I am replacing an existing tub with a larger tub in a second story
house. I was going to move the existing drain line back and branch
over to make the new drain connection. For clarity. imagine a compass.
The old tub drain is dead north and the new tub drain is due east - in
other words it is 90 degrees to the left from where it was.
Problem - a 6 x 14 header runs between the joists making it impossible
to make this tie in as I cannot weaken the existing header. A 3" waste
line for the toilet is in the same joist bay as the new tub drain and
on the other side of the header.
Can I cut the existing 3" toilet line and add a wye - 3 x 3 x2 and make
the new connection? The tie in would be 6' down from the toilet - I
can add another vent from the wye and tie it back to a 2" existing
vent. I would make the trap 11/2". Will this work or will I cause
drainage problems or back up with the toilet.
Your advise will be appreciated.