Can you join 2 p-trap arms (horizontally) before the vent?

[kmuddzy]

Hi. I searched on here but I didn't find my answer. I did find that you cannot have a vertical fitting in the p-trap arm and you can only have a 90 degree maximum horizontal direction change in total.

My question:

I have a 2" shower p-trap and a 1.5" tub p-trap. Both arms from those traps are within 5' of a wall I can run drains & vents in. My question is can I run the 1.5" p-trap arm into the 2" p-trap arm using a 2"x1.5" wye before the shower's 2"x1.5" sani-tee drain/vent so that I can share the drain/vent?

Would it make a difference if the tub drain was 2" instead of the 1.5"?

Oh...and if the p-trap is not installed straight (the street elbow is turned) is that turn counted as part of the 90degree max or is it not counted since it is part of the p-trap and not the p-trap arm?

Thanks! Keith

 

[kmuddzy]

drawings of questions

Here area 2 iso dwgs of my question above:

 

[Sponsor]

 

[Hammerlane]

Here area 2 iso dwgs of my question above:

Is the bottom drawing a close up of the top drawing? Why are the two drawings different in respect to the tub/shower plumbing?

 

[kmuddzy]

Is the bottom drawing a close up of the top drawing? Why are the two drawings different in respect to the tub/shower plumbing?

I'm roughing in 2 different bathrooms in an addition we are building. The top picture is of a girls bathroom over existing 2x8 floor joists and the plumbing has to fit within these 2x8 joists. The bottom pic is of a master bathroom over a new 2x12 i-joist floor (much easier to drill/run the plumbing).

 

[hj]

If I were an inspector, I would not approve either installation. I would require the vent at the point where the two drains meet. Someday, you may regret using 1 1/2" pipe for the lavatory drain line, especially with all those turns in the line.

 

[Terry]

You can use a fixture cross on the vertical, with the vent in the center, or if you are horizontal, you will need two vents, which can revent at 42".

Helpful Plumbing Hints for Residential Construction by Bert Polk Plumbing Inspector Lincoln County

 

[kmuddzy]

Thanks HJ and Terry. That is what I needed to know. I am horizontal so I will have to do a separate vent (& then join the vents above 42") on the top drawing. HJ - I will consider changing the lav drain to 2" since I have all of those directional fittings.

Regarding the bottom of the 2 drawings above (Master Bath), I can't find a 2" Double cottage WYE ( Double WYE with side inlet)where I can join the two 2inch drains & vent at the fitting. Do either of you know where I can find one of these? Or, what do you think about this concept in the image below with the double WYE and street elbow (in plan view) since it will be similar to a cottage WYE? If I can't do that then I will have to separate the shower & tub plumbing as shown in the last image and it would be easier if I didn't have to do this. THANKS!

PLAN VIEW (HORIZONTAL PIPES EXCEPT FOR VENT WHICH RUNS VERTICAL)

 

[kmuddzy]

BUMP....any thoughts on the Double WYE with Street 90 Vent?

 

[Hackney plumbing]

BUMP....any thoughts on the Double WYE with Street 90 Vent?

Thats how I would do my plumbing for sure. Long sweep type fitting in the double wye for the vent.

 

[Terry]

My inspectors don't like that.

 

[Hackney plumbing]

My inspectors don't like that.

Understood......Do they give a reason?

 

[jpb123]

Bump....Terry, any reason why this isn't liked?