post and pier

[chad]

Just a quick question,If you put treated posts in  the ground below frost line and fill in with concrete,will the treated post still want to rot or lesson its life span due to water and moister being absorbed through concrete?

[PEG688]

 Short answer , yes.   Eventually they will rot, but lots of pole barns get built every year , generally they use , at least , 6x6 posts. So the hope is the post size will extend the post life.  The theory or track record is a 6x6 will out last a human's life time, so I guess that's where the "life time" guarantee part comes from.    

 Some  say you should put a layer of drain rock , 1 1/2" minus or pea stone at the bottom of the hole , say 6" to a foot, so a little bit of "over" digging , the extra foot or so, then set the post in the hole , then the concrete. This , hopefully, allows better drainage , so less rot potential for the post.      

[chad]

Thanks alot peg.Very helpfull!

[Don_P]

To add a little bit, rot requires food, air, temperature, and moisture. Deny fungi any one of those and it won't rot. Treatment attempts to poison the food. But, if you've noticed fenceposts or any buried post, they usually rot right around ground level... there is not enough oxygen at the bottom of the hole for the rot to do its work. That's also what ponding logs or spraying the huge piles at a sawmill is doing, the water is keeping the air away.

Remember the concrete goes under the post not just a collar around it. The concrete or gravel bed is spreading out the footprint over a larger surface area to keep the post from sinking. Load moves through both of those at a 45 degree angle. So, however much the footing is projecting beyond the post is also the minimum thickness of the concrete or gravel layer.

[Redoverfarm]

Just a quick question,If you put treated posts in  the ground below frost line and fill in with concrete,will the treated post still want to rot or lesson its life span due to water and moister being absorbed through concrete?

Just a touch of what Don_P stated and that is to bevel the concrete up the post to shed the water away.  Then if you are so inclined to wait until the concrete has shrunk a little and run a bead of caulk at the top edge of the concrete and post will prevent a little water from entering between the two.  When I set fence post I always tamp the dirt on a bevel around the post to shed the water away.

[chad]

Thank you,thats something ive been wondering for some time and see folks do it all the time.Thanks donp for the science lesson it makes total sense,I no atleast 1 person thats going to ask me about the rotting,so i can tell them that and sound like a brainiac ;)Also thats a really good way of sealing it off with caulk.redover.Now that im thinkin about it what about painting the treated posts about 10 in.or so above ground level.Would that eliminate the need for caulk and prolong the posts longer?      Thanks guys appreciate all the usefull info.