Need help with DWV and venting for new bathroom

Users who are viewing this thread

jerryf

New Member
Messages
3
Reaction score
0
Points
1
Location
NC
Thanks for this forum! Lots of great advice. Hoping you can help with some questions about a new bathroom. We converted an old playroom (24x24) in to a new downstairs master and bathroom. We completed the bedroom, closets, and everything except the bathroom before the pandemic hit. Not finally getting to the bathroom. Attaching a couple diagrams to help convey what I'm dealing with. Essentially I'm trying to devise a solution to wet vent and use air admittance valve(s) to adequately vent this bathroom. Hard part is most of the walls are finished except the 3 walls around where the shower is planned and they are open on the inside. Attic above entire area and crawlspace below. I think I can get a 2" vent up through the roof for the toilet however the bathtub, sink and shower will all be upstream of the toilet.

The order would be starting with the tub, then sink, then shower then toilet, and then tying in to an existing 2" drain line that I'll be replacing with 3". Out kitchen sink and washing machine are the only other fixtures further downstream on the existing 2" drain. Starting with the tub and sink I was thinking to go with 2"pipe. So tub with 1.5" trap then going in to 2" and same for sink. Continuing 2" through the shower and then increasing to 3" when getting to the toilet. Question is location(s) and quantity of AAV required? I'm thinking one under sink might be sufficient with increased pipe size. Would I also need one in crawlspace at the tub trap? Since most of the walls are closed no way I could properly vent all to atmosphere.

There is an existing AAV in the crawlspace between kitchen sink and washing machine. After this bathroom is complete I'll also be moving the washing machine to a different location on a different line.

Any of your expert opinions and advice much appreciated! Feel free to ask any questions as I'm sure there is important info I've missed. I've spent many hours on this forum determining where I will need wye's vs sanitary tees etc. etc. Thanks!!!!

p.s. - sorry for the horrendous drawing ability and handwriting... ; )
 

Attachments

  • bathroom layout.jpg
    bathroom layout.jpg
    35.2 KB · Views: 73
  • dwv.jpg
    dwv.jpg
    32.6 KB · Views: 71

John Gayewski

In the Trades
Messages
2,168
Reaction score
546
Points
113
Location
Iowa
The problem I would guess is your vent location is more than 6 feet from one or more of the fixtur traps. The tub and sink mainly look like there would te more than six feet of pipe to the vertical vent in this case.
 

jerryf

New Member
Messages
3
Reaction score
0
Points
1
Location
NC
That’s correct and the reason for the question. Most of the walls are finished and there is no way to vent those normally. What I’m asking is how to use wet venting along with air admittance valves to accomplish this. Thanks!
 

wwhitney

Well-Known Member
Messages
5,230
Reaction score
1,316
Points
113
Location
Berkeley, CA
A single AAV under the lav can wet vent the bathroom group under the IPC. I'd be inclined use a 2" trap for the tub. Then the tub drain has to connect to the lav drain before the tub trap arm falls more than 2". I.e. within 8' if the fall is exactly the minimum of 1/4" per foot.

Likewise, the shower has to connect to the tub/lav before the shower trap arm falls more than 2". Your drawing makes it look like you have a vertical jog downward at the shower to tub/lav connection, that is not allowed and you need a horizontal wye or combo.

The WC is not subject to the fall restriction, so the drawing is OK on that aspect.

Then the kitchen sink needs a vent at the elevation of the trap. If there's no atmospheric vent in the wall behind the kitchen sink, it needs an AAV under the sink. An AAV in the crawl space does not do the job.

Likewise the clothes washer standpipe needs a vent at the elevation of the trap. Same options as the kitchen sink; an AAV in the crawl space doesn't help unless the washer standpipe trap is in the crawl space. And then the AAV needs to be on the sandpipe trap arm before that trap arm joins another drain or falls more than 2".

Lastly, the IPC requires that when the washer standpipe drain joins another drain, the joint (branch) drain is at least 3". Something to bear in mind when you move the washer.

Cheers, Wayne
 

jerryf

New Member
Messages
3
Reaction score
0
Points
1
Location
NC
A single AAV under the lav can wet vent the bathroom group under the IPC. I'd be inclined use a 2" trap for the tub. Then the tub drain has to connect to the lav drain before the tub trap arm falls more than 2". I.e. within 8' if the fall is exactly the minimum of 1/4" per foot.

Likewise, the shower has to connect to the tub/lav before the shower trap arm falls more than 2". Your drawing makes it look like you have a vertical jog downward at the shower to tub/lav connection, that is not allowed and you need a horizontal wye or combo.

The WC is not subject to the fall restriction, so the drawing is OK on that aspect.

Then the kitchen sink needs a vent at the elevation of the trap. If there's no atmospheric vent in the wall behind the kitchen sink, it needs an AAV under the sink. An AAV in the crawl space does not do the job.

Likewise the clothes washer standpipe needs a vent at the elevation of the trap. Same options as the kitchen sink; an AAV in the crawl space doesn't help unless the washer standpipe trap is in the crawl space. And then the AAV needs to be on the sandpipe trap arm before that trap arm joins another drain or falls more than 2".

Lastly, the IPC requires that when the washer standpipe drain joins another drain, the joint (branch) drain is at least 3". Something to bear in mind when you move the washer.

Cheers, Wayne
Thanks Wayne! Great information. No vertical jog at the shower connection. That was my (bad) attempt at drawing the trap there. Was planning to connect with a wye/45 or combo. My drawing was more conceptual and wasn't showing the specific connections. That's good to know on the washer standpipe as I didn't realize that! It currently feeds in to a 2" drain. House was built in the 70's though. Thanks!
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks