Venting a Shower P-Trap

goldenboy · 02-03-2010, 11:53 PM

Hello, new to the forum and hoping you guys and help out. Below you will see two images. The first, titled "Original" was my original plan to vent the p-trap on the shower. However, due to the span of 8 feet and needing 1/4" slope per foot, I didn't have enough room to fit the plumbing in between the 10" floor joists (I would only be able to get about 1" of slope instead of the 2" required).

The second image is my revised plan. Although it doesn't look like I would gain space, I would (the picture isn't to scale). I guess my question is....is there anything wrong with venting the shower side like that? Any other comments on my complete setup? Thanks!

bkeech · 02-04-2010, 09:35 AM

Cant you wet vent? I dont think you need a vent for each p-trap.

goldenboy · 02-04-2010, 10:36 AM

Well, after talking to a plumber and explaining my current situation, he thought the distance between the shower and the tub was to much to vent out of the tub vent.

bkeech · 02-04-2010, 10:47 AM

I dont think it would work as the vent pressure needs to be above the p-trap.

Can you off set the drains in the joist space?

goldenboy · 02-04-2010, 10:56 AM

Depends on what you mean by offset? The problem with the "original plan" is the shower T (the one that goes up to the vent and down to the elow) and the long elbow below it (long because I was told that when you go from horizontal to vertical it must be the "long" elbow) measure 9.5" in height. Being that I only have 10" of space between the floor joists, I can not get the required 2" of slope in that drain.

goldenboy · 02-04-2010, 11:14 AM

Quote:

Originally Posted by bkeech

I dont think it would work as the vent pressure needs to be above the p-trap.

Can you off set the drains in the joist space?

Also, aren't they venting in the same place on each of the plans (both are above the p-trap)? Not sure I see the difference. Thanks.

rudolph58 · 02-04-2010, 12:35 PM

your original plan is the best.use a double or back to back t if the waste is going vertical and a double or back to back y if going horizontal.
(drain out)

goldenboy · 02-04-2010, 02:21 PM

Can't do the original plan due to not having enough room for the slope. I think I have it figured out. Using the revised plan, instead of using the T after the p-trap, I will use a Y and instead of the 90 degree elbow on the vent I will use a 45 from the Y over to the vertical vent which will be a long 90 elbow.

RegeSullivan · 02-04-2010, 05:23 PM

I think a pro (plumber) would go to 1/8" per foot if they had to to make your first plan work. Maybe a plumbing professional could weigh in on this.

Rege

rudolph58 · 02-04-2010, 06:10 PM

where is your vanity or lavatory sink?

rudolph58 · 02-04-2010, 06:10 PM

and the stool?

NHMaster · 02-04-2010, 06:12 PM

the shower vent, the one on the right side. Where it runs horizontal. You can't do that. Vents must rise vertical until they are 6" above the flood level rim of the highest fixture served. In this case that would be 6" above top of the tub, or 6" above the lave if the drains tie together.

goldenboy · 02-04-2010, 11:13 PM

Sink and stool are on the opposite wall hooked into a different line.

You sure about the venting will not work in the revised plan? Asked a plumber today and he said it would work. If I can't do it this way, what do you suggest?

{EDIT} Saw it in the code...you are right. Sucks that I glued everything together today according to the "revised plan" before I saw your post. Guess I will have to restart it. Let me know if anyone can come up with how to do this right.

Alan · 02-05-2010, 02:08 AM

Cannot use a TEE to tie drains together. Must be a wye or fittings of equivalent sweep.

2" drain coming up :put a 2" wye on the drain and put a 2" street code 90 in the wye branch to keep shower side low.

Your shower side is going to be similar to your tub side, but slightly different. How many degrees are we allowed on a trap arm? 90* is the correct answer.

When you get to your shower side, instead of using a LT 1/4 bend, put a street 45 in the bottom of a 2x1-1/2x2 sanitary tee, and turn the tee so that it will be perpendicular to your drain line. You will also need a 1-1/2 street 45 in the top outlet to straighten yourself back to level and get up the wall. Now run your trap arm from the sanitary tee to whatever distance your shower drain is, and use a long turn 90* to get back to the drain. I could draw this in a second but I don't have a scanner, so I hope that makes sense. It should fit if you do it that way. You may have to drill a larger hole in the bottom of the wall so that your 1-1/2" 45 will go partially into it. Also to do this you won't want to run your drain straight at center of your shower drain. You will want to be 6" to 12" to either side of it to make room for the 90* offset back to it.

Alan · 02-05-2010, 02:12 AM

Are you familiar with isometric drawings? That would be the easiest to do and i could sketch one out real quick on paint probably. It would be ugly but it might make more sense that way....

I'm also confused to where your drain outlet is coming from. It's just floating in air in your drawing. Do you have a picture to show where this is going? It might make it easier.