Height of horizontal rough-in for drain?

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Old 04-29-13, 09:13 PM
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Height of horizontal rough-in for drain?

Hi everyone,

I have (quite) a bit of a headache with my rough-in plumbing inspection. My contractor is doing the work, but I'm not sure he really understands the inspector's complaint. I really need to have the inspection passed during the next visit, so here I am, trying to understand what exactly is the problem to make sure that the contractor fixes it correctly.

What we're doing: we're adding a new sink in a (new) laundry room. The picture shows the rough-in plumbing as it exists. In the left circle is the drain to which the sink will eventually connect. The inspector says that it must be 21 inches high.

As it exists, it is about 20.5 inches from the ground. The contractor thought that the inspector was being nitpicky about half an inch. But the inspector didn't seem unreasonable, so I'm not sure that was really his point. My contractor explained to the inspector that he couldn't make it 21 inches because there's no room to connect the drain to the main drain (circled to the right). The inspector then responded that he might then have to dig a bit into the ground to get access.

What exactly is the inspector complaining about? Insisting that it be 21 inches from the ground didn't make much sense to me. Was he saying that it must be some distance from the connection to the main drain? If that's the case, the contractor's fix still wouldn't work.

Thanks for any input!

P.S. Oh and in case this matters, this is in the basement on a concrete slab.
 
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Old 04-29-13, 09:39 PM
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Hmmm... I have to check to code on that as I dont know off the top of my head. What is to the left of the sink? Just wondering where that pipe goes.

Look at the sticky's at the top of this forum. All the codes are there.

It seems simple enough to make it higher. Probably can put it on the horizontal and tie into the next bay. Or with cast he can just get a longer sweep for that Y below the H/C water pipes.
 
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Old 04-29-13, 09:58 PM
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Thanks lawrosa. To the left of the sink is the drain for the washing machine.

A somewhat unrelated question: what's the difference between a Y and a combo? The inspector also complained about the Y. He said we must use a combo. So the contractor went out and bought a combo, showed me both (the Y and the combo), and I swear I couldn't tell the difference to save my life. Then he said the combo has a slight curve to the angle, and then I could see that yes, they are ever so slightly different. So what's the difference? Is the inspector really that nitpicky, or did the contractor get the wrong thing?

I thought moving the drain higher would be ok, but if it's too high, would that make the laundry sink inconveniently high? It's already at 24" now. Would that pose other problems?

Thanks again!
 
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Old 04-30-13, 12:14 AM
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The Y needs to have a sweep when going from vertical to horizontal. The inspector is right.

You need to explain more to my on what he said about the height exactly?
 
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Old 04-30-13, 01:20 AM
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He basically said that the height of the horizontal rough-in is wrong. He mentioned something about 20 or 21 inches.

The contractor then said, "well, I can't really lower the [horizontal section that connects the sink drain to the main drain] any further, because I'm already connecting it at the lowest point [of the main drain] that I can access."

The contractor then asked, "can I connect it to the clean-out [of the main drain, which you can see in the picture, circled, just above the slab]?"

The inspector then said, "no. The clean-out is the clean-out, and you'll need to keep it. You might have to dig a little into the ground if you have to."

Pardon me--I know this is really vague--but I was trying not to interrupt his conversation with the contractor. At the time, I also thought that the contractor understood the inspector, but now I'm thinking that maybe he doesn't.

The contractor seems to think that the height is not high enough--so, he raised it from 20.5 inches (from the ground) to 24 inches now. But I don't see how that makes any sense. I can't find any part of the code that stipulates how far the horizontal rough-in should be above ground. Or is there?

So my only guess is that there's some stipulation of how far the horizontal rough-in must be to where it connects to the main drain. But if that has to be 20", then I think I'm screwed--there's no way to get that without having a sink that's 4ft tall.

Is there anything you can see in the picture of something that he might have done wrong?

Thanks again.
 
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Old 04-30-13, 03:02 AM
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Mike's the plumber. I am trying to learn with you. I only have one question. If this is a plumber, why is he using so many no-hub fittings? Isn't that sort of expensive when normal glue up fittings would work? Just curious. Oh, one other thing. The inspector rules, so try to be nice when making your points.
 
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Old 04-30-13, 07:04 AM
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I can't find any part of the code that stipulates how far the horizontal rough-in should be above ground. Or is there?
I dont think there is a height stipulation. It depends of the fixture. I think the issue is the distance from the sink sanitary tee to the Y that may be the issue. But thinking about it I believe that is not the issue either.

Why you are using cast iron is beyond me. I would have used PVC. My pic shows how I would have done it. Note that the two vents that tie in together will be higher in the ceiling. I am just showing it like this for illustration.

I think its a whole venting issue that is the concern....
 
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Old 04-30-13, 09:53 AM
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Thanks lawrosa.

Just talked to the contractor again, and this is his understanding: since the combo is taller than the Y (which he used to use), using the combo pushes the drain higher (from 20-21" to 24"). Therefore, the inspector might complain that this is too high. In a perfect world, we would move the horizontal drain lower so that the drain can be lowered, but he (claims that he) can't connect it to the main drain any lower, without having to dig around the slab and replace part of the main drain.

This makes a bit more sense to me. (Does it?) However, this really sucks since I don't see an easy solution. Is the drain at 24" too high? If I use a shallow sink in the laundry room, would that be ok?

Oh--we had to use cast iron because we're in San Francisco. Contractor says that it's code here.

Thanks again for all the input.
 
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Old 04-30-13, 10:07 AM
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So your saying its too high? Well the plumber should have put the sink sanitary t on the horizontal and vent as I show.

I would assume its too much work for him to redo since its all cast. And he probably does not want to fix it right because its out of his pocket, so therefore nit pick to try to get the inspector to pass it.

The inspector will make him do it right if its still not acceptable.

What sink are you getting? I can look at the specs.

If he puts the t on the horizontal from that line coming around from the stack then the height will be good I assume.

What is the height of that arm coming from the stack from center?
 
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Old 04-30-13, 10:50 AM
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I'm thinking that the inspector is more concerned with the "fall" on the horizontal piping from the sanitary tee to the connection at the stack.
 
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Old 04-30-13, 03:34 PM
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Wow, didn't notice it was cast iron. Just figured he was using it on ABS. Thanks for the info.
 
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Old 04-30-13, 04:13 PM
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I got this. Dont think the trap is high enough above the tie in to the stack as I believe furd stated.....

905.4 Vertical rise of vent.

Every dry vent shall rise vertically to a minimum of 6 inches (152 mm) above the flood level rim of the highest trap or trapped fixture being vented.







905.5 Height above fixtures.

A connection between a vent pipe and a vent stack or stack vent shall be made at least 6 inches (152 mm) above the flood level rim of the highest fixture served by the vent. Horizontal vent pipes forming branch vents, relief vents or loop vents shall be at least 6 inches (152 mm) above the flood level rim of the highest fixture served.
 
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Old 05-01-13, 05:55 PM
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Thank you lawrosa. I will check with the building department, and report on my findings after my next inspection. Thanks everyone.
 
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Old 08-08-13, 11:35 PM
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Hi. This post is a few months old so likely your problem has been solved already, but just wanted to offer a suggestion. If it has been resolved, let us know so others can perhaps benefit.

Anyway, the last post about the dry vent doesn't apply, or I should say is already acceptable if it rises up through the roof. Essentially, a vertical dry vent stack would be a pipe that goes to outside your house to let sewer gas vent to the outside when no water is in the pipe and also to allow air to be drawn in behind draining water to drain (think of how water stays in a straw when you put your finger over the top, but drains out when you open the top). Anyway, that "dry" vent is going to carry up and is not allowed (by most code) to turn horizontal until it is 6 inches higher (as defined by the example code) above the highest trap. (Think drain when they say trap). In most bathrooms, your shower drain is low on the floor, the toilet too, but its usually the sink that is the highest, at waist level. If (a big if) water clogged and backed up through all drains the vent stack would be dry higher than the highest fixture, in most cases your sink. That's almost always a very easy concept once you think about it some, but a more complex situation would be a 2 story house (or multi story building with many floors) where if you imagined fixtures on a higher level pouring down that stack and past your lower level fixtures, while it would be "dry" as long as nonebof the upper level fixtures were draining, essentially, everything down would be a "wet" vent because water *can* come down if an upper level fixtures is ran. In that case, the vertical stack cant turn horizontally, it must go up and then, if abiding by the sample code(check your state/local for variances) it would need to go up at least 6 inches higher than the 2nd floor highest trap, ie likely a sink. So, while the contributed code is still important and good to know, it may not be what the inspector is talking about.

So that only leaves me a few ideas in regards to the height question.

First, there is some sort of code I believe with height in regards to a washing machine drain. If it has a P trap at the bottom of the washer drain, which it should to "trap" sewer gas from entering your home via the washer drain, you may want to look in the code about that height.

My BEST guess, without knowing more, is that in the codes there is a chart that tells you that for every foot of horizontal distance, there is a corresponding number of inches per foot required, depending on the diameter of the pipe. It would appear you have a 2" diameter pipe and it is running roughly 5' (just an eyeball guess based on the photo) so, if your state/local code says you need (as an example) 1/4" drop per foot with a 2" pipe, then the pipe over on the left on your photo would need to be 1 1/4" higher than where it meets the main drain stack on the right. So, perhaps, just a guess, the inspector thinks there is not enough drop per foot heading towards the main stack. If the pipes on the left cannot be raised easily (as I can see they are running through holes in the stud wall) perhaps he is suggesting to lower the stack on the right which would allow a slope in the connection. When it comes to the slope of the horizontal pipe, think about how water rolls down a hill or driveway. Same principal, the "horizontal" pipes must have slope and your state/local codes will have a chart that defines how much you need per foot of horizontal distance to comply. Likely it would still work but the codes are usually written to ensure best practices and slopes provide a better chance that water will not stand in the pipes or any solids and then clog.

Hope that information is helpful to someone if not you and I'd be interested to hear what the inspector said to clarify.
 
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Old 08-09-13, 06:33 AM
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t would need to go up at least 6 inches higher than the 2nd floor highest trap, ie likely a sink. So, while the contributed code is still important and good to know, it may not be what the inspector is talking about.

Actually its 36" above the highest flood plane as I know it.... That would be the top of the bath sink most liklely..


First, there is some sort of code I believe with height in regards to a washing machine drain. If it has a P trap at the bottom of the washer drain, which it should to "trap" sewer gas from entering your home via the washer drain, you may want to look in the code about that heigh
t.

18" afaik....


Im curious to what the result was.....
 
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