I have seen a suggestion on a DIY site to install thermal mat by taping it to the floor (as in your instructions), but then, instead of embedding it with a modified thinset as in your instructions, covering it with self-leveling cement. (I believe the idea is to eliminate the chance of causing damage with a trowel.) Alternatively, I’m considering using the thermal mat with the Ditra flooring material from Schluter. On their website, their installation instructions say to embed the mat in latex p.c. mortar. (In either case, the substrate will be plywood or OSB.) Given that neither of these installation methods follow WarmlyYours’ installation instructions, would using either of them void the WarmlyYours warranty?

MJS,

I think I sent an email to you in response to this, but it wouldn’t hurt to have this answered in the forums. I generally don’t recommend using tape to hold the heating mats in place. If there is any dust or debris on the subfloor the tape wont adhere properly and will cause problems with the thinset bonding to the floor. I’ve found that you can eliminate this worry by using hot glue or liquid nails to stick the mats to the subfloor.

As far as an installation with Ditra goes, we recommend you follow Ditra’s installation instructions. Last I remember, they suggest using a non-modified thinset, but I would confirm that in their installation manual.

-Seth