Main Bathroom Drain Installation

I've started to install the drain system for the main bathroom. It's much easier to run the drain pipes parallel to the floor joists (i.e. in-between the joists), than to run them perpendicular to the joists (i.e. through the joists), but unfortunately I found it was unavoidable to have some of the pipes run perpendicular to the joists.

To install the drain lines I had to cut out some 4.5" holes in the floor joists. Although it seems that cutting such a large hole in the joist would weaken it, the engineering specifications for the joists do allow for holes of this size to be cut out.

Also, in an earlier post I mentioned that I was reinforcing the joists with plywood on one side so as to stiffen up the floor. Where I've had to cut holes in the joists for the drain lines, I'm installing the reinforcing plywood on both sides.

Ideally, the plywood reinforcement should be applied before I run the pipe through the joists... and for the most part I've done that. There are a couple of instances where I couldn't, so I'll have to cut some slots out of the plywood and fit it around the pipe afterwards.

Once I had the holes cut out, I started threading the pipe through in sections approx 12" long. The sections are joined together with ABS cement and a coupling fitting.



The odd shaped fitting on the right-hand side of the photo below is where the plumbing vent line will attach to the drain line.




A coupling fitting on the end.



That's a cleanout fitting on the right... to allow for access to the pipe in the unlikely event (I hope) that the drain gets really plugged.