I'm remodeling my attic and planning to put the toilet about 9 feet from the main stack. It's a straight shot, but the joists (2x8s) run perpendicular to the path of the drain pipe, and what little I know of the code says that you shouldn't bore 2x8s for 3 inch pipe.

One of the solutions I had in mind was to frame a channel through the joists. I would sister the joists outside of the ones that I need to go through, and install double headers between the sistered joists. In the process, I would remove 18 inch sections from the problematic joists, leaving me a nice clean straight channel between the toilet and the main stack.

Any ideas if this would work? I want to be sure of the structural integrity of the plan as I intend to lay a ceramic surface over it all. Any better ideas?

Thanks everyone, Craig

My code allows a 30% notch in joists for pipes. On a 2X8 that comes to 2 1/4". A little shy of the 3 inch you wish to run. You propose to head off the joists which would be acceptable in my area. Good luck, Tom