vertical drain or sloped?

[mccm]

As part of my basement remodel I'm moving the kitchen drain to use a new roughin in the basement. It currently runs 20 feet across the ceiling turns and then 15 more feet to a 3inch stack. Removing this to clean up the ceiling.

I'm going to turn it immediately when it enters the basement to run along the foundation wall for 10 feet and then down into a new roughin drain. All this is 2 inch.

Question is, is it preferable to follow the ceiling for the first 10 feet and then straight down to the drain or slope it down to the drain at an angle? The drain at the floor will be about a foot from the wall due to the foundation so there will be a couple of 45 turns where it enters the slab.

If I follow the ceiling, I can hang the pipe from joists but will involve an additional 90 turn. Sloping along the wall I have to attach to the wall but would only use 45 turns.

Thanks

 

[Frenchie]

Flat (which for plumbing, means 1/4" slope per foot), then down.

I'm not sure on the explanation for why - one of the plumbers might chime in with it - but generally, you want to avoid slopes more than about an inch per foot, unless they're steeper one foot per foot. Anything between those two, tends to clog.

 

[Sponsor]

 

[Jay Mpls]

A good drainage system is engineered to drain at 2 ft per sec.
What you need to know is 1/4 per ft. and al will be good.
More pitch and you will have stoppage problems.
Good luck!

 

[Doherty Plumbing]

Flat (which for plumbing, means 1/4" slope per foot), then down.

I'm not sure on the explanation for why - one of the plumbers might chime in with it - but generally, you want to avoid slopes more than about an inch per foot, unless they're steeper one foot per foot. Anything between those two, tends to clog.

If you run your grade too steep you'll find that any solids that are in the water will get left behind and eventually clog up the drain line.

 

[Jimbo]

Well, we have 3 professionals here talking about the liquid outrunning the solids, and I never question the knowledge gained from experience.

On the other hand, that idea has been widely discredited by engineering studies. What do others think? Does any code prohibit any range of slope as long as it is minimum 1/4" per??

 

[hj]

slope

Make that three "experts" who say too much slope is bad, and ONE, me, who says there is no such thing as too much slope. Install it whichever way is easier and better looking. There is nothing wrong with horizontal into a vertical drop. EXCEPT, if excessive pitch leads to stoppages, EVERYONE has a problem because a vertical pipe has INFINITE slope.

 

[Frenchie]

Make that three "experts" who say too much slope is bad, and ONE, me, who says there is no such thing as too much slope. Install it whichever way is easier and better looking. There is nothing wrong with horizontal into a vertical drop. EXCEPT, if excessive pitch leads to stoppages, EVERYONE has a problem because a vertical pipe has INFINITE slope.

Hey, now - I said over 45 was okay...

But I just looked, and was surprised to see that there's nothing in the code about this; it only sets the minimum slope for drains.

(Combination waste-vent, they do set a max, 1" per foot. Which just underlines, I guess, how significant it is that they didn't set a max for drains)

Learn something new everyday...

 

[Doherty Plumbing]

Make that three "experts" who say too much slope is bad, and ONE, me, who says there is no such thing as too much slope. Install it whichever way is easier and better looking. There is nothing wrong with horizontal into a vertical drop. EXCEPT, if excessive pitch leads to stoppages, EVERYONE has a problem because a vertical pipe has INFINITE slope.

Well that's because in the vertical drop everything will fall around the same speed and there should be water AFTER any solids to help wash those solids further out downstream once the piping goes horizontal at the bottom. However vertical drops aren't good either. Go into any apartment building and open up a horizontal run at the bottom of a vertical soil-or-waste stack. I think you'll find a good portion of it plugged up with gunk. I have seen 6' sections 98% closed off with build up at the bottom of a S-O-W in apartments. But after that initial 10' or so the piping is pretty clean and clear... odd hey.

However if the drain is run horizontal you just might find that a solid in the water isn't all that buoyant and sinks in the water till it's touching the invert of the piping. It just may have more friction then the water and in a long run you'll find that the solid eventually can't keep up to the liquid so it gets left behind.

You want the water moving along at a nice even pace so everything in the water can keep up and be carried out to the main sewer.

Anytime you give water a chance to outrun what it's supposed to carry away you're going to have long term problems that will require regular maintenance. In a single family home you may not notice as quickly that you have problem for the simple fact that you're not running a lot of water in the grand scheme of things.

But this is just my opinion based on my experiences out in the real world.

 

[Jetlag]

Hey, now - I said over 45 was okay...

But I just looked, and was surprised to see that there's nothing in the code about this; it only sets the minimum slope for drains.

(Combination waste-vent, they do set a max, 1" per foot. Which just underlines, I guess, how significant it is that they didn't set a max for drains)

Learn something new everyday...

Isnt that 1/2 " max ? I believe the 1/2" max or 45 down still applies for drains, it allways has applied. Not sure why the IRC didnt include it. I bet it is still in the IPC

 

[Frenchie]

My IPC book's out on Fire Island; so I haven't a clue.

 

[mccm]

Back after the weekend, thanks for the replies.

Not sure which I'll go with but it seems putting a cleanout at the bottom where it enters the floor would be a good idea since it will be conveniently in a closet.

 

[hj]

slope

quote; Anytime you give water a chance to outrun what it's supposed to carry away you're going to have long term problems that will require regular maintenance.

It isn't going to happen, and MANY universities and test labs have proven it. As far as "excessive pitch" is concerned, I have ALWAYS installed the pipe as necessary to USE UP the available pitch, and have NEVER had to go back to maintain it for any reason, much less because of excessive pitch. I will see your "real world experience" and raise it with my "60 years of real world experience" in ALL phases of residential and commercial plumbing.