Heated topping slab in exterior application

[catosborne]

Hey folks,

We've been tasked with installing a heated topping slab for a dog kennel in an exterior area. The kennels are on top of a twelve story building in temperate San Diego (over a heated hiving area), on a post-tensioned slab (ranging from 12 1/2 to 10 1/2 inches thick, sloping to a drain). The architect has requested RaySol heating cable, bare with no conduit --

http://www.tycothermal.com/usa/english/floor_warming/products/productdetails_comm.aspx?pcg=1720

-- and we've got a 3 1/2" depressed area to make use of.

My assumption is 1" rigid insulation over the waterproofing coat, followed by the bare heating cables, 6" wire mesh and 2 1/2" of concrete topping, with a 1/2" expansion joint where the topping meetings the exterior concrete walls. My concern is cracking due to expansion and contraction due to temperature differences.

Does this detail sound realistic?

 

[ishvaaag]

Laying the heating elements directly over the insulation will likely damage it if plastic; hence you need it be glass fiber, bubble or mineral. Then, in the description of the product they are drawing very thin mortar and ceramic tile floor directly over the heating system, so maybe it may be done, since they seem to have the appropiate mortars. I would ask the seller of the system directly.

Now, technically, you may analyze the stresses for one differential temperature between cable and whatever else you add to your setup. 3D FEM, set temperature at the cable, and include everything bottom to top, then find stresses particularly at the mortar, see if you have one mortar as good. But experience of the seller of the product may be more reliable and easier to use.