The first step to finishing a basement bathroom is to obtain a building permit. This must be done whether the homeowner is doing the finishing himself or has hired a contractor. After this, the bathroom walls are painted and a ceiling ventilation fan installed.
The builder then installs a vent to the outside for the fan. Then, he builds the shower stall and tiles the walls and floors of the shower. After this, he can install the hot and cold water lines in the shower, and put in the shower head and the valve.
The builder should then install the toilet, the sink and the vanity. He adds the mirror and lights over the vanity. When this is done, he connects an electrical outlet to run the sewage pump. Because the toilet is below grade, sewage needs to be pumped up and out of the basement.
When the sewage pump is installed, the builder then connects the outside vent pipe to the basin that holds the sewage, and connects the sewage pump to the main drain line. He then connects the hot and cold fresh water lines to the main supply. After this, he makes sure that the water lines, sewage pump and other connections work properly, and then has the local building department come in and inspect his work.