SLC, heating cables, and lath: should be lath be under or over heating cables?
 

Here is a question that seems to have two answers, but I would like to hear solid reasons for each answer--rather than "that's the way it's done".

When installing electric radiant heating cables over plywood and embedding them in SLC, most SLC specifies that lath (plastic or metal) is required. The question is whether the lath goes below or above the heating cables. What are the reasons for doing it one way or the other? Is one method better (stronger, less likely to delaminate) than the other? Or is just convenience or convention?

I myself have put the lath above the heating cables, as I remember being instructed to do it that way somewhere--but now I can't remember where I learned this, so now I'm wondering.

Any thoughts would be appreciated.

Thanks!

Tim, it can be installed either way. Here's a little quote from TileGuyTodd's SLC and electric heat mat thread in the Liberry:

Putting the lath down first reduces potential problems with damaging the heat mat. Putting the cable down first allows the lath to keep the cable and sensor tight to the subfloor. Pick your poison.

The metal lath can be quite sharp, so watch the cables, regardless of which side you install it on!