What's the consensus on having pex under the saw cut control joints in a slab? Some say just don't worry about it, some say don't do it and some say do it only if you have to and then sleeve the tube where it crosses the joint. It seems to me that if the slab has rebar or mesh that the steel wouldn't let the slab shift when the control joints crack unless the subgrade was not compacted properly. What do you guys who put in miles of the stuff say, and do you ever see tubing fail due to concrete cracking?

The only times I have seen pex fail in a slab are; hit by a jack hammer, drilling for anchor bolt, concrete saw, or helicopter trowel to close to manifolds. Know where your pipe is in relationship with where you will be placing future walls, structural posts, machinery fastenings.
I have laid pipe parallel to control joints when I have been concerned, consider this approach.
Sub soil compaction play a part on how your slab will move, Rebar and or wire mat will minimize movement.
There are people out there that sleeve, Perhaps one of them will offer a counter and technique to my opinion...?
Dan

I've never had a problem yet. Hey Dan what is the specs on Pex regarding streching? How far can it go and what are the manufactures telling you about performance under these conditions? Control joints rarely move more than 1/4".

Tom Pittsley
ecobuilder@aol.com
www.eebt.org

PEX, as you might guess, expands and contracts a lot more than concrete does over a similar temperature range. the issue with control joints is potential shearing if something were to move in a vertical plane instead of along the length of the pipe. Say one slab rose up slightly compared to another.

it is most common to sleeve tubing at control joints, or "dive below" the control joint in large slabs as well. For a simple sawcut, you can safely ignore them.