Feedback on a two bathroom drain line

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ronstory

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All--

Long time reader, first time poster. The expert on this site have been amazing and helpful. I'm doing a remodel on 2 floor ranch with a daylight basement. The floor joists are only 2x10 so I have limited drop and have planned for a 4" drop for 15 feet. What I have is two baths that are across the hall from each other the drains will be 3" ABS and drop into an existing 3" vertical stack that has a clean-out in the basement before it heads under the slab.

I think I have the design correct, with a left WC is wet vented with a fixture tee with 1.5" side ports for the lavs and 2" drain and 2" vent going up and connects to the 3" line at 45 deg and within 5ft of the toilet. The 3" drain goes down the left side of the 16" wide joist bay.

The second bathroom just has a WC and 1.5" vent connected with the 3x3x1.5 sanitee also as a 45 degs in order to line it up with the wall for the vent.

I would appreciate any feedback on the below primitive diagram and do I need a clean out on the first bathroom toilet? I'm happy to pull a toilet if it's a serious clog, that's easy. Also, I *really* don't want add a clean out since that end of the 3" line will be as high up the joist bay as a can get it... and room below is a finished room. There will be no way to open the clean out without a mess below.

All feedback is welcome. :)

Thanks,
Ron


Upstair_baths_DWV.jpg
 

wwhitney

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If I understand your isometric correctly, the only vertical pipes are the two lines labeled vent at the top, and the 3" vertical stack (and I guess just below each closet flange); everything else is horizontal.

From the right hand WC closet flange to the upright 3x3x2 combo (what you are called a long sweep at 45; that combo could be rolled 45 degrees from upright if necessary, with a 45 above it to have a plumb inlet), the distance measured along the 3" drain is limited to 6'. Otherwise, your double lavs wet venting the right WC look good. You should use a 2x2x1.5x1.5 double fixture fitting where the lav trap arms join and connect to the 2" vent above and the 2" drain below; a cleanout in the 2" drain below the double fixture fitting is desirable, as getting a snake coming into one side of the double fixture fitting to exit the bottom may be difficult.

On the lefthand WC, I understand you are dry venting it, and only the two WCs and two lavs are connected to the top of the 3" vertical stack? Then your dry vent for the WC needs to be 2", not 1.5", and it needs to come off with an upright 3x3x2 combo, not a san-tee on its back. Again the combo can have the side entry plumb, or you can roll it up to 45 degrees if necessary, with another 45 for the dry vent to go plumb.

Cheers, Wayne
 

ronstory

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Wayne, thank-you for your wisdom. :) Yes the only vertical pipes are the 2" wet vent and 1.5" dry vent... and the drop off in the existing 3" stack thru a medium 90 deg elbow.

The 2" wet vent off the lavs and it is a 2x2x1.5x1.5 double fixture fitting and the distance from the right WC is 5 feet so I should be good. I'm not sure about where to add the cleanout since there will be 60" dual sink vanity and the may not have access to center drain. Normally that size of vanity has drawers in the middle so I guess I could pull a drawer out to access.

On the left WC it's tight in the joist bay. So my plan was to have the right WC/Lavs 3" keep to one side of the bay and have a separate 3" for the right WC and they would run in parallel for ~ 2.5 feet and then merge via a wye just before it connect to medium elbow and drops into the 3" stack. On the short drain line for the left WC it would have a 1.5" dry vent via a sanitee rolled to 45 degs since that would easier to get over and line up with the wall.

Since the right WC has the 2" wet vent and the short drain for the left WC (just before the wye) is just for a single WC (3 DFUs) I thought that 1.5" vent could support up to 8 DFUs? Or is it special since it's WC? I'm in Washington state so we are UPC.

Thanks,
Ron
 

wwhitney

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The 2" wet vent off the lavs and it is a 2x2x1.5x1.5 double fixture fitting and the distance from the right WC is 5 feet
Your diagram shows the horizontal distance as 5', but the 6' limit is measured along the pipe, so it includes the vertical drop from the closet flange to the closet bend. And I guess the length should also include the portion of the combo fitting itself that is upstream of the 2" side inlet.

On the left WC it's tight in the joist bay. So my plan was to have the right WC/Lavs 3" keep to one side of the bay and have a separate 3" for the right WC and they would run in parallel for ~ 2.5 feet and then merge via a wye just before it connect to medium elbow and drops into the 3" stack. On the short drain line for the left WC it would have a 1.5" dry vent via a sanitee rolled to 45 degs since that would easier to get over and line up with the wall.
WCs require a 2" vent, see Footnote 3 on Table 703.2's entry for a 1-1/2" vent:


And you can't use a san-tee on its back, it must be a wye or a combo (with the barrel horizontal). A combo with the side entry between 0 and 45 degrees from straight up is simplest, but a wye rolled 0 to 45 degrees from the branch being upright-most may be more compact.

Note that the branch inlet on a wye rolled 45 degrees is actually at an elevation of 30 degrees, so you'd need to hit a 60 degree bend to turn the vent straight up. That short section of vent at 30 degrees above horizontal is a slight cheat (it should be 45 degrees minimum), but seems to be commonly accepted. Particularly if there's no other way to make things fit.

Cheers, Wayne
 

ronstory

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Got it, need to measure the drain pipe path to make sure it's below 6 ft.

Thanks for the pointer on being able to have some flexibility on the angle off vertical for the right Lav inlet. I'm using a 3x3x2 long sweep for the wet vent on the right WC/Lavs into the 3" horizontal drain and will try and keep it as close as vertical as possible and still get it into the wall.

Ahh, got tripped up by a footnote. So a 2" vent it is... for the left WC. I plan use a 3x3x2 santitee on it's back for the venting since it's a dry vent.

Thanks again!
Ron
 

wwhitney

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I plan use a 3x3x2 santitee on it's back for the venting since it's a dry vent.
For the third time, that is not allowed by the UPC, you must use a drainage fitting.

The reference is the last sentence of UPC 905.3: " Vents less than 6 inches (152 mm) above the flood-level rim of the fixture shall be installed with approved drainage fittings, material, and grade to the drain."


Cheers, Wayne
 

ronstory

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All--

Just to follow up, Wayne's advice was spot on and just passed the rough-in inspection with flying colors.

Wayne--

THANK-YOU! If you ever get to Gig Harbor... I owe you a beverage or two.

Thanks,
Ron
 
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