Can you guys check my DWV layout.

[Pbalmos]

This is a remodel that i am doing on our own home. I am tired of having undersized drain line so i am trying to go up a size on everything. Let me know what you think. I need some help on venting the kitchen island and bar sink. Both are fed off a 4" line. Can i wet vent this or should i use a studor vent or run a 2" dry vent loop like what is traditionally done. My goal is maximum flow with zero clogs ideally.

 

[wwhitney]

Oddly, the definition of bathroom group in the IPC (Florida's plumbing code) does not include a urinal. So by having a urinal connected that way, you will not be able to use wet venting for your bathroom.

I'm not familiar with urinal installations, does a urinal have an integral trap like a water closet, which it intentionally siphons? Or does it have an external trap like a shower? In the latter case the urinal would need a vent connection at the elevation of the trap (or rather, before the fixture drain falls more than one trap diameter). In the former case the urinal could have a vent connection at a lower elevation, like a WC does.

If you keep the urinal drain separate from the shower, WC, and lav (at least until downstream of those fixtures), then you can use horizontal wet venting for those 3 fixtures. If the distance from the shower trap to the wye where the lav joins is less than 8' (and you keep your slope close enough to 1/4" per foot that the total fall does not exceed 2"), then with a 2" shower trap the lav could wet vent the shower. Otherwise you will need a separate vent for the shower, either through the roof or an AAV.

If the urinal may be vented below the floor, then a single dry vent at the bottom of the page, between the shower and urinal, could provide a circuit vent that would suffice for the urinal, shower, and WC. If the urinal requires a separate trap at an elevation above the floor, then that doesn't work.

Chapter 9 Vents: Vents, 2023 FBC - Plumbing, 8th edition | UpCodes

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For the sinks (including possibly the lav, if it is not wet venting anything), a combination waste and vent is one unusual possibility. Otherwise, you'll will have to provide a vent at the elevation of each sink trap, either a pipe through the roof or an AAV.

Chapter 9 Vents: Vents, 2023 FBC - Plumbing, 8th edition | UpCodes

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Cheers, Wayne

 

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[Pbalmos]

Thanks for the reply. The urinal has a separate 2" trap installed below grade like a shower has. I'll try to re lay it out so the urinal ties in below the bathroom group and then dry vent the urinal. Lav sink will have a 3" combination waste vent that i would like to tie into the 3" stack from the washing machine. Do you see any long term draw backs to using a AAV as far as life expectancy.

 

[wwhitney]

Thanks for the reply. The urinal has a separate 2" trap installed below grade like a shower has. I'll try to re lay it out so the urinal ties in below the bathroom group and then dry vent the urinal.

Give the urinal trap location, since you are planning on having a dry vent in the vicinity of the urinal, seems like circuit venting would be a good option. That would let you keep the drain connectivity order shown in the OP.

I have no experience or opinion on AAVs.

Cheers, Wayne

 

[Reach4]

Thanks for the reply. The urinal has a separate 2" trap installed below grade like a shower has.

1002.1Fixture traps. The vertical distance from the fixture outlet to the trap weir shall not exceed 24 inches (610 mm),

I am not sure that this applies. There is also this thing about having some traps under the floor. I did not search out if that applied to urinals.

 

[Pbalmos]

Re did it and added a circuit vent between the last two fixtures which will extend up through the block wall and tie into the other three inch vents for the bathroom lab and the washer in the attic. I think this should work and have all of my fixtures vented. Do you think 2" is ok or should i make them all 3"?

 

[wwhitney]

With a 4" building drain, IPC never requires any vents larger than 2" in warm climates. [In cold climates, vents may be upsized to 3" just before they exit the top of the building envelope to reduce the risk of frost/snow closure.]

However, a dry vent may not be horizontal below the slab; the takeoff has to be vertical, and the vent must stay vertical (at most 45 degree off plumb) until at least 6" above the fixture flood rim level. So you need to adjust your configuration from what is shown on the right side of the P7aHMz.png image. You could bring the upstream most fixture towards the 4" line at a 90 degree angle so it hugs the wall, then you should be able to get your vent takeoff to rise into the wall without going horizontal.

Note that the vent takeoff can be in the drain that is running parallel to the wall, rather than waiting until after the drain turns perpendicular to the wall. But I guess with circuit venting you'd need to have the 4" drain extend upstream all the way to the vent takeoff.

Cheers, Wayne

P.S. I didn't check the rest of the pictures.

 

[Pbalmos]

Wayne,

The urinal trap is located in the corner next to the existing block wall. Its the 2" trap shown in the pictures. I adjusted my layout and i think i can barely squeeze the trap into the block wall if I 45 up as shown in the pictures. Thanks for the help i wasn't aware about the horizontal dry vent not allowed under the slab. I will have to change the layout in one of my other bathrooms.

 

[wwhitney]

The urinal trap is located in the corner next to the existing block wall. Its the 2" trap shown in the pictures. I adjusted my layout and i think i can barely squeeze the trap into the block wall if I 45 up as shown in the pictures.

If you want to get the vent takeoff closer to the wall, you can replace the 4x4x2 combo (which isn't available street) with a street 4x4x2 wye plus street 2" 45. That should move the 4x4x2 wye vent takeoff 3" to 4" closer to the wall, I think. To be verified with the actual fittings in hand.

Cheers, Wayne

 

[Pbalmos]

Would this work if i roll a combo wy 45 then offset into the block wall for the vent. Seems a little cleaner. I think i have enough room i could also do in 3" for better performance if you think its needed.

 

[wwhitney]

Would this work if i roll a combo wy 45 then offset into the block wall for the vent. Seems a little cleaner. I think i have enough room i could also do in 3" for better performance if you think its needed.

See the last paragraph of post 7. To expand on that:

IPC 914.3 on circuit vents says "The entire length of the vent section of the horizontal branch drain shall be sized for the total drainage discharge to the branch," while IPC 914.1 says "The horizontal branch drain shall be classified as a vent from the most downstream fixture drain connection to the most upstream fixture drain connection to the horizontal branch."

In other words, if your minimum size circuit vent/branch drain size is 3", then you would need 3" starting at the outlet of the vent takeoff wye (so you could use a 3x3x2 wye with 3x2 reducer in the straight inlet). If it's 4", you would need 4" starting at the outlet of the vent takeoff. [But in a normal sized residence it's unlikely that anything is required to be 4".]

Cheers, Wayne