The basic steps when installing a shower floor drain start with removing the old drain, checking the piping, and purchasing materials. The actual installation involves applying PVC prep compound to the pipes and drain, inserting and assembling the drain, and attaching the drain to the shower floor.
Start by removing the old drain from the shower pan, and checking the drain pipe for damage. Take notes, and make a list of the materials you need. Pay attention to what the drain pipe is made of and its diameter, the size of your old drain, and what the shower pan is made of. If the drain pipe is cracked or missing any seals, make a plan to repair them while you replace the drain.
The type of drain you choose is determined by the materials of the drain pipe and the shower base. Compression drains are made of PVC, ABS and brass, and are held in place with friction. Glue-on drains come in ABS and PVC, and are held in place with glue. Compression and glue-on drains are used with steel, fiberglass and plastic shower pans. Tile shower drains come in ABS, PVC and cast iron. They have a flange that bolts a waterproof membrane to a tile pan.
Any place where the drain and drain pipe are touching should be coated with PVC prep, and allowed to dry for 30 seconds before installing the drain. Insert the drain into the drain pipe, and install the drain base onto the drain. The drain base should line up over the drain. Finally, use the drain's hardware to secure the drain base to the shower pan.