Time for pex!
So I found LoopCAD and they had a free trial, so I took advantage and designed my layout. I researched and learned that it is best to keep each loop as close to the same length as possible (300ft is recommended), so it took me a few iterations but I got it pretty close.
I know guys that lay pex very fast and very sloppy, I figured what's the point to the CAD design if you don't follow it. So I was very meticulous and followed the design to a T. I built a simple spacer to keep my runs 1' apart. It worked very well to staple the pex to the foam. I rented the stapler from blue ridge, which is where I got the pex. Blue Ridge has LoopCAD and will do a layout for you for free if you order your pex from them. I did that as well but ended up going with my design instead. It took a couple days to lay the pex. Make sure you finalize your design before you order the pex to reduce waste and save money by getting the correct combination of lengths of pex.
My best routing design made the manifold locations not on an outer wall (interior walls), so I had to come up with a way to support my manifolds so I could pressure test everything before and during the concrete pour.
I ended up driving 2 stakes through the foam and into the ground. To that I mounted a 2x6 with holes drilled for the pex to come through and keep things organized. I used some small 90 degree PVC elbows for where the pex comes out of the concrete for protection and to keep the pex in order.
Here are my 3 manifolds for my 3 zones. 1 zone for the larger shop area, 1 for the woodshop and 1 for the bath and game room.
I suggest pressurizing your zones well before concrete and fix any leaks at the manifold. I also suggest pressurizing the lines right before the concrete starts to pour, that way if they puncture a line you will know and might have time to fix it. I'd buy the parts needed to splice a pex line to fix a leak ahead of time in case something like this happens. Otherwise you will just have to live with a loop not working. Depending on the size of your zone this could be 50% of your room!
I went with rebar every 2'. I forget the diameter off hand. Make sure they sit the rebar on chairs if you do it like I did to keep the rebar more in the middle of the slab instead of at the bottom.
I decided to go with 5" of concrete.
One thing I would recommend is getting some plastic wrap (Menards) and wrapping the bottom part of your pex at the manifolds to keep the concrete off it all.. they are messy.
The relief cuts were put in at approx 8-10' sections. No need to worry about hitting the pex since it is at the bottom of the concrete and they only cut down like an inch and a half.
