Kitchen tile installation

After perusing this forum I now know particle board is not a suitable substrate for tile. My floor joists are 2' x 12" on 16" centers, and the floor is 5/8" particle board over 3/4" plywood (that's how we did it in 1975).

When I tiled my upstairs bathroom I tore out the particle board and replaced it with cement backer board. This stuff all weighs a ton. The bathroom wasn't so bad, but the kitchen and hallway are much larger.

I don't recall the thickness of Duroc, but I sm wondering if I can put this right over the particle board, and if so, how exactly. The problem with this is I will lose a lot of the toe space under the cabinets.

I also plan to install radiant floor heating, and am wondering if it would be advisable to install rFoil reflective insulation, and if so, where it should go. Reading the installation instructions on radiant heat sites, it appears they are encouraging installation over particle board, under carpet and wood floors, etc. I am very skeptical of these claims.

Thanks for any help you can offer. We all sure appreciate the time you take helping on these forums.

It's not okay to have particle board anywhere in your tile subfloor. So no, putting CBU over it will not be okay. Remove the particle board.

As for the radiant floor heating, foil reflective insulation would do NOTHING. Almost of the heat from your radiant floor heating is going to be due to conduction, which is a type heat transfer from one material to the next. Foil insulation would just stop heat transfer due to radiation of heat, which is not what happens with radiant floor heating. (Despite the name)

What type of radiant heating are you putting in? Is it going to be in the joist system, or above and in the subfloor? Because if it's above and in the subfloor, then you'll probabing be doing something like SLC or a Mud Bed instead of using CBU.

I am thinking plywood, then CBu with a layer of thinset, the radiant heating mats next, then another layer of thinset to set the tile in.

Sorry, I don't know what a mud bed or SLC is, perhaps you can enlighten me.

Thanks.

That's alot of Mud, LMAO.

Aren't you about due for a another cruise?

Nah, weathers getting nice here now, that stupid ice storm is just starting to melt away.