New Drains/Vents routing. . .

TALDEMay 4, 2013

I have this posted on a few forums. . .here goes!

Hello All!

I am hoping for a quick answer from the experts to a drain/vent issue in a bathroom renovation currently in progress. Please see the pic for more details.

The bathroom originally had a small shower stall and one sink. I'd like to install a double shower and double sink which will require moving the drains and vent pipes (ALL pvc). I think I have this right. . .

As you can see from my crude mock up, the new shower drain (2 inch) will be located as pictured and run parallel with the floor joists and then through one floor joist and into the soil stack (connecting with a furnco fitting).

[B]1. Are two 45s better than a 90 degree fitting to make the turn?[/B]

[B]2. Since the drain is more than 5 feet from the stack, I understand that I need to vent it. . .correct? [/B]

My plan was to use a tee from the drain (as pictured), use a 90 to take it up through the (yet to be built) side shower wall, and then use another 90 to take it back over to the existing roof vent (which lies roughly above the new drain as I have pictured).

[B]3. As I understand it, a 1.5 inch vent is required. . .or can 1.25 inch (what the original was) be used?

4. Also, is it ok that the horizontal portion coming from the drain through the joists be in two sections (as I don't believe I could put that in as one solid piece)?[/B]

For the sink drains/vents, I have a few concerns/questions. I plan to install my own vanity top and use two vessel sinks.

The drain/vent pipes for the original sink was 1.25 inch. It's my understanding that with two sinks, 1.5 inch is required (recommended?)? Since the drain pipe for the original sink entering the stack is obviously 1.25 inches. . .

5. Can 1.25 inch be used to drain the two sinks or does it need to be 1.5 inch? If I use 1.5 inch, I would still have to reduce it to 1.25 inch to enter the stack, so. . .:confused:

To the right of the pic, the X on the wall marks the center of the vanity placement. I was planning to "T" off the sink P traps and use one pipe for the drain and one pipe for the vent. The vent would go up the wall, 90 off, then tie into the vent from the shower vent, and then tie in to the roof vent. I plan on building a 2x3 wall on the existing wall since 1. that is a bedroom wall, and 2. the duct work runs right under that existing plate, making it difficult to place the 90 degree turn (in the existing wall) to go to the stack. So. . .

[B]6. Is it better to run the sink drain as pictured "above," which would entail progressively notching the top of the joists (2x10), come over the duct, notch the next joist, use a 45, then hopefully be low enough to drill [U]through[/U] the remaining joists to continue the downward slope to the stack. It looks like I would be able to do it with two pieces (piece from drain--->45--->piece to stack). [/B]

[B]7. Or would it be better to move everything to the "right" near the right side sink (sort of out of frame in the pic) and run the drain "straight" across (notched and through) the joists (bottom blue line)?[/B]

I hope that is clear and anticipate some advice from the experts! Thanks in advance!


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