How would you vent & run water in this basement bathroom?

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Old 04-25-20, 07:00 AM
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How would you vent & run water in this basement bathroom?

Homeowner here. Installing a large master bath in my basement. Builders roughed everything in under the slab, and I framed it and ran electrical. Was planning to hire the plumbing, but between the quarantine and plumbing estimates I got, I'm considering doing it myself. I've posted a couple photos and will describe my issues below. Would appreciate advice and how you'd vent and run water to the lavs in this setup. Thanks!

1) Builder put a main HVAC trunk directly above lav 2. I dropped the ceiling to just barely below it while framing, but I hadn't considered plumbing at the time. Trunk extends out several inches on either side of the header, so vents and PEX lines to lav 2 can't come straight down. Either they need to run through the framing on either side or I need to frame a bulkhead on the wall behind the bathroom. That area is like an entryway or sitting room with entrances to the master bedroom, bath, and a closet.

2) Builders left a capped 1.5" vent above lav 1 and another on the far side of the basement about 25 feet away -- perhaps for lav 2. It's near the ejector pit, but that already has its own capped vent left on the wall right next to the waste line. Can both lavs (and by extension, the whole bathroom -- two lavs, toilet, and separate tub and shower drains) be vented by the line above lav 1? Either way, how would you deal with that stupid HVAC trunk above lav 2? Can a 1.5" vent line realistically be run through the framing above the doorway there to serve lav 2...or is a backside bulkhead a better idea?

3) Builder left 3/4" PEX stubs above the toilet and shower, but none above either lav. There are 1/2" lines running in the joists above lav 1, I believe from the laundry to the kitchen on the main floor, but no stubs left. Would you tap into that 1/2" line to supply one or both lavs, or would you tee off one (or both) of the sets of 3/4" stubs that were left elsewhere in the bathroom? And again, given the obstacles around lav 2, how would you run those lines? Parallel to the vent after figuring that out?

Thanks for any advice!
 
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Old 04-25-20, 06:38 PM
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Well, you know you're going to have to get the vent and supply lines connected somehow.

For the vent, you can either drop the ceiling down a few extra inches and run the lav2 vent in the ceiling under the duct. Alternatively, you could build out the wall with 2x6 and run the vent through the studs over the doorway.

It's easier to run the supply lines, but you're going to have to follow a similar path.
 
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Old 04-26-20, 04:38 AM
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tie both sinks to that one vent, Take all water lines from the 3/4 stubs.

Do what you need to to get the piping there.
 
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Old 04-26-20, 07:25 AM
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Bumping for the Sunday crowd. I got some suggestions on other plumbing boards but would love opinions here. If anyone has the patience to actually suggest runs, that would be great. But if it's simpler to just answer a couple direct questions, here's mine:

1) Since I've got 5 fixtures requiring water (cold only to the toilet, obviously), how would you share the four 3/4" stubs I was left (2 hot, 2 cold) by the toilet and shower. I'm thinking share the toilet with the two lavs and share the shower and tub. All 1/2" lines.

2) I got the suggestion of an AAV at lav 2 given the obstacles, but I don't know how everything is tied together under the slab for wet venting. Would an AAV be an issue if that lav is venting other fixtures in the bathroom?
 
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Old 04-26-20, 07:37 AM
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not sure why there are 4 stubs.

Use two 3/4 h\c to all fixtures but shower and tub. ( reduce to 1/2' somewhere along the way.

Use other two stubs for shower and tub and run 3/4 to them as close to fixtures as you can get before reducing to 1/2"

Dont use aav's. You have a vent there so use it.

its not that complicated. Build a chase for the one vent if needed.

Tie both sink vents up in the ceiling with a sanitary tee..
 
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Old 04-26-20, 07:53 AM
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Plus you need better pics so I can see the vent and see the hvac duct
 
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Old 04-26-20, 07:56 AM
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and you dont have to go straight up with vent.. go 3ft above sink rim plane and drill hole right a few studs to get past hvac..
 
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Old 04-26-20, 08:51 AM
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Really appreciate all the replies this morning -- very helpful. I'll attach a few more pictures, so please let me know if you have any other ideas. It was suggested on another forum that I may be able to squeak a 90 turn under the HVAC to vent lav2 over to lav1 if that trunk has any upward play at all, but it doesn't seem like it does. So about 1.75" clearance.

Looks like I'll either be lowering the ceiling or building a little soffit on the backside of the bathroom. Not a huge deal. As you guys mentioned, the other option is run the vent through some studs there, but it's all framed in 2x4 and would require me to go all the way over to almost the end of the doorway given how long the HVAC trunk is. Probably easiest to just deal with the ceiling height. But again, I'm still open to suggestions. Thanks again! Really nice of you to reply!
 
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Old 04-26-20, 10:15 AM
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i need better pics..

You can get that vent on the other side of duct im sure 1 1/2 will fit under it.. If not whats to right of it?

Or come forward over to the other and up and over the duct..

Your not showing what I need to see..

The vent looks up high. this looks like a non issue.

 
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Old 04-26-20, 12:30 PM
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Thanks. Yes, going straight up and venting the lav on the right side of that picture is no issue. It's the lav on the left side I'm not sure how to tie in with about 1.75" of clearance between the header and HVAC. Will a 90 for a 1.5" vent line fit there to enable me to bring that line out in front of the HVAC? Guess I could go buy and and find out :-) Just though it'd be closer to 2" or bigger OD.

If there's a specific angle for a photo that would help you visualize how to tie together the two vents for those lavs, just let me know -- I'm happy to take it. Thanks again!

 
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Old 04-26-20, 01:04 PM
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just make the turn left through stud.. Then right into other wall then up..

 
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Old 04-26-20, 01:05 PM
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I see the wall there.. Run it up next to that other door way...

 
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