I am renovating a bathroom and installing radiant heat under a tile floor. The subfloor and cement backer board were installed without considering the finished height of the floor. What is a good way to ensure that the self-leveling cement is thick enough, but not too thick?
The floor is a long, narrow room, 5' × 12'. The heating mat covers 22.5 sq ft in the middle with unheated areas along all 4 walls. Per the mfg, Thermosoft, I have stapled the mat to the backer board over a plywood sub floor. Next I plan to embed the mat in a layer of self-leveling cement prior to laying 1-inch square tiles using thin-set. The height difference from the backer board to the adjacent hardwood floor is 9/16". Mat is 1/8". Tile 1/4". How do I make sure that my self-leveling cement is a consistent depth for the entire length of the room?
I am thinking using nuts that are the correct height and securing them in place every 18 inches with a recessed screw. When I pour the cement, I can let it come up level with the top of the nut. It won't matter if it's visible since the tile will cover this surface. Will this work?