I am battling installing a new shower and with the layout the trap fall along side a joist (tight) and the main 3″ drain is on the other side.
I will have a cleaner install without hacking the joist up if I install the trap one side of the joist, but connect to the shower pan on the other side.
In other words, Whats the distance I can travel on a waste discharge before I hit a trap? I am only talking 1′-2′ hortzonially here, I am sure I am OK here, just want to check.
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Replies
If I recall my plumber friends, you can go a foot or so before the trap. If you are talking just on the other side of a joist, this should be no issue. Some of the other guys can chime in to confirm this (or not!). Maybe I'm confused on distance between the trap and the vent. Now that I think about it, I'd think there may be no issues w/ the trap being a ways from the drain. Let the other guys correct me.
I am on your side...
Clewless,I am thinking along your same lines.
I just don't want to be classified with those bad plumbers that hack at floor joist with a chainsaw!!
If I've got the picture right, you would drop straight down from the shower drain connection into the trap. The outlet of the trap would be in the horizontal, and would pass thru the joist to connect to the 3" line by means of a wye fitting (a 3 x 2 wye).
If that's correct, the length of the trap arm could be as much as 5 feet, or even 8 feet, depending on what code you're on.
If that 3" line drains a toilet that's located upstream of your shower drain, the shower trap will be subject to possible siphonage if the 3" line runs full. To protect against that, it's best to have a vent on trap arm that serves the shower.
No, the drop straight down from the shower would take a 90 then travel less than 1' (through the joist) before it hits the trap.
Then hits into a 4" that is also within 1' , the 4" is the vented upwards.
Yes there will be a 3" that handles a toilet approx. 3' upstream of this shower. I have a lot going on in a small area, all of this is within 3-4' of the main stack/vent.
Never thought of the flush siphoning out the shower trap. I can try to fit in a small vent in the hortz run of the shower.
Vent
You will still need to get a vent after the trap either on or before the main waste line. The evnt needs to start up within three feet of the trap.
"The vent needs to start up
"The vent needs to start up within three feet of the trap."
Maybe your jurisdiction has stricter rules, but the UPC allows a 2" trap arm to be 5 feet long, and the IPC allows 8 feet.
You will be making what is called a running trap--that is, the trap will have both its inlet and outlet in the horizontal, and at about the same level. This tends to reduce the velocity of the flow thru the trap compared to the usual configuration where the inlet is in the vertical. Running traps lose some of the ability to be self-scouring, but in the case of a shower, this is not too much of a problem compared to a kitchen sink with its grease and food scraps.
As for the connection to the 4" stack, do you mean that the trap arm of the shower ties into a vertical portion of the 4" stack that continues upward as a vent and drain for other fixtures?--If so, that's good. You shouldn't need to worry about any additional venting of the 2" shower trap arm, because 4" is so large. There's no way that even the drainage from the toilet could fill the 4" vertical line enough to start a siphon that would affect the trap of the shower.
4" stack
Yes, the hortz, 2" trap for the shower arm dumps into a 3" wyee (that picks up the toliet) then into the 4" vert stack that is the vertical vent. All with in a matter of no more than 18" - 24" This is the last fixture that dumps into this 4" stack.
That's what I was thinking that it would take a bunch of toilets flushing at the same time to comepletey charge a 4" line.
But if I have to vent it I could fire up the chain saw!!!
We are talking a lot happening in a small area.
I get the picture now. It would be better if your 2" line could tie into the 4" stack rather than into the 3" toilet drain. This is because the 3" is more likely to fill completely than the 4".
If you just can't tie in the 2" anywhere but into the 3" horizontal line, roll the 2" branch of the 3 x 2 wye as high as possible so that it's above the flow line of the 3" as much as possible and in the top half of the 3" line where it will have more access to air. This will greatly reduce the chance for siphoning or burping of the 2" trap seal.