Re: Trap arms
Posted by Jeff S. on February 17, 19100 at 20:13:40:
In response to Re: Trap arms
: : Can a trap arm only run horizontally, or can the same trap arm contain both horizontal and vertical runs before the point where the vent connects? I'm trying to plumb my kithen sink DWV without using an island vent. Although it is not in an island, the sink is against an exterior wall with a window above and I can't run the trap arm through the studs because it would violate the code for boring load bearing studs. So I want to run the trap arm into the exterior wall, down into the crawl space and then over horizontally to pick up a vent in the same exterior wall just to the side of the window. This is new construction. Is what I'm describing permitted? Thank you very much.

: Jeff, you have to plumb the kit sink according to the code that applies to your area. I have not in my 38 yrs of plumbing never been prohibeted to drill the studs out under the window for the kit sink horizontal trap arm. Do some checking on that. Tell me what code applies to you and i'll send you a drawing. Dale's Plumbing Service LMP

The building code in my area (CA) is UBC 1997 and also the UPC. The UBC says you can't bore more than 40% of the width of a load bearing stud, so the 1.5" trap arm is too much for a 2x4 wall. It's never done in my area. Either the plumber uses the island vent or leaves the trap arm out of the wall so the ugly thing is visible inside the cabinets. I would do the island vent but I'm a little confused because my foot vent direction would be 90 degrees turned from the waste line direction. The diagram I found on this website shows them going in the same direction. I guess I could use a 90 elbow for the waste line after the point where the foot vent connects to it. Thanks. I hope this is not too confusing.

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