4" closet bend or 3" street 90?

[RemodelBob]

I am trying to install a toilet waste line in a 2x10 joist bay. My horizontal run is pretty long (almost 20' fortunately goes into a dropped ceiling area near the end, so I will have enough slope), so I need to keep the 3" pipe tucked up as high as I can near the toilet. I was planning on using a 3" street 90, but my plumbing reference book keeps mentioning a 4" closet bend.

When I look at a 4" closet bend it looks like it would do a much better job of moving the waste, but it is also much deeper than the 3" street 90, which means I am not going to be able to meet slope requirements.

Is the 3" street 90 adequate? or do I need to find an alternate plan?

 

[Gary Swart]

I'm not a pro, but I'm pretty sure the 3" will be fine. Have you planned the vent?

 

[Sponsor]

 

[RemodelBob]

yup, breaking off with a 3x3x2 Y.

 

[Patrick88]

3" is fine for a bathroom. I would use it for that.

 

[Construct30]

yup, breaking off with a 3x3x2 Y.

Straight up or 45 degree or more.

How do you guys make these darn computers make a degree sign?

 

[RemodelBob]

not enough room to go straight up. going 45 degrees.

 

[Construct30]

not enough room to go straight up. going 45 degrees.

That's OK, I take it you can't make a degree sign either.

They must type it first then post it?

 

[hj]

bend

Uses the spigot closet bend. you can cut the riser off at the floor line after the tiling is complete. It will be "shorter" than a 3" street elbow, just be sure to have enough of the spigot below the floor level so the closet collar/flange will slide down to the floor.

 

[Terry]

Like hj, I also use a closet bend for that reason.
The local hardware stores carry an ABS 4x3 spigot closet bend that will take a 4" closet flange.
If I really want to make it tight, I can trim a bit of closet flange hub away to let the flange drop down farther.

 

[BAPlumber]

one option would be to use a 45 degree closet flange and a street 45. that would keep you pretty high.