Very true Pat,
We use two types of underfloor heating systems over here, the first being the type a flexible element that is tied to the rebar before the concrete is poured for the floor slab.
The other sort, is glued to the concrete before tiles are laid.
We also have a similar sort of thing that fits under carpet, before it is laid, but I wouldn't personally touch that with a 10 foot barge pole, the thought of having a hot element under flammable carpet material, doesn't impress me at all.
But back to the topic, I'd personally test the element before and after the installation of tiles or whatever is being laid over the top takes place.
BTW, Kelley, welcome to ECN!.
