Two 45s into Soil Stack Double SanTee

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Marchiano

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Due to structural obstacles and the length of the run, I’m forced to do this or make everything lower (below the metal bars). Or perhaps there’s some other way I’m unaware of.
 

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wwhitney

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So what are your 4 connections on the double san-tee? Depending on the application, the offset may or may not be allowed. And likewise, a double wye might be better.

Cheers, Wayne
 

Marchiano

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So what are your 4 connections on the double san-tee? Depending on the application, the offset may or may not be allowed. And likewise, a double wye might be better.

Cheers, Wayne
The left branch is from a bathroom and kitchen sink (bathroom has 1.5” vent through roof), right branch is from a bathroom and laundry room, up is the main 2” vent straight all the way through the roof, down goes to a wye cleanout and 45 to the main sewer line. I tried a double wye but would still have to use multiple angles for that left side.
 

wwhitney

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A couple comments, based on the UPC in force in California:

- If everything is already vented as it comes together at the san-tee, then what you show is allowed. But you don't necessarily need a vent at that location (see below). The double san-tee is hard to snake through (when you want to go down rather than across), but the cleanout just below addresses that concern.

- Each WC needs a 2" vent, so the bathroom vent needs to be 2", not 1.5". So with two bathrooms, you should have at least one 2" dry vent for each one. A 2" dry vent at the lav suffices to wet vent the rest of a bathroom (with a 2" lav drain, which first joins the shower or tub, upsizing to 3" after both a shower and a tub join (if there are both), and WC last).

- The house as a whole needs vents through the roof that are at least as big as a 3" vent. (2) 2" vents is a bit smaller, so you'd need (2) 2" vents plus a 1.5" vent. But the laundry and the kitchen sink will each need a 1.5" vent, so at some elevation you will have (2) 2" vents and (2) 1.5" vents. Depending on how you bring them together, you can either end up with at least (2) 2" and (1) 1.5" roof penetrations, or just (1) 3" roof penetration.

Cheers, Wayne
 

Marchiano

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A couple comments, based on the UPC in force in California:

- If everything is already vented as it comes together at the san-tee, then what you show is allowed. But you don't necessarily need a vent at that location (see below). The double san-tee is hard to snake through (when you want to go down rather than across), but the cleanout just below addresses that concern.

- Each WC needs a 2" vent, so the bathroom vent needs to be 2", not 1.5". So with two bathrooms, you should have at least one 2" dry vent for each one. A 2" dry vent at the lav suffices to wet vent the rest of a bathroom (with a 2" lav drain, which first joins the shower or tub, upsizing to 3" after both a shower and a tub join (if there are both), and WC last).

- The house as a whole needs vents through the roof that are at least as big as a 3" vent. (2) 2" vents is a bit smaller, so you'd need (2) 2" vents plus a 1.5" vent. But the laundry and the kitchen sink will each need a 1.5" vent, so at some elevation you will have (2) 2" vents and (2) 1.5" vents. Depending on how you bring them together, you can either end up with at least (2) 2" and (1) 1.5" roof penetrations, or just (1) 3" roof penetration.

Cheers, Wayne
I really appreciate you taking the time to assist me! If I weren’t to have the vent where the two branches meet, would I just cap the top of the tee with a cleanout (or plug?). Aside from that, I’ll size up the 1.5” vent to 2” and probably size the 2” up to 3”. There’s no way for me to link the left bathroom vent to the vent above the San-Tee since the roof is vaulted in the area between them. I may have oversized the bathroom wet vents at 3” though there are two lavs and both a separate shower and tub in each so maybe not. Thanks again.
 

wwhitney

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On the bathroom wet vents, going downstream from the dry vent, minimum sizes are as follows. (Tub/shower order doesn't matter, and there are different ways to a do a double lav.) 2" dry vent, 2x2x1-1/2x1-1/2" double fixture fitting for the two lavs, 2" lav drain, 2" horizontal wye for the tub (or one inlet is 1-1/2" if you use a 1-1/2" tub trap), 2" tub/lav drain, 3x2x2 wye for the shower, 3" shower/tub/lav drain, 3" wye for the WC, 3" bathroom branch drain.

If you don't need the vent connection at the double san-tee in the picture at the OP, there are a variety of ways to bring the two horizontal 3" branch drains together and connect them to the building drain. As seen from above, the two 3" branch drains are coming in at 3 o'clock and 9 o'clock, say; what angle does the building drain exit at?

Cheers, Wayne
 

Marchiano

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On the bathroom wet vents, going downstream from the dry vent, minimum sizes are as follows. (Tub/shower order doesn't matter, and there are different ways to a do a double lav.) 2" dry vent, 2x2x1-1/2x1-1/2" double fixture fitting for the two lavs, 2" lav drain, 2" horizontal wye for the tub (or one inlet is 1-1/2" if you use a 1-1/2" tub trap), 2" tub/lav drain, 3x2x2 wye for the shower, 3" shower/tub/lav drain, 3" wye for the WC, 3" bathroom branch drain.

If you don't need the vent connection at the double san-tee in the picture at the OP, there are a variety of ways to bring the two horizontal 3" branch drains together and connect them to the building drain. As seen from above, the two 3" branch drains are coming in at 3 o'clock and 9 o'clock, say; what angle does the building drain exit at?

Cheers, Wayne
I think I’m understanding all of that correctly. Maybe I’ll post more info the further along I get.

The building drain exits around 1 o’clock.
 

wwhitney

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With the building drain heading out at 1 o'clock then it's definitely easiest to go vertical between the horizontal branch and the building drain. Simplest would actually be to bring the two horizonal branches to the building drain offset by a couple feet. They would connect via a quarter bend into a wye plus 45. On the upstream one, the wye and 45 can be in the opposite order to provide a cleanout angled up, if that is preferred over a horizontal cleanout. And then if you still need a vent, you can use a san-tee instead of a quarter bend.

Let me know if separating the two branches by a couple feet along the run of the building drain is not an option and I'll think about alternatives to the double san-tee if you don't need a vent takeoff there.

Cheers, Wayne
 
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