Venting a Free Standing Tub

[Charley Red]

Bathroom remodel on second story home adding a tub, single sink seven feet away has 2 inch drainage and a dedicated vent to the roof. Thinking of draining tub with 2 inch pipe and tapping into the sink drainage, so basically a wet drain with a seven foot run. Can we do this or do we need to place another vent thru the roof for the tub.The toilet and shower have their separate drains and vents in the room.

 

[JG plumbing]

You'd need to draw the exact way you intend to do this for us to know for sure if what your taking about will work. In general I think yes you should be fine, but there are a lot of specifics left out.

 

[Twowaxhack]

Bathroom remodel on second story home adding a tub, single sink seven feet away has 2 inch drainage and a dedicated vent to the roof. Thinking of draining tub with 2 inch pipe and tapping into the sink drainage, so basically a wet drain with a seven foot run. Can we do this or do we need to place another vent thru the roof for the tub.The toilet and shower have their separate drains and vents in the room.

I’m not sure if it meets your plumbing code but if it’s 7’ a 2” wet vent is good, but be sure to use a 2” ptrap and run it a little shy of 1/4” per ft of fall. It’ll work perfect.

I’ve read that California only allows a 5’ arm on a 2” trap.

 

[JG plumbing]

Wet vents can't be over six feet or go from one story to another. Trap arms and wet vents are different.

 

[Twowaxhack]

Wet vents can't be over six feet or go from one story to another. Trap arms and wet vents are different.

Wet vents have to be at least 2”.

 

[JG plumbing]

Trap arm and vent section is the distinction.

 

[Twowaxhack]

Trap arm and vent section is the distinction.

Exactly, especially where the two intersect.

 

[Charley Red]

Here is a diagram of our options, all vents and pipes are 2 inches. Option A is kind of a long run while option B is very short but taps into the 2 inch vent of the downstairs bathroom.

 

[Charley Red]

Here is diagram. Couldn’t figure out how to attach a picture-sorry.

 

[JG plumbing]

Your shower trap arm is too long. I'm assuming moving the tub can't happen? Why are you running 2" for a tub only?

 

[Charley Red]

Yes option A has a trap arm of the 2 inch pipe approximately seven feet that’s why we were thinking of option B and draining the tub to the adjacent 2 inch vent coming from the downstairs toilet. I thought that increasing pipe diameter on the trap would increase the distance I could be from the vent if using option A.

 

[JG plumbing]

Not really. 2 pipe sizes gives you a combination drain and vent system. The second way you'd need to change the 1st floor toilet vent to 3"pipe.

 

[Twowaxhack]

The Kansas residential code allows for a 2” arm with 1/4” per ft of drop to go 8’ to the vent.


So it works in Kansas.

 

[Twowaxhack]

Yes option A has a trap arm of the 2 inch pipe approximately seven feet that’s why we were thinking of option B and draining the tub to the adjacent 2 inch vent coming from the downstairs toilet. I thought that increasing pipe diameter on the trap would increase the distance I could be from the vent if using option A.

Increasing the bathtub drain to 2” rather than 1.5” will allow a longer distance from the vent.

You are correct.

 

[JG plumbing]

When it comes down to it we are talking engineering standards. In California this doesn't comply. Other places have worse standards.

If i were you and I was worried about it I would call and ask what they will accept.