Hello,

I'm new here and have found this site quite informative while lurking over the past couple of weeks.

I am in the process of converting a small office and guest room into a downstairs master bedroom/bath. I am trying to settle on a DWV layout that is simple and hopefully up to code. I am familiar with basic plumbing but not altogether up on the major plumbing codes. Hopefully I can tap into some of the abundant knowledge that is available on this site.

The basic toilet pattern that I planned to install for the new bathroom was to have the toilet connect to a 4x3 closet bend and then extend to a vertical vent/drain stack directly behind the toilet tank in the "wet wall". Other drains lines would also tie into this stack. This is similar to the way the rest of the house is configured. The house was constructed in the 60's and is built on a perimeter foundation with a crawlspace.

My problem is that there are obstructions (refrigerant lines, electrical, etc.) attached to the underside of the 2X10 joists directly below the wet wall. As a result I can't duplicate the toilet pattern that I previously described. The space between the joists is open however.

Therefore I am considering going straight down from the toilet flange with 3" PVC and drop about 24-28 inches and transition into a combo wye fitting that serves as a cleanout and forms the beginning of a new horizontal 3" drain line. This drain would then travel about 10 feet along the bottom of the crawl space, make a 45 degree turn and travel another 10 feet before tieing into the existing 4" cast iron drain line via a wye connection.

The vent line for the toilet would be a horizontal 2" branch connection coming off a combo wye (or santee?) on the backside of the vertical leg of the toilet drop and extend rearward to the wet wall where it would connect to a 2" combo wye fitting with the vertical leg continuing up inside the wall and eventually out the roof. The horizontal portion of the line would further extend rearward where it would connect to a the drain of a shower that is on the other side of the wall. This line would run parallel to the joists and be located mostly within the joist bay. Additionally, the 2" vertical vent line in the wall would serve as the drain for the adjacent pedestal sink (connected with a santee and a 1 1/2 drain line). The sink and toilet are in a small "powder room" separate from the shower and a single vanity. The shower p-trap would be within 2 1/2 feet of the vertical vent line and the pedestal sink p-trap would be within about 2 feet. Finally I would like to connect another 1 1/2" horizontal drain line from the vanity with the tie-in between the upper vent connection and the lower combo wye fitting below the toilet flange on the 3" vertical line. Due to the length of the 1 1/2" drain line(about 8 feet), the vanity lav would be vented by an AAV inside the cabinet.

To summarize, directly below the outlet of the toilet flange would be connected a horizontal 2" branch line that serves as a wet vent for the toilet and a drain line for a shower and a pedestal sink. Below that would be another horizontal branch connection that serves as the drain for the vanity sink. Both branch connections would be in the vertical section of the toilet drop.

My concerns:

1) Is there an issue with the straight drop from the toilet such as high velocity, separation of water/solids, etc?

2) The toilet is obviously at the beginning of the line. Even though the other branch connections are supposedly vented (?? ), is there a problem with the vertical drop causing a loss of the other trap seals.

3) What other problems or major code violations am I missing? Typical wet vents and AAV's are allowed by local codes.

Sorry for the long winded post. It is sometimes hard to visualize the plumbing layout from a written post, so I wanted to describe it in as much detail as possible. Thanks in advance for any help or advise that you can give.

Regards,

John

1) Is there an issue with the straight drop from the toilet such as high velocity, separation of water/solids, etc?
No, it's done all the time with second floor toilets.

2) "The toilet is obviously at the beginning of the line. Even though the other branch connections are supposedly vented (???), is there a problem with the vertical drop causing a loss of the other trap seals."
Not if the fixtures are vented per code.

3) What other problems or major code violations am I missing? Typical wet vents and AAV's are allowed by local codes.
Just bear in mind that each fixture that has a trap MUST be vented.

Good luck, Tom

Thanks Tom. I appreciate the quick response. One other question, is there a limit on the number of bends on a vent line? I can "snake" a 1 1/4" vent line thru some intersecting walls for the vanity instead of using the AAV, but it will have about six 1/4 bends in the line from the where it ties in the vanity drain to where it tees into the primary 2" vent in the attic area. I guess I not fully comfortable with using the AAV. Your thoughts?
Thanks for your help.

John

And I'm not comfortable with a 1 1/4" vent. You may put all the bends in a vent that you wish. However, if running a vent will put a hardship on you I would consider putting a AAV just after the lavatorytrap if local codes allow. Good luck, Tom

Thanks, Tom. I'll go with the AAV. I certainly appreciate all your responses.