I keep finding out I ned more! (and I THOUGHT I did my homework FIRST!!)
I am putting in a porcelain 13x13 floor with electric heat in my kitcen.
I insulated the joist good. I have 2x12's so I fit double r19's in there. I have 3/4 osb, a layer of thinset multiporpose, 1/4 inch backer.....
I NOW am seeing it is "reccomended" for an anti fracture?
Is this common for residential?
I am eventually putting electric floor heat cable in. I will be doing the two step method. ( sounds better for a novice like me!)
I imagine I need to do this membrane then set then after it cures, lay the wire on IT and then incase it in a thinset? before mudding and setting my stone right?
You can lay the heat system, fill it with self leveling compound and then apply a Ditra membrane of that before tiling. That method is covered in the Ditra installation manual. However, the concrete board is your uncoupling layer and the cable itself will give you some reinforcement as well. A mat would provide even more. It's just like putting a plastic lathe in. A separate membrane is probably overkill. If you hadn't done the concrete board it would make more sense to use the membrane.