How thick is the heated floor mat?
StickyMat System – DWM
The heated floor mat by Warmup (NADWM) features an ultra-thin 1/8″ wire that does not raise floor levels.
Warmup recommends creating a channel for the heating cable factory joint in the subfloor so that it can lay flush. Once the heating mat and floor probes are down, it is necessary to fully embed the materials in thinset or leveler bringing you to a total thickness of 3/8″.
If you are interested in an installation video, you can see one here.