Pole Barn Slab Questions

[CurlyDave]

Danged if everyone of those slabs did not crack in the center (parallel with the length of the aisle). It is a horse barn but I had gone with 6" just in case I wanted to run through with heavier tractors and such.

That has been exactly my experience with wire mesh. Every slab I have seen done with wire mesh has cracked, if rebar is spaced properly they do not crack. I always use 1/2" rebar on 18" spacing. I know this is overkill, but I hate looking at cracked concrete, especially if I am the one who under designed it.

 

[kn6md]

I am not clear on how it is possible to:

"* plan to put radiant heat pex tubing in at time of pour"

I put 3/4 inch PEX in my 5 inch slab, and had to tie it about every foot or so to the wire mesh with plastic wire ties to keep it from surfacing once the cement was poured on top of it. The slab was about 30 x 50 and it took me several days to do the PEX placement/tie down, consisting of I think four equal runs of 100 yards each.
The contractor was pleased with the tie job, as there was a pour nearby where the PEX surfaced. The home owner/builder would not listen to repeated suggestions to double or triple his wire ties. I heard about if from the building dept. inspector who said it was a sorry, sorry mess.
BTW, the PEX is pressurized to say 35 psi for a couple of days to make sure there are no leaks, and it remains pressurized during the pour so it does not collapse.
I used "fiber" to provide strength (contractor idea, I'm a bookkeeper) and agree that the wire mesh would be good if done right---which seems impossible to do. I needed the mesh on the bottom to hold the PEX in place.
It was interesting to watch the pressure rise due to heat generated in the cure process.
After cure, a 15k forklift drove all over it and there are still no cracks anywhere. It's about two years old now. Great ground prep is what the contractor said is most valuable. I did the prep work myself following the contractor's instructions.

Good Luck with your project.

 

[PaulT]

Re: plan to put radiant heat pex tubing in at time of pour

As opposed to "not at all", so I guess the "at time of pour" part was not necessary. I anticipate that it will take several days to attach the PEX, as you stated. I didn't think about the pressurization part, but that sounds like good advice.

Thanks all for the valuable and insightful responses.