Mesh, Staples, or Both?

[Burl]

Seems like everyone (mostly) is tying their tubing to the mesh. Seems like a good way of keeping the stuff in place, probably the best. But is the mesh serving its purpose of reinforcing the concrete when its at the absolute bottom of the slab? Do people use a second layer of mesh? How good are the staples at keeping the tubing in place? Thanks for all replies.

 

[thammel]

My plan is to staple the pex to the insulation. Then the wire mesh will be laid on top of it and I presume the concrete guys will pull the mesh up to get it into the middle of the concrete. At least that is the plan. You can also buy "chairs" to set the mesh or rebar on and can tie the pex to that.

Tom

 

[boiler7904]

Mesh doesn't do anything for the slab when it's laying at the bottom of the slab. It needs to be between the point that is the bottom third and the midpoint of the slab to act in tension to reinforce the slab. In other words for a 6" slab, mesh has to be between 2" and 3" above the vapor barrier / base material to do its job (1 1/4" and 2" for a 4" slab) It should be installed on concrete bricks or metal / plastic chairs to keep it in the proper location. Concrete guys will hate you but that's what it takes to do the job right.

The staples only have to hold the tubing in place until the concrete sets up.

I've also seen plastic clips that screw into foam insulation. Then you just snap the tubing into the clips from above.

 

[5wndwcpe]

Mesh doesn't do anything for the slab when it's laying at the bottom of the slab. It needs to be between the point that is the bottom third and the midpoint of the slab to act in tension to reinforce the slab. In other words for a 6" slab, mesh has to be between 2" and 3" above the vapor barrier / base material to do its job (1 1/4" and 2" for a 4" slab) It should be installed on concrete bricks or metal / plastic chairs to keep it in the proper location. Concrete guys will hate you but that's what it takes to do the job right.

The staples only have to hold the tubing in place until the concrete sets up.

I've also seen plastic clips that screw into foam insulation. Then you just snap the tubing into the clips from above.

I agree with Boiler, do it once and do it right. Pulling the mesh up is of little value as it most likely will just sink back to the bottom anyway. Besides, if you tie the PEX to the mesh and then pull it up with a rake as you go, you not only run the risk of damaging the tubing in the process, you now have no idea how close to the surface it is in the slab. Stapling the tubing to the foam and using chairs or slab bolsters to suspend the mesh is the best way to go, IMHO. It protects the tubing and keeps it as far away as possible from any later penetrations of the slab surface. Think tapcon.

 

[69Cat]

I'm using 10mm (3/8) rebar on 18" centers with concrete bricks underneath to hold the rebar up 2" from the foam. I'm tie wrapping the pex to the rebar. Thus my rebar and pex will be close to being centered in the 5" slab. Hope to get the concrete poured later in the week. Can't find a concensus as to where in the slab the pex should be but its a given that the steel reinforcement must be near the middle and I didn't like the idea of pulling it up during the pour so am using the bricks to position it now. Makes for a convient place to fasten the pex. 18" centers gives room to step between the steel.