Isolation membrane required?
I'm about to tile a slab floor in a condo that's 90 years old. The old tile and mortar bed were about an inch thick, and has been removed. I installed a heated floor mat, and then poured floor leveler on top of that. I have been using it for a few years now, and love the heated floor experience. I have noticed that there are hairline shrinkage cracks, but nothing open.
I now have about 3/4" to get to the correct height for the toilet flange to be at the correct height.
The tile is 3/8" x 12" x 24" gauged slate, and the floor area is only about 5 feet x 5 feet. I plan on using Customs ProLite large tile thinset, and spetralock 1 premixed grout.
Question I have is, would you do an uncoupling mat like Schluter's Ditra because of the hairline cracks in the floor leveler, and if so, do you think it would effect the floor heat significantly? If it is recommended, can I use the same thinset on both sides of it, or does it need a special adhesive to get it to stick to the floor?
Thanks for any advice,
Burt
If you need to get the height up you can use Ditra XL. That would probably get you a 3/4” finish. ProLite should be fine to use on both the bottom and top of the Ditra. But wait a full 24 hrs before you walk on the tile. 48 hrs is probably better.