[mjhaston]

I have an unfinished second floor. The floor joist are 7.25" deep. There is a spot in a back bedroom closet that has a capped drain line that I'm told is where I would tie into. What is the furthest I would be able to run a drain so that I could put a shower, toilet and sink in a new bathroom? I'm thinking a shower about 80" away, but then the toilet and sink would be a 90 degree turn from the shower.

A plumber told me I may need to raise my floor, but others in my neighborhood tell me I don't. I live in an area where all the houses in each neighborhood/section are basically the same.

 

[Colbyt]

Shower and basin probably not a problem. Toilet requires at least a 3" line and you have to 90 that existing 3" line to meet it.

 

[chandler48]

With only 7.25" you won't be able to run very far considering you will need 1/4" per foot drop without using the lower 1/3 of the joists. It will weaken them too much.

 

[Colbyt]

I assumed he was running with the joists. I would not cut a 3.5" hole anywhere in a joist.

 

[mjhaston]

From the spot where I would tie in with the drain, I would run with the joist for about an 80" span. Then I would like to make a 90 degree turn and have a toilet and sink. I'm hoping something like this picture in the url. Maybe I need to put the toilet next to the shower to lessen the span?

So the tie in would be 80" left of the shower in this picture. The joist run perpendicular to the hard wood in the picture.

https://www.finehomebuilding.com/2017/05/10/bathrooms-sloped-ceilings

 

[chandler48]

How far up into the joists is the tie in point? From the toilet, the pipe would have to be below the joists since you are running at a 90 degree angle. THEN you make your turn and start your 1/4 per foot drop, which at 80 inches would be about 1 1/4". Is that tie in point at or below that point. It must be in order to catch the fall. AND it must be the size of your toilet drain, either 3" or 4".

 

[mjhaston]

Right now there is no tie in point. There is a cemented cap on the main drain (I believe). It's in a closet on the first floor. We have slab. That would extend into the ceiling rafters for the 2nd floor. It's a blank canvas up there now. No interior framing or anything.

I could always run my bathroom WITH the joist upstairs, if that would help, but then I'd lose a huge window area on the side of the house.

 

[Colbyt]

From the spot where I would tie in with the drain, I would run with the joist for about an 80" span. Then I would like to make a 90 degree turn and have a toilet and sink. I'm hoping something like this picture in the url. Maybe I need to put the toilet next to the shower to lessen the span?

So the tie in would be 80" left of the shower in this picture. The joist run perpendicular to the hard wood in the picture.

https://www.finehomebuilding.com/2017/05/10/bathrooms-sloped-ceilings

Even with using a cut down street el directly in to flange you are never going to make it in 7.5".

 

[mjhaston]

So I should probably run my bathroom WITH the joists and then everything would be within 80" of that tie in and within the same joist bay.

 

[Nealtw]

What is below the closet and what is below the rest of the run?

The shower drain can go thru the center of a joist.

 

[mjhaston]

What is below the closet and what is below the rest of the run?

The shower drain can go thru the center of a joist.

The closet is downstairs. I wasn't clear about that. That's where the drain connection would be.

 

[Nealtw]

The closet is downstairs. I wasn't clear about that. That's where the drain connection would be.

So how much of this area has closet below, a drop in a closet is standard stuff.



Where will the vent go up?

 

[mjhaston]

Upon further measurement, the drain would come straight up the back right corner of a closet downstairs. So dropping that closet ceiling may not buy much. That lands in the same joist as where I was hoping to put a toilet. I just pulled up the floor and it would need to run 60" in that same bay. Where I'm hoping the center of a shower would be, is 2 bays away and 40". Here's the best I could do with a diagram.

 

[Nealtw]

??????????

 

[mjhaston]

So that looks like it's doable?

 

[mjhaston]

Would it matter if the toilet and sink were switched?

 

[Nealtw]

Would it matter if the toilet and sink were switched?

Yes if you want to keep the 3" drain in one joist bay?


Take it for what's worth. I am not a plumber

 

[mjhaston]

I'm assuming that would be wise of me to do?

 

[Old Thomas]

3 inch and larger can be run at 1/8” per foot drop, smaller than 3 inch is 1/4 inch per foot. Newltw has a good layout including wye connections. Don’t use a tee or sanitary tee to tap the side of a horizontal pipe. A sanitary tee is ok to tap a vertical pipe.