Is sink plumbing vented correctly?

Old 06-30-10, 12:18 AM
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Is sink plumbing vented correctly?

Hi. I am a do it yourself person and we are redoing our first floor bathroom. We totally gutted it to the studs. Starting to redo plumbing now. Took out all of the old metal pipes and replaced with PVC.

One question. The way the old sink drain was installed it clogged alot because the drain was actually running up hill inside the wall just enough to make me snake it about every 2 months or so.

To stop this problem I am wanting to reroute the drain some but want to make sure I am doing this by code.

The way I want to do it is have the drain under the sink go into the wall and then drop vertically about 6 inches and then begin to go horizontally (with a slight decending slant of course- trying to adhere to the 1/4 drop for every foot rule) for about 2 1/2 feet at which time a vent pipe will go horizontal and the rest of the drain pipe will go about another foot to the main drain.

I want to make sure that the vent is correct.

As I mentioned it will go about 3 feet total after it enters the wall before it vents. The first 9 inches will be a vertical drop behind the wall to the basement and then and then it will run horizontal for about 2 /12 feet. before it reaches a vent pipe.

The tub on the other side of the bathroom had this exact same design but it only dropped about 6 inches instead of the 18 inches.

Thanks for any advice.

I will try to get pictures the next time I have the time and post with this.

Old 06-30-10, 02:26 PM
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You can't do what you want, a vent must go UP 42in. above the fixture it's connected to and then tie into another vent line; what you are creating is an s-trap which is a no-no.

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