Basement Bathroom Plumbing Installation

Discover the main steps of installing basement bathroom as a DIY project if you are a real pro.

Locate the main drain run. (look for a 3- or 4-inch main “stack” coming down one of the walls).
Find a sewer clean-out fitting by the wall facing the street or driveway.
Mark the floor to show the drain run and where you want to do your shower installation, toilet and sink drains.
Break the concrete along the main drain with a sledgehammer.
Dig an exploratory hole (2 to 3 feet across) or two where you assume tying in new plumbing to the main drain.
Verify the planned bathroom plumbing installation.
Make necessary changes to the layout, and clearly mark the floor with the locations of new drains.
The pipe runs should have a slope of ¼ inch per foot (or ⅛ inch per foot according to local codes).
Make sure the longest run of the drain has a sufficient height above the main for the run.

Break out the concrete for the new bathroom drains. The shower needs added depth to accommodate a trap, both the toilet and sink have their own traps. Determine how to run the vent pipes.
Remember, every drain has a vent pipe and code. Any pipe under a slab has to be 2 inches (except the toilet drain, which must be 3 inches or larger).
After digging assemble the pipe. Do not glue anything.
Break into the cast iron drain to assemble the Y-fitting with a pipe snapper.
Use a hacksaw if you work with old crushing cast iron
Cut out the appropriate length to accommodate the no-hub Y-fitting
Assemble the drain system. Make sure the downward slope, and the vertical location of the drains are correct.
Inspect the new drain system. Get the approval of the building inspector before filling the drain trench.
Fill in the holes to 3 inches below the floor. Pour 3 inches of concrete to replace, and level the floor.

Frame the bathroom.
Run the vent pipes from each drain.
Do not concrete the area surrounding the shower drain. Leave it open if you need to reposition the drain when the shower pan is framed in.
If the drain is correct, finish the concrete.