Raising Drain Pipe

[Chris Tjoumas]

Hi,

We recently had a fire in our house and are finally back in and finishing up a few leftover things we didn't have the restoration company do. My wife had bought a vanity a number of months ago which has a large opening in the back where the drain pipe would go, but of course the drain pipe in my bathroom is set just below that so it hits right into the cross piece of wood that runs between each side. I could drill a hole to pass the pipe through, but the trap would extend below the shelf and I'd have to cut a hole in the shelf to allow for the trap to fit. Definitely not ideal...

I've attached a picture of the bathroom when it was down to studs and that drain pipe is about 16" from the floor. Could I redo the pipe right where it comes into the bathroom and have it go up about 4" or so using 45 degree elbows to get the rise just right? I would think that's not an issue, but not sure what might be required based on how it's vented.

Thanks!

Chris

 

[wwhitney]

No, that won't work. The drop from the trap outlet to that san-tee in the side wall is limited to one pipe diameter. Otherwise the trap might siphon. So you can't have the trap arm drop down in that stud bay right behind the vanity.

You'd need to raise the san-tee in the side wall and redrill the corner studs. Easier to get a different vanity or modify your vanity.

Cheers, Wayne

 

[Sponsor]

 

[Jeff H Young]

you can raise the san tee and re drill the wood the corner 90 might be a challenge though. offsetting the trap arm then adding a aav Might be plausable neither option that fun. shear wall one stud not a structural guy but wouldnt be too worried

 

[Tuttles Revenge]

Cut in a new san tee into the vertical. Remove a section of the stud on the partition wall to access the hidden spot. Install new pipe at desired height. Repair stud as needed.

 

[WorthFlorida]

Another option; Depending on the base cabinet design, the drain can go out the right side of it instead of the rear. Cut in a new san tee 90 degrees counter clock wise. Use Furnco's couplings or cement to make the connection on the vertical.

 

[Jeff H Young]

3 say raise the santee vs 1 says turn santee the three win LOL . its all preferance I still think you can offset trap arm and add a AAV easy but I dont like AAV but people seem to love them now a days

 

[Chris Tjoumas]

No, that won't work. The drop from the trap outlet to that san-tee in the side wall is limited to one pipe diameter. Otherwise the trap might siphon. So you can't have the trap arm drop down in that stud bay right behind the vanity.

You'd need to raise the san-tee in the side wall and redrill the corner studs. Easier to get a different vanity or modify your vanity.

Cheers, Wayne

Thanks for the replies, everyone! It sounds like I will just modify the vanity But, I did want to ask what you meant about the san-tee being limited to one pipe diameter... in the stud bay behind where the vanity will go, how is adding a 45 degree coupling changing the diameter? I would think it's just coupling it to extend it up and the same pipe diameter is still running through to the trap. I completely trust what you're saying, just trying to understand it. Thanks!

 

[WorthFlorida]

Thanks for the replies, everyone! It sounds like I will just modify the vanity But, I did want to ask what you meant about the san-tee being limited to one pipe diameter... in the stud bay behind where the vanity will go, how is adding a 45 degree coupling changing the diameter? I would think it's just coupling it to extend it up and the same pipe diameter is still running through to the trap. I completely trust what you're saying, just trying to understand it. Thanks!

I believe Wayne was referring to the trap arm length.

What is the minimum trap arm length?

www.howtolookatahouse.com

 

[wwhitney]

Thanks for the replies, everyone! It sounds like I will just modify the vanity But, I did want to ask what you meant about the san-tee being limited to one pipe diameter...

What I said was the drop (fall in elevation) between the trap outlet and the san-tee is limited to one pipe diameter. So for a 1-1/2" trap, it is limited to 1-1/2" of fall. Which means you can't put in two 45s to get extra fall between a higher trap and the current san-tee.

Cheers, Wayne

 

[Chris Tjoumas]

I believe Wayne was referring to the trap arm length.

What is the minimum trap arm length?

www.howtolookatahouse.com

Just to be clear, I wasn't going to

What I said was the drop (fall in elevation) between the trap outlet and the san-tee is limited to one pipe diameter. So for a 1-1/2" trap, it is limited to 1-1/2" of fall. Which means you can't put in two 45s to get extra fall between a higher trap and the current san-tee.

Cheers, Wayne

Ok, makes sense - I was thinking of doing that, so glad I asked. My thought was doing what I have in this terribly annotated image. Sounds like that's a no no, so I'll just see if I can return this vanity or at least use it in another bathroom down the road and get something else to fit this bathroom.

Thanks, everyone!

 

[Jeff H Young]

actually you can throw a 45 on trap arm near the 90 only thing is you would need to revent it by a aav under sink . its a valid fix just a preferance thing and I guess 13 or 16 bucks for the fittiing is something to concider that could be a deal breaker vs drill hole in bottom of cabinet , or spend whatever time and energy material costs for the other plans I think youve got options pretty easy options . just up to you