Venting shower and separate tub.

[Dam1an]

Hi, please have patience with me, 1st post, diy'r. Located in NJ.

I'm remodeling my master bath. My question is venting and combining 2" drains after individual vents for shower and stand alone bath.
Also am I required to have individual vents?

I've attached a few photos, is this allowed?
I am under the impression that I can't have vertical venting past 6" above highest flood level.

So I came up with the plan in the pictures.
Also, can I combine the two 2 inch drains past venting?

Thank you all so much.
Damian

 

[wwhitney]

Not following your description or drawings very well, but some general points. This is assuming that your shower and your tub are being handled independently of everything else (lav and WC).

The tub drain could be 1-1/2", but you are showing 2", which is often considered better. That would mean you need a 2" tub trap, which on the inlet side would have to adapt to typical 1-1/2" tub waste and overflow.

Your plumbing code allows an 8' trap arm, the distance from the trap to the vent takeoff. http://epubs.iapmo.org/NSPC/NJ2018/#p=188 The general rules are that the trap arm has to slope at least 1/4" per foot, and that its total fall before the vent takeoff may not exceed one pipe diameter (2" in your case). So to get a full 8' length you'd need perfect slope of exactly 1/4" per foot.

To get to your questions, once the two drains have each had their vent takeoffs, the drains can be combined, immediately if desired And the vents themselves can be combined at any point at least 6" above the flood rim level of both fixtures (in this case controlled by the tub rim height). The pipe mockup you show is a fine way to connect the vents. The vents only have to 1-1/2", not sure what size is in your picture.

Cheers, Wayne

 

[Sponsor]

 

[Dam1an]

Not following your description or drawings very well, but some general points. This is assuming that your shower and your tub are being handled independently of everything else (lav and WC).

The tub drain could be 1-1/2", but you are showing 2", which is often considered better. That would mean you need a 2" tub trap, which on the inlet side would have to adapt to typical 1-1/2" tub waste and overflow.

Your plumbing code allows an 8' trap arm, the distance from the trap to the vent takeoff. http://epubs.iapmo.org/NSPC/NJ2018/#p=188 The general rules are that the trap arm has to slope at least 1/4" per foot, and that its total fall before the vent takeoff may not exceed one pipe diameter (2" in your case). So to get a full 8' length you'd need perfect slope of exactly 1/4" per foot.

To get to your questions, once the two drains have each had their vent takeoffs, the drains can be combined, immediately if desired And the vents themselves can be combined at any point at least 6" above the flood rim level of both fixtures (in this case controlled by the tub rim height). The pipe mockup you show is a fine way to connect the vents. The vents only have to 1-1/2", not sure what size is in your picture.

Cheers, Wayne

Thanks Wayne for the in depth explanation....btw i'm no artist, lol. another forum mentioned possible introduction of a vertical "cross". this would allow for 1 vent 2 fixtures. but I was under the impression every trap must have its own vent.

 

[wwhitney]

In the area of the vent takeoff(s), how do you want the combined drain to exit that location, horizontally or vertically? If vertically, using a double fixture fitting to get a single vent takeoff would be an option, not sure if it's a good one. If horizontally, it's not an option.

One other option for a single vent takeoff would be to use one dry vented fixture to wet vent the other fixture. That should be an allowed horizontal wet vent, although I didn't parse the NSPC wording to confirm that.

Cheers, Wayne

 

[Dam1an]

In the area of the vent takeoff(s), how do you want the combined drain to exit that location, horizontally or vertically? If vertically, using a double fixture fitting to get a single vent takeoff would be an option, not sure if it's a good one. If horizontally, it's not an option.

One other option for a single vent takeoff would be to use one dry vented fixture to wet vent the other fixture. That should be an allowed horizontal wet vent, although I didn't parse the NSPC wording to confirm that.

Cheers, Wayne

Horizontally unfortunately.