Clean Kitchen Bath Drain Install

[CCCBuilder]

Heya. I am getting ready to set my sink and will be installing the drain lines. My plumber who did the rough in appears to have placed the drain line a bit low. Perhaps he forgot about the cabinet having a raised false bottom or just likes to keep it down low.

Anyrate, I have only done a few sink drain installs and on those I always attached a tail pipe into the main drain line, which connected to the exit of the trap. This made the trap set lower than the drain line installed in the wall. In my case, that may require notching the cabinet bottom out and I'd like to refrain from doing so. I have seen some photos on the internet where it appears there is a 45 off the main drain and another 45 after the trap exit...allowing you to have the trap above the roughed in drain line. I'm concerned that may not be code compliant? My sink won't have solids going down it...so I think that would drain fine. Any suggestions here? I'd like to refrain from cutting the cabinet floor, but also have a proper system.

Thanks!

 

[Cacher_Chick]

The trap arm must be straight (not to exceed 1/4" per foot slope) between the trap outlet and the vent riser. Any horizontal jog can cause the trap to siphon thus is not allowed.

 

[Sponsor]

 

[Widgit Maker]

Are you saying that when you assemble the trap, the trap arm is above the drain line coming out of the wall?

 

[CCCBuilder]

So, no vertical drop makes sense because the drop would siphon water from the trap because it has not yet met the vent. Yes, if I were to install a trap the trap arm - or the exit end of the trap - would be above the roughed in drain unless I were to cut out a hole in the cabinet floor for the trap to set lower than the roughed in drain. Damn....

 

[Smooky]

A picture might help because I'm not familiar with a "Clean Kitchen Bath Drain"
You may be able to save space if you install a different type of drain. The old pop-up tailpieces take up a lot of space. There are some newer type drains that take up less space. There may be several ways to make your clean kitchen bath drain work.

 

[Widgit Maker]

Yes, if I were to install a trap the trap arm - or the exit end of the trap - would be above the roughed in drain

Then you do not have a problem. You simply install a longer tail pipe out of the sink and lower the trap. When the rough in is higher than the trap arm, then you have a problem.

Now if the problem is that you don't have enough between the trap and the floor of the cabinet without cutting the floor as indicated in your last post. Cut out the drywall and rework the drain pipe in the wall. Assuming PVC pipe, that should be a 30 to 45 minute task.
Cut a hole large enough to work in. It is just as easy to patch a large hole as it is to patch a small hole. Cut the pipe at least 2" below the tee. Cut the pipe above the tee at least 3" higher than you want the tee to be. Cut enough pipe off the top of the tee to raise the tee up to the desired level. Use a coupling to put the short piece you cut off on the drain pipe below the tee. Use another coupling to put the tee on to raised drain. Use a shielded rubber coupling to reconnect the tee to the vent pipe above.

Put a couple strips of 1/4 or 1/2" plywood across the hole, then screw the piece of drywall you cut out to the plywood strips. You can seal the drywall with drywall mud and tape or you can just caulk it . Doesn't have to be pretty. The cabinet will hide the patch.

 

[CCCBuilder]

The cabinet and countertop are now set so no drywall work to be done. Looks like my only option is to cut the floor out of the cabinet. What a crappy situation due to poor planning. I'll maybe get a picture but from discussion it sounds like there is no option of having the trap above the horizontal drain pipe sticking out from the wall. My title is explaining I wanted to do this as clean as possible...without tons of fittings or tearing up the false bottom of the cabinet, which is quite nice right now.

 

[Reach4]

there is no option of having the trap above the horizontal drain pipe sticking out from the wall.

True for practical purposes. There is probably a situation where you could add an AAV before dropping the exit pipe down. You will have doors covering under the cabinet, I presume, and you will cut the slot nicely.

 

[Widgit Maker]

Well there is another way if you are willing to do the work. That is cut out the back of the cabinet and the drywall. Do our plumbing and patch drywall. Then make a false back for the cabinet.
Now that can be a little tedious. You will have to cut openings for the drain and the supply pipes. It is almost a certainty that the false back would have to go in as two pieces. The joint between the two pieces can be neat enough as to not be distracting.
The backs of cabinets are seldom the same wood as the cabinet itself. A nice piece of 1/4 luan with a lacquer finish can look quite nice.
A tedious task. I guess it all depends on how much you want it.

What you propose to do with the trap higher than the drain stub out amounts to an "S" trap, which is not allowed by code. The addition of the AAV makes it meet code. Put a 90 on the stub out, go up and put in a sanitary tee, put your AAV in the top of the tee. Put your trap arm in the side port of the tee. I wouldn't worry about the possibility of the AAV failing. An "S" trap that close to the vent would never give you a problem even with out the AAV.

 

[hj]

A picture would be an immense benefit, because from your description the drain out of the wall is almost down to the floor, and NO "competent" plumber would ever install it like that.

 

[Cacher_Chick]

It's gotten pretty common when installing a disposer on some of the new deeper sinks, the rough in needs to be 14-15" off the floor.