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How many 90 degree turns are OK in a drain pipe?

Posted by melissastar (My Page) on
Sun, Jul 4, 10 at 21:57

I'm in the early stages of a major remodel of an old row house and just noticed that the drain pipe the plumber installed for a new washer on the second floor is way too close to the trim of an old window, which I wanted to keep as is, on the 1st floor. I'm pretty sure the pipe is so close to the window trim because there's a support beam for the second floor he was avoiding just to the left. But leaving it as is means cutting off the trim or losing the window, when the chase is built around he pipes.

So, I'm wondering....is there some limit to the number of 90 degree turns , a drain pipe should have? There are three in short order as the pipe comes up from the basement to the first floor. Could we have it make another 90 degree turn a few feet up to avoid the window and then back again above the window where there will be a bulkhead anyway to accommodate some other design/plumbing issues?

Or is this asking for clogs and trouble down the road?


Follow-Up Postings:

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RE: How many 90 degree turns are OK in a drain pipe?

Why are you using 90 degree turns?

45s are easier on flow and snaking.


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RE: How many 90 degree turns are OK in a drain pipe?

melissastar,
you need to distinguish where the bends are.
1. in the vertical part of your whole drain system.
2. in the horizontal part.
3. in the horizontal part that is defined as "trap arm" which is between the washer standpipe's P-trap and the place where venting is first connected. This might only be a couple inches long, but it is a different segment with its own rules. Sometimes people try to route this pipe around obstacles. Is this your case?

Three different kinds of constraints.
I'm assuming you have a standpipe.

I read this about 90 degree bends: "There are three in short order as the pipe comes up from the basement to the first floor" so I'll guess you were referring to the vertical part. Is this the correct reading?

I'm not a plumber, not a plumbing inspector, and not a plumbing instructor. Nor do I act as one on the internet or on TV shows.

Hope this helps.


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RE: How many 90 degree turns are OK in a drain pipe?

Davidrol: You guessed right...they are in the vertical part. And They are in the vertical part. And as brickeyee noted....45 degree turns could substitute...I just hadn't thought of that. (Are they really called 45-degree angles...aren't they really 135 degrees?)

I'm trying to route the pipe which will run up an outside wall around an old,rather charming window that I'd like to protect. At the point where the drain comes up from the basement and where it goes from the ceiling of the first floor to the floor, there are no options...it has to be where it is to get around double joists. A straight line between those two points cuts too close to the window frame to allow for framing and dry wall. BUT....if I can create a "bend" (like a river bend that swings out and then back) in the vertical drain, I can save the window.


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RE: How many 90 degree turns are OK in a drain pipe?

"like a river bend that swings out and then back) in the vertical drain" sounds like an offset. Three keywords for web searching, just to get an image: double offset tubular. But you cannot use these tubular pipes; I just gave you these words so you can see products with shapes you probably want to see, to re-assure you that this shape is A-OK. You cannot use tubular in this application.

To find 135 degree bends, search using these key words: "1/8 Bend".
Try "1/8 Bend Street Ell" as well, to see a more compact fitting. Every little bit helps.
Also, "Copper or PVC" can help narrow down choices.
Copper is more compact than PVC, by the way.

The above is information, not "final answer". Don't do anything irrevocable based on this.

hth, melissastar


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RE: How many 90 degree turns are OK in a drain pipe?

YES, YES, YES! That's exactly what I'm talking about davidrol! So it should be fine to put one of those below the window and one above, routing the pipe away from the window....terrific!


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RE: How many 90 degree turns are OK in a drain pipe?

you have to build the shape you want with parts. Search on "DWV fittings".


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