[massplumber2008]

You can cut into the stack and run a 3" or 4" pipe... either works here. I would probably run a 4" main trunk line and branch off 3" for each bathroom separately.

In this manner, 4" runs length of both baths with an end clean out and also has a cleanout back where it connects at the vertical stack.

Then basically, as pictured in the above picture for both bathrooms.

Keep me posted... and AGAIN... are you planning on doing this work yourself?

.

[MADIYer11]

Thanks for your reply and yes I will be doing this myself.

I have a few other question about venting.

There is a window in the current bath and will not be moved. There is about 38" of space between that window and the floor. I want to install my drain for the lav about 24" from the floor and send my 2" vent line up about 12" more and go horizontal for approx 18' until I pickup the current vent.

I want to do it this way so that I can pick up the vent in the current bathroom wall that goes up to the roof and avoid putting another hole in the roof. The current vent in the roof is 4". Would this be acceptable?

My next question is can I run the tub/lav drains off a wye on the toilet arm? The lav/tub would be vented, so would this be an acceptable vent for the toilet?

The layout for the drains would be a wye off the stack with clean out. 4" line to 4x4 wye, then to a 4x2 wye off that arm for the lav/tub. Same for the next bathroom and at the end of the 4" run install a clean out.

Does any of this sound acceptable?

[massplumber2008]

Hi:

Lavatory drain from finished floor is 20" to center of 2" x 1.5" sanitary tee fitting, then up and over as required....but you're not planning to run that vent 18 feet through studs/joists are you...??

You want to offset around the window and get vent pipe into the joist bay at the cieling if possible then run that pipe into attic and make connection at 4" or any 2" vent or larger. This way only drilling a couple holes and also reducing the horizontal distance of vent. Vertical unlimited in this case...horizontal distance exceeds limits..so try to go vertical as much as possible.

Yes you want to branch of the 4" trunk line with a 4" x 3" wye for EACH bathroom (then a 4" end clean out on trunk line).

Then install a 3" x 2" wye to pick up the lavatory and tub as in the picture in between that 4" x3" wye and the toilet elbow.

It is the 2" lavatory vent that WET VENTS the tub and toilet in each bathroom!


And layout is as follows (YOU WILL LIKE THIS):

NO NEED TO CUT INTO THE VERTICAL STACK HERE... I think you can cut into the 4" horizontal pipe that picks up the toilet. Originally when you asked us if could use that pipe we did not understand all information...but since you will be doing all of this over you can now simply cut the horizontal cast iron pipe once...;) , and attach onto it with a shielded clamp and you are ready to start!!

Then you will straighten the angle of that horizontal cast pipe out by installing a 4" street 22.5 or a 45 degree fitting (that should straighten the trunk line out). Then want to install a 4"x3" wye for first bathroom, run trunk line down abit and then install a second 4"x3" wye for the other bath, and then install an end cleanout at end of 4" run.

Then pipe bath as presented from toilet piping....be clear that there is no 4" x 2" wye here...;) Needs to be piped so it is inline with toilet!!

It will be tight fitting, but looks like pretty straight shot at all this. Just leave enough space off that back wall to run all this piping...I would stay about 3 feet off back wall with the 4" trunk line... then branch back toward each bathroom with the 4" x 3" wyes I talked about.

Let me know what you think...

[MADIYer11]

Hi:

but you're not planning to run that vent 18 feet through studs/joists are you...??

You want to offset around the window and get vent pipe into the joist bay at the cieling if possible then run that pipe into attic and make connection at 4" or any 2" vent or larger. This way only drilling a couple holes and also reducing the horizontal distance of vent. Vertical unlimited in this case...horizontal distance exceeds limits..so try to go vertical as much as possible.

Thanks A MILLION!!

Yes, at first I was going to run the vent through the studs, but clearly wasn't thinking about the structural integrity of that outside wall. So I will just send the vent into the attic and catch the current vent up there.

You just don't know how glad I am that I can cut that horizontal pipe off and use what's there... I will post pictures as I progress through this project.. I will be starting in about a couple weeks..

[massplumber2008]

Good luck!