Hi,

I'm putting in a new bathroom on the third floor. I don't have good access to the existing stack, so I'm going to run a new, additional, 3" stack. The drain will service a toilet, bath tub and sink. I want the drain pipe to "hug the walls" to keep the pipe out of the way and box it in later.

Is there any limitation on how convoluted this 3" drain can be? Assuming I maintain the proper pitch along the way and use long radius elbows, I'm going to go down through the floor, horizontal for 2 feet, down 8 feet, horizontal for 16 feet, down 2 feet, horizontal for 25 feet, down 8 feet then 15 feet to the septic tank.

Any thoughts?

Thanks,

Glenn

Hi,

There is no limitation on how convoluted your vertical pipes are vertically, but try and eliminate as much 90's. Also remember with all that 90 bends that there is a likely chance that liquid waste would leave solids behind because it is heavier and would be left behind. But don't forget a cleanout on the main floor as its required. The 2nd and 3rd floor does not require a cleanout. Goodluck

I myself would access the existing stack on the third floor no matter what. I'd hate to have to deal with a clog in about 60 feet of new drain, most horizontal, now matter how good the pitch and turns.

Do you have enough room for a 14 1/2" slope? If you can't access a closer stack how many cleanouts do you plan on installing? Regards, Tom

I tend to agree with one of the previous posts. If you can , tap into existing stack. It will be more economical - because what you describing seems to be way too much pipe / turns + too much work to run it all the way to the septic.

Tom,

I plan on achieving the 14-1/2" drop along the way. Each horizontal run will include the 1/8" drop per inch.

I was only going to put in a clean out at ground level, but it sounds like I will include one on the second floor as well.

1/8" per inch? Is this a typo?

Hi all...

Good point, Bob (ballengerb1)...

1/8" slope per foot of pipe is usually only for 4" or larger pipes, however, Afaroo (another team member ;)) posted a code that actually allows an 1/8" per foot for 3" pipe, too... go figure.. huh?

I'd increase the slope to 1/4" per foot if possible... shorten the run if possible and install another cleanout where the pipe is accessible upstairs... for sure!

Supposed to install a cleanout for every 135 degree change in direction... if memory serves me.

Glad to help with work on cutting into the stack.

Mark

By the Code I work under, we are required to put clean out on total of every 135 degrees of turns.

In addition, Inspectors often asks us to put clean out on every 90 degree of horizontal turns.

You cannot go wrong with clean outs. They cost few dollars and will save you lots of headaches later.

Funny... I was revising my post as you posted Milo. Our codes agree on this fact!

:)

I could go with 1/8" per foot but not if a toilet is part of the picture. Codes vary but in thuis case I'd lean toward a stricter code and I'd put the toilet at the end of the branch drain.

Yes, 1/8" drop per inch was a typo. Should be 1/8" per foot which is correct for a 3" pipe.

Make it 1/4" per foot / per 3" pipe...

Hi again,

My answer is 1/4" per foot on 4" pipe. If installing 4" pipe, 1/8 per ft is permitted but because of reduce flow you must total fixture units and multiply by a factor of .80.
But it sounds like it is a toilet, lav, tub/shr only so it would be a 3" stack and horizontal. Code says 1/4" per foot with 3" pipe and not 1/8" . Horizontal drain pipes are allowed a max of 135 degree change in direction before a cleanout regardless of pipe size. If 3" horizontal pipe is installed at 1/8 per ft then definitely you would have liquid waste ahead of solids. So remember with proper slope of 1/4" per ft there would be better flow as it would be with 1/8" per ft which is reduced flow. THANKS