The Second Mud Layer Of The Tile Shower Pan
The tile shower pan is built from the bottom up. It's subfloor. Then felt and metal lath. Above that is the sloped deck mud layer, sloped to the drain. Then is the key layer, the shower liner membrane carefully installed. After the cement boards are installed on the walls, the second masonry layer goes over the actual liner membrane.
Made of the same deck mud as the first mortar layer, the top masonry layer also is sloped up from the drain to the wall at 1/4 inch per foot.
If the first layer of masonry is done correctly, the top layer will be uniform in thickness from drain to wall.
Here's the key...
The top layer should be at least 1 1/4 inches thick at the drain. That's to guarantee there's enough mass of masonry to stand up over time. That thickness plus the thickness of the tile and the tile thinset layer used to stick it down are going to determine where the floor height is and where the finished drain height is.
Just like the first masonry layer, deck mud is put in place then packed and scraped to a finished shape. This is your last chance to level the mud at the walls and get the right fit at the drain.
Care now makes for easier setting of the tile layer as the last step.
Make sure the shower drain is adjusted to the proper height.
The next step is positioning the tile shower drain.
To learn how...Click Here...