The shower drain install techniques are simple yet really important. Most people are concerned about getting the job done right with shower stalls and shower pans so there aren’t any leaks.
I like this cutaway photo I did years ago that shows the different components of the drain assembly and the layers of mortar.It shows how involved the process is for building a mortar bed. There is basically one layer of tar paper, one layer of wire mesh, one layer of mortar, one layer of plumbing rubber membrane, another layer of mortar and finally the tiles.
The shower drain assembly is the first place to start. It usually comes in 3 or 4 pieces. The drain base is what we need to start with. This base will fit over the drain pipe. We’ll need to use ABS cement to make a leak-free connection with the drain pipe and the base.
It looks like this once its glued in place. It seems to stick up too far but the mortar for the shower pan will be fairly thick. At this point you will want to be sure the drain has a very tight seal. The pipe cement will help create a tight seal, but it’s really important to make sure the pipes and connectors have been completely pushed into each other when they have been cemented. I say this now because we are going to enclose those the drain assembly in mortar. It will then be really hard to troubleshoot leaks.
Under the floor where everything is normally hidden, the drain assembly connects to the P-trap. Here you will want to check for leaks as well before you start to pour the mortar into the shower pan.