on two foot or so centers. Hopefully this will work my barn wont be closed in for a while, so i will have a very large sail area!