Re-route Vent Pipe

I am currently in the process of remodeling our bathroom. The wall that the sink and toilet are on is being moved back 2 feet to give our small bathroom more space.

Directly behind the toilet hidden in the wall is our friend, the 4" cast iron vent pipe. In order to move the toilet back 2 feet, flush with the wall...I need to re-route that vent pipe and move the flange.

I would like to cut the pipe below the floor level, put a bend in the pipe to run horizontal 2 feet, then vertically 8 feet, then run horizontal again connecting back in the attic.

My question is, where should I cut the pipe? Can I cut it below where the toilet vent comes in?

By the way, I do plan on replacing all pipe above the cut with plastic. ABS ok?

Edit: posted in wrong forum

toilet

From your description, and your question, you are doing a DIY job that you don't have the experience or knowledge to do it. Since there is a toilet involved you cannot just move the pipe back 2' without a lot of other work and fittings.

You might want to post some pictures and/or a sketch so we can better help you. CI to ABS (or PVC) is usually fine, but we'll need more info to help you DIY.

OK, change of mind. I have read up on this subject and asked some friends who are contractors.

I still plan on moving the vent pipe back 2 feet. There already is a cut in the pipe connected with a no hub boot. I plan to remove the pipe above the cut, replace it with 4" ABS, angle it 45** for about 1.5 feet, then another 45**, then straight back up through the roof.

My question is, is it okay to come straight out of the roof with 4" or do I need to reduce it to 3"

This is what I found when the wall was removed. If you notice, the sink has a drainline but no additional vent line. When I reroute this, should I include a vent coming off the drain line or leave it the way it is?

vent

When you go through the roof, you either HAVE to keep it the same size or larger, never smaller. If you know enough to move the pipe 2' and still make the toilet work, then you should have no problem with the sink drain.

hj said:

When you go through the roof, you either HAVE to keep it the same size or larger, never smaller. If you know enough to move the pipe 2' and still make the toilet work, then you should have no problem with the sink drain.

Click to expand...

Thanks HJ, I appreciate your help. BTW, disregard the last question I asked...the sink drain is the last fixture on the stack so it is a shared vent/drain.

I will say one thing...I have full respect for your profession. This stuff is a pain in the butt. lol