I am going to have some power poles milled into posts for metal building. Trying to decide whether to mount posts to concrete floor, over footing, or set them in concrete. Does anyone have experience mounting posts on top of concrete? If so what method/brackets did you use?

Based off what I've seen with pole buildings that anchor the post in the concrete, I would go with anchoring them on top of the concrete. Every older pole building I have seen with the post anchored in the concrete has showed them rotting off at slab height over time.
JMO

I would also put them on top of slab. We always use Simpson ABU66Z 6x6 Post Base. Also meets our building codes. Come in various sizes, either preset anchor bolts when pouring slab or use red heads if pre-existing slab

X2

Thanks for posting, I need to do the same and those above grade post holders look perfect.

Im not a builder but I do site work for such, Lately we have been required to have anchor footings and large anchor bolts on the ends of buildings built on a slab. This is for wind lift. This has been on residential only so far. Something to consider.

Thanks all!

I’m about 100% on going on top of concrete. I have set poles in concrete before and know how to plumb them up. I’m a little concerned about how to set the brackets in wet concrete correctly to be sure the posts end up plumb. Any tips there?

I struggled with this when I built my barn. Instead of poles having contact with concrete or ground, I imbedded u bolts in the concrete slab's haunch. Then simple walls attach to the floor plate. I also put a base sheet between the plate and concrete slab to eliminate any abrasion between the wood and concrete floor.

A new (last 20 yrs.) method used here is drilled 8 in. hole below frost line. Soni-tube (heavy cardboard tube) placed in hole extending 15 in. above grade. Fill with concrete to 10 in. above grade. While concrete is still wet place metal 6x6 holders for posts into top of concrete. The holders have metal rods with anchors to hold posts in place after concrete sets. Now you have concrete pillars with wood posts above grade. On my two 6 yr. old barns they are rated for 120mph. winds. Good luck.
Case.

I have used the above brackets but only for supporting center span locations.
On a corner I would prefer to set the post in concrete. Pressure treated or cedar posts at least 4 feet down.

On the other hand......it is a lot easier to locate the post for squaring if you locate it on top of the slab. If you go that route I would be certain to use a redhead on either side of the post. You haven't said how deep your concrete is or how tall these posts will be. Lots of leverage at the top of the post. !

I would also epoxy the redheads in place even though they don't necessarily require it

That’s kind of what I’m thinking case. Just without the tube and extension.

Heres the poop White. I’m planning on pouring a footing under where the posts are going, 4’ deep 6”-8” diameter with larger pad on top and a 1/2” rebar rod running the full depth. Posts will be 18’ tall. Only about 20’x20’ of the 40x60 will have a floor 5 1/2” thick.

I've done posts on top of footings with the Simpson post bases shown above, anchor bolts in the footings. I like to bring the sonotubes flush with the top of the slab to create a joint where the footing and slab can move. In NJ, we get freeze/thaw cycles all winter. Although it rarely happens, slabs can heave in the winter. I don't want the slab tied to the footing. In NE, I'm assuming that once the ground is frozen, it's frozen until Spring. Maybe slabs don't move there.

did you notch the post or is that 3 foot sections of post. Never seen that done .

I’m building it in NW Ontario so frost should stay all winter. Do you put an expansion joint wrap around the tube, or just use the tube to keep it separate from the slab?

I notched all the post. They are all true 6”x6” Amish rough cut hemlock. I wanted my hemlock siding flush on the inside.

My pole barn has posts concreted in the ground. Posts are made from 3 pressure treated 2x6's bolted together to form a 6x6 post. A standard 6x6 post does not get the treatment all the way into the center and thus rots from the inside out. Barn was built in 1995 in a wet spot and all posts are still as solid as new.
Trapset: if you are milling power poles make sure they are treated all the way thru. Poles around here are not..

My sawmill produces and treats residential telephone poles along with fence posts. If your solid 6x6 posts are not treated 100% three things, log was too big for milling a 6x6 (too much heartwood for diameter)
Wrong treatment chemical (non-human contact) Decks and railings of treated wood is treated different than posts. Third, moisture content too high prior to treating, pressure vessel pressure too low or time in vessel too short. Log size for a pole barn post should be just larger than finished post, that gives minimum heartwood. A straight 10 inch log should be used for a 6x6 post. All my timber is laser sorted to big end small end diameter. We do bore/core testing to certify.

But you will have a continuous footing around the entire 40x60 perimeter ?

Thanks

We weren’t planning on going all the way around with concrete White. We’re thinking about just pouring where the posts are then using ground contact treated 2x6 around the bottom and crushed stone inside except where the 20x30 slab part is.

I’m not against a footing all the way around, just not sure what it would accomplish. I think all the weight will be on the posts, therefore, the footing under them. Unless I’m missing something.