Single vanity, toilet, bathtub shower aligned on 9′ long, 8; high 2X6 wet wall, which also serves as a plywood sheathed shear wall. 3″ PVC drains toilet, 2″ PVC into the 3″ for vanity and BTSh drains.
SE MN climate
I’ll vent the toilet with 3″ straight up through the top double plate…venting the other two fixtures with 2″into the 3″ (joining the 3″ above fixture flood lines, of course).
Question is, since this is a non-load bearing wall, (trusses above) but IS a shear wall, which is better:
Cut holes for the 2″ through the top plate and join the 3″ vent up in the attic, or put 90 degree vent elbows in and cut holes through the studs to join the 3″ BELOW the top plates?
Framing sub (who engineered the shear wall) says through the plates. That’s three holes through the plate versus one hole through the plate and several through the studs.
I may have answered my own questions, but do you think it makes a difference? In other words, generally, do you join vents in the attic or below the plates?
Replies
I can't answer the question about the shear wall, but the only requirement for the vents are they they must start up within 3' of the fixture drain and be above the flood plane. The attic is definately above the flood plane:-)
Dave
I'd say one hole through the plate..less fire stopping caulk. Among other ideas..easier to drill a few smaller holes than larger in a double..shearwall is still connected to almost solid top and bottom plates..just seems to me to make sense..
Just to nitpick, you can vent the whole thing with 2", starting from the toilet with 2" and bringing up 1-1/2" for both the bath/shower and the lav. It's usually a bit easier to bring everything together in the attic because going laterally thru more than one stud means bending the pipe and forcing it in there (can be done but it encourages you to drill overly large holes). I'm not an engineer but I bet the strength of the wall is minimally affected by either and that keeping the holes (pipes) smaller is an advantage.
Thanks for the response...I considered 2", but will also be joining a half bath, washing machine drain, and kitchen sink into one vent through the roof. DW doesn't want vents on front of house roof, and I want to mimimize # of roof penetrations. So I'm starting out with 3" in master bath, branch vents will be 2" tied in along the way, all runs in the attic space.