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Has anyone plumbed a pedestal sink thru floor (not wall)?

Posted by dawnr (My Page) on
Sat, Nov 24, 07 at 14:19

With a 200 yr old, there are always surprises. I don't want to cut into wall, and want a pedestal sink. Has anyone just run the drain pipe into floor. I know you will see it, but you see everything half way down and into the wall when you plumb that way anyway. (guess I am wondering how bad it would look).

Follow-Up Postings:

RE: Has anyone plumbed a pedestal sink thru floor (not wall)?

Never mind how it would look, it is code prohibited.

The maximum allowable length of the sink tailpiece is 24" vertical measured from the sink drain opening to the input of the trap.

RE: Has anyone plumbed a pedestal sink thru floor (not wall)?

I'm not sure why its any different than plumbing under a cabinet? The pipe comes down from the sink drain, say a foot or so, then there's the trap,then the pipe going into floor. Am i missing something?

RE: Has anyone plumbed a pedestal sink thru floor (not wall)?

Yes. If the drain water has to fall too far prior to the P-trap it could have sufficient force to push all the water from the P-trap, allowing sewer gases into your home, a potentially LETHAL situation. Run the drain correctly.

RE: Has anyone plumbed a pedestal sink thru floor (not wall)?


A "foot or so" might probably be less than 24" sooo> Getting the tailpiece from the drain to the trap and then into a position to go straight down is the hard part in my opinion.

But Dawnr; how much less scary do you expect under the sink to be, than behind it? If the potential sink location is on a 2nd floor, I can't imgine not having to bust into the ceiling under it too, even to run the drain straight down. I just went through the same exercise myself including the installation of a pedestal sink. An old timer warned me they are a PIA. It was tight back there. When you are done with the plumbing, pad the inside of the studs where you bust out the plaster and patch it up with sheetrock. As lazypup points out though, there are lots of things in "the book" to tell you what you can and can not do. Get the book, or get in touch with someone who can get the water from your sink to the sewer. You didn't even mention getting the nice clean water to the sink. It's half the battle.

Good luck, and more importantly, think it out, and make it work.


RE: Has anyone plumbed a pedestal sink thru floor (not wall)?

First of all, you have to consider how the line is vented. Typically a lavatory drain is connected to a tee on a riser. The top of the tee continues vertically up to the roof to vent the bathroom group.

Next, the code expressly prohibits using S-traps. To connect a pedastal sink, the sink would first be connected to a P-trap and there needs to be a horizontal run equal to 2 times the trap diameter from the trap weir to the riser.

RE: Has anyone plumbed a pedestal sink thru floor (not wall)?

I guess I have an illegal setup now then. Its a first floor bathroom, btw, and I currently have a wall hung sink plumbed thru floor. The pipe coming out of sink is 6 inches, then a trap , then a pipe thats curved (shaped like a candy cane! haha! I am a plumbing dunce)comes out of trap and straight into floor (18 inches). I guess the trap with the curved pipe creates an S trap? Illegal? but always worked fine for 18 yrs. Guess I won't be able to get a plumber to do this. Thanks. (so even with a vanity type sink I need to plumb thru the wall?)

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