Hi all,

New subscriber here with a floor heat question..

A few years ago before I laid down my tiles, I installed PEX tubing for
radiant, hydronic floor heat. I tied the tubing to steel construction
grating, and covered my tubing w/ ~5-6 cm cement and sea sand
mortar.This was on top of the existing 15-20 cm slab, which is well
anchored to the ring beam. I did not insulate between slabs since I
wanted to also get some heat into the basement below. IIUC, this is
referred to as a "slab on slab" application. The tiles are ~5/8x11x11
inch terra cotta pavers. The area is about 80 sq. meters, fairly square
with four zones. Walls are 60 cm stone.

My main question is this. In some of the literature, they recommend
inslulating the perimeter w/ about a half inch of insulation, mostly to
reduce losses into the side walls, (and possibly to take up
expansion/contarction of the concrete?) Some other literature do not
consider insulating the the perimeter.

I did not insulate the perimeter, and do not care about losses through
the walls. I also did not add any fibers to the mortar which might have
added some crack resistance. What I am concerned with is the possibility
of "cracking" of the grout between the tiles, or even lifting of the
tiles. :-(

Can anyone give some feedback on this. I will be using an olive kernel
burner, that will mostly be on all the time, albeit on low temperature.
Olive kernel is still quite cheap in Greece....

regards,

nikos