I am in the process of trying to retrofit a DWV system for a cabin in the country. This cabin has a 3/4" plywood floor on 2x4 joists on 4x4 beams which sit on cinder blocks so that the floor is approximately 12" off the ground which does not leave a lot of room to work.

My questions are on venting and clean outs
1. can a wye (TY) have to be facing straight up or can they be rolled up on horizontal drains where the outlet runs parallel to or at a 45 degree or so rotation on the drain line?
2. can a wye (TY) used as a vent on a shower trap arm transition to a regular 't' on which another drain line can also vent?
3. when using a wye for a vent do you have to also use a 45 degree forming a TY?
4. can vent lines run horizontal underneath the floor then transition into a vertical vent going through the roof or re-venting into a stack? If yes, how much above the horizontal drain line should horizontal vent line be?
5. does a 2” 10-12' horizontal drain flowing into the main line need another vent if a vented sink trap feeds it?
6. can I put a clean out in the wall near the bottom of a vertical stack to satisfy the requirement for cleaning out the horizontal waste line under the house?
7. would a 10-12' line need a cleanout or could it simply be cleaned out by removing the p-trap?

I do not have very much space to work with and need to vent a couple of lines and want to provide cleanouts for ease of future cleaning and really want to do everything correctly. Any information you could share which may help with plumbing in tight spaces would be greatly appreciated. - James

Hi James...

Not to insult anyone, OK, but let's start by defining fittings? A wye fitting is shaped like a wye (1st image). A sanitary tee is shaped like a tee fitting (2nd image). A combination wye and 1/8th bend look like a really long sweep tee fitting (3rd image). A dandy cleanout (also called a test tee) looks like my last image.

Wyes and combination wye and 1/8th bends are for connecting horizontal drain lines into main lines. Wyes can also be used for vents, but most of the time we use sanitary tees. Sanitary tees can be used for drains off a vertical stack and can also be used on the horizontal to pick up vents.

Now, to answer your questions:... ;)

1) Sanitary tees can look straight up or they can be set at a 45 degree angle for venting purposes. Basically, the fitting needs to roll above the center of the drain line is all.

2) No need to add vent to the kitchen sink drain line as long as you are adding an AAV under the sink... even if it is 10-12' until it connects into the main drain line. While piping under the sink add a full-size dandy clean out or use a union type ptrap which has a full-size cleanout and you should be all set with the kitchen sink and the kitchen sink cleanout.

3) When using a snaitary tee fitting for a vent you can use 90s, 45s, 22.5 degree fittings... as long as the sanitary tee fitting is above the center line of the drain line.

4) Horizontal vents need to pitch back toward the drain line. If you are tight for space then you can make the vent almost level, but be sure to have some pitch.

5) No.. see #2

6) Sure can putting a dandy cleanout on the vertical under the vanity works well... same for the kitchen sink... right?

7) See #2

Remember to hang all pipes every 3-4 feet maximum... even the vents, and pitch all pipes at 1/4" pitch per foot if you can.

Back to you...

MARK
Attached Imageshttps://www.askmehelpdesk.com/attachments/plumbing/28010d1262647997-cabin-bathroom-vent-drain-layout-wye.jpg https://www.askmehelpdesk.com/attachments/plumbing/28011d1262647997-cabin-bathroom-vent-drain-layout-pvc-sanitary-tee.jpg https://www.askmehelpdesk.com/attachments/plumbing/28012d1262647997-cabin-bathroom-vent-drain-layout-5e58a452-46de-48f1-87ce-f63381fe8b8f_300.jpg https://www.askmehelpdesk.com/attachments/plumbing/28013d1262648014-cabin-bathroom-vent-drain-layout-dco.jpg