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 Between a rock and and floor joist
Author: md9918 (MD)

Hey folks. First time caller, long time listener. Thanks for all the advice.

I'm retrofitting a bathroom into what was was a very small second story bedroom in a 100 year-old brick rowhouse in Baltimore.

Here's my setup:

I've got a 3" stack coming up from the basement terminating in a closet bend, with a 2" branch which will carry water from a bathtub, laundry, and lav. The joists are 3x8 (2.5x7.5 actual, give or take depending on the joist).

The way I see it, I've either got to bore through the joist at a 45 degree angle, which beyond being technically challenging, could potentially compromise the integrity of the joist or use a 3x2 sanitary tee instead of a 3x2 wye and run perpendicularly through the joist.

I have concerns about boring because the 2.5" hole I'd need is the max I can bore through these joists. Boring at an angle lengthens the hole, and I can't seem to find any guidance on the propriety of boring at an angle.

On the other hand, swapping out the 3x2 wye for a santee also requires me to swap out the 2x1.5 wye for a santee to keep everything lined up properly. For what it's worth, the 2009 NPC (which applies here) permits both long sweep and standard elbows for horizontal to horizontal direction changes. While a santee is still against code, it seems to me that its sweep is comparable to that of a standard 90. Is this a situation where I should seek an exception from the inspector?

So, either bore through a 2.5" joist at a 45 degree angle or swap out two wyes for santees. Both options have pros and cons. I'm not thrilled about either. What do you all think?

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 Re: Between a rock and and floor joist
Author: hj (AZ)

If you have room for a san tee, you may also have room for a combo Y-1/8 bend.

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 Re: Between a rock and and floor joist
Author: packy (MA)

i would imagine there are hundreds of thousands of san tees installed this way all across the USA.
other than a possibe snaking problem, i don't think it is the end of civilation as we know it.

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 Re: Between a rock and and floor joist :clap:
Author: md9918 (MD)

Thanks, HJ, I'll pick up a comby and see if it fits. And packy, thanks, I tend to agree. Folks in other forums out there are a little more dogmatic about code violations though (which is why I didn't post this in one of those). Thank you both.

Edited 1 times.

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 Re: Between a rock and and floor joist
Author: sum (FL)

can't see your picture.

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