There are several options when choosing a shower drain for your preformed shower base installation. Your choice depends on your shower pan and your situation. And the type of pipes you have in your home and the manufacturer’s recommendations for both the shower pan and the drain may also help you determine which drain assembly to buy.
Keep in mind that shower drain assemblies are generally made to fit a 2-inch drainpipe, not the 1 1/2-inch pipe usually found on tubs. A 2-inch pipe is the recommended size because showers have a low threshold for flooding, and a 2-inch pipe helps the water drain faster than does a 1 1/2-inch pipe. So, if you are converting from a tub and shower combination to a shower, you’ll likely have to change the drain pipe size.