Mudroom/Laundry room venting question


Old 01-06-14, 04:11 PM
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Mudroom/Laundry room venting question

I'm in the process of moving my washer/dryer from the basement to the first floor. My initial design for DWV doesn't look like it will work because for some reason there are a few extra studs. The plumbing shown is on an exterior wall.

Here was what I had hoped I could do, however, since this is a load bearing wall, I cannot bore 2.5" holes through the 2x4s:

Here are the two options I came up with. Option 1 - both fixtures share a 2" vent which originates from the drain pipe below the floor - no studs are harmed here, but I don't think this is a properly vented configuration.

In this scenario, I would probably squeeze the vent in where the outlet is so I don't have to bore through any of the 2x4s, but will the sink vent properly? The two fixtures are roughly 3' apart

Option 2 - likely a better venting scenario for the sink, and I can use 1.5" pipe to get it through the 2x4s without compromising them but there are 5 studs to bore thru... Once again, I would move vent to where outlet is to avoid boring 2.5" holes thru load bearing studs:

Option 2 is a dirty arm as I understand it (or a re-vent)? I'm not sure why those two extra studs are there otherwise the original design would have likely been doable since I would be boring through the jack stud and the king studs are doubled up. Since it's not clear what role they play I'm not sure they should be touched.

Any input is greatly appreciated!
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Old 01-06-14, 06:02 PM
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First off, you can use a 1.5" vent for both fixtures.

Depending on your sink base, can you shift the sink stub out to the left a few stud bays? Then you'll just run the trap arm inside the sink base. May help a bit.

Drawing #1 and #3 are valid. Drawing 2 ends up with an un-vented sink. You could use #2 if you use an AAV under the sink - if it's allowed in your locale.

Good luck,
Old 01-07-14, 12:05 PM
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Thanks for the reply... That is what I figured. My problem is that even 1.5" vent is too large to fit through a 2x4 unless I sister them up. I think I will do that with the two 2x4s in between the 16" OC studs. That should do it
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