Haven't done a lot of household plumbing...we're getting new counter tops installed next week, we're installing a new sink and the drain is back a little further in the sink than this one so I have to redo the drain.

The new sink will also have the disposal on the main drain so no tee-ing of the drain will be needed.

Since I have to redo it I would like to fix the janky mess shown below.

First off do I have enough room to fit a P trap? You're supposed to have 12" of straight pipe after the trap right?

Second, this stuff is all some kind of slip, compression joint crap, I don't know what but it's fallen apart while the dishwasher was running before which is not pleasant. What's the best way to do this, glued PVC with a couple unions?

 

Welcome to the wonderful world of plumbing. Yes a standard P trap will fit and slip joints are the way they are put together. Real plumbers will be in soon but I always try to dry fit everything before I start cutting the plastic parts. Try to keep as much pipe as you can slip into the coupling.

 

We can't see the end of the last pipe in your photo. It looks like the vertical is also a piece of slip fit plastic. Do you have the houses piping visible in the cabinet?

 

First off you have for all practical purposes a "S" trap even though they used a P-trap. "S" traps are no longer code compliant.

Best will be to remove every thing except the short section of pipe coming up from the floor and do something like this:

 

I think Ray hit the nail on the head. Cut it all out and replace the vertical portion in 'hard' cemented PVC with a sanitary tee and AAV (per the photo). Then get a slip-joint PVC kit for your sink (or double sink) and connect it. You may need an extension here or there, but it should be a much simpler setup than what you have now.

 

That is quite the Rube Goldberg you have there. Obviously took a lot of trial and error to make that snake eventually hit the floor outlet. Replacing it will have a much cleaner look and it will be a better functioning sink as well. The AAV will make all the difference.

 

I've never seen a sink with a vent under it. Where do I find one of those?

So, all the drain pipe fittings they have at lowes have threaded "compression" ends on them...is that OK to use if I glue a threaded adapter to the stub coming out of the floor?

I picked up a P trap, but I think I'm going to have to wait until I'm ready to put the sink in to see what fittings and such I really need.

BTW, whoever did the plumbing in this house loved S traps...they're under every sink in the place. Our basin sink in the basement has a DOUBLE S trap under it for some reason.

 

My sister's house, built in 2006, has the vent under the sink just as the picture Ray posted. The vent fitting itself is called a Studor for its manufacturer or an Air Admittance Valve (AAV) generically. Other companies beside Studor make them and they are readily available at most big box mega-mart homecenters. Note, a few areas still have not approved their usage.

There is a difference between DWV (Drainage, Waste and Vent) fittings and trap parts. The DWV is heavier walled and is glued in place whereas the trap parts are connected with "slip" (not compression) nuts and coned washers. The slip connections are far more forgiving as far as length and allow you to take the entire trap apart for cleaning.

That is the wisest way as it is almost impossible to figure out what you need until you actually do the job. I find it is often easier to buy every conceivable fitting and then take back the ones I don't use. You will need a glued coupler at the base, a section of DWV pipe to a "sanitary tee" and then another section of pipe with a female threaded adapter to receive the AAV. The AAV needs to be as high as possible yet still accessible for replacement if it fails years down the road. The side branch of the sanitary tee will need a "trap adapter" glued into it and from there to the sink drain will all be done with the trap piping using the slip nuts.

I'd like to see a picture of that. Many decades ago S traps were common but it was found that they were prone to siphoning out the water seal under certain circumstances.

 

If you will step back and give us a full view of under the sink we may be able to give you a better description of exactly what you need.No. You will glue a PVC coupling to the stub. Then a glue a piece of PVC pipe. To the PVC pipe you glue a sanitary TEE so it is at the height for your trap.In the top of the sanitary tee another short length of PVC pipe and on to it is the AAV. A threaded trap adapter is glued into the arm of the PVC trap. That is where you start using slip fittings.

 

Hey guys, last night I pulled out the counter tops, sink etc. Got the drain all disconnected and got a better look at what was going on.

First problem- the stub coming up out of the bottom of the cabinet is not your standard schedule 40 PVC, it is yet another piece of that thin wall 1 1/2" drain tubing that is slip fit into what I assume is the actual stub under the cabinet (the stub piece is not fixed and I can slide it up and down). So, that is apparently what I have to work with, I don't want to take the cabinets apart to try to figure it out further.

I found out the drain was all put together with those flanged, gasketed drain pipe pieces, some actually had the flange on the pipe itself, some were just "slip fit" in.

Does this absolutely have to have a vent if the old one didn't? I picked up a 1 1/2" sanitary tee, vent and such but it's made for the schedule 40 PVC and won't fit this stuff. What are my options here? I have to go to Lowe's this afternoon and return a bunch of stuff and see what I can figure out will work.

FWIW, were are putting a garbage disposal on the main drain of the sink so everything will be draining through it, if that matters.

 

If you don't have schedule 40 PVC coming up through the cabinet then you are stuck using slip fit/compression fittings... which isn't proper. Yes, the correct way would be to remove the cabinet or the cabinet bottom so you can glue on some sch40 to get up into the sink area. If you think it's too much work consider what repairing a rotten floor will be. Those slip fittings are intended for exposed locations only. Concealed and out of sight they tend to get bumped and moved when installing the cabinet and drain piping and they frequently leak.

 

Well, they did OK in the existing installation, there are lots of questionably done things in this house. They're coming to install the counters today so I can't take the cabinets out and try to redo this whole drain, so I'm just trying to work with what I have.

I'm not sure who did the plumbing in this house but I'm not a fan.

 

So do you have access under the floor. If not I'd consider cutting a hole in the the floor of the cabinet.

 

It doesn't matter how much perfume you pour onto a pile of manure, it is STILL a pile of manure.

The ONLY way to do the job correctly is to take out all that thin-wall slip joint piping and redo it with the proper PVC or ABS piping, transitioning to the slip joint piping at the trap itself. Anything else is a cob job.

 

I have had to replace more then one cabinet floor under a kitchen sink (because of water damage to particle board usually) so it isn't impossible just challenging. However a one foot by one foot hole around the drain as I earlier suggested would be much easier to cut and repair. If you have no access from below the floor the 1'x1' hole would be the way to try first. Then you can decide what to do next. You do not want to leave it as is.

Short story: Went out to do renovation for a "house flipper". First thing I noticed going in the back door was the ground was wet. The customer blew it off as rain. That I didn't believe because it hadn't rained for weeks and was summer. Bottom line kitchen floor was plywood fastened to wood runners over concrete to make it level with the rest of the house floors. There was a leak from below the bottom of the kitchen sink cabinet.

Ended up having to tear out the whole floor to dry out standing water on the concrete under the wood floor. Stick built cabinets so no way to salvage the cabinets which had to be removed to remove the floor. End result one very unhappy "house flipper".

 

I would definitely second Ray's suggestion of cutting a hole in the bottom of the cabinet so you can run Sched 40 up. Especially since you can feel the pipe turning and moving - it means you already don't have a great seal underneath the cabinet and are just asking for a leak, if you don't have one already.

 

Soo...if I wanted to get at the pipe stub in the floor...what's the best way to do that? It looks like the cabinets were put in and then a hole saw was used to cut holes for the water pipes and drain. Not sure how I would cut a larger hole to get in there better.

Also- do these slip/compression fittings have to be perfectly straight to not leak? We needed our sink to work so I had to put it together as-is. I hooked everything up and it works, but the 90 degree elbow I have to connect the P trap to the pipe stub is leaking ever so slightly when water goes down the drain, from both sides. I'm not sure why, everything is snug and I tried to get it all straight (it's hooked directly to the garbage disposal which just had a slip fit end on it). Ugh

 

I forgot to add...apparently I can't access the drain from underneath. The PO partially finished out the basement, they put up drywall and a dropped ceiling, and I can kind of see where the drain is coming down but it's behind the wall and a floor joist, so inaccessible from the basement unless I tear part of the wall out which I don't really want to do if I don't have to.

 

Easiest is to cut out a section from the bottom of the cabinet as has been mentioned. The cutting doesn't have to be neat or pretty. Then after the work is done you can cover the opening or the entire bottom of the cabinet with a piece of plywood or other sheeting.

 

You can use a jig saw or reciprocating saw to cut a larger hole. As Dane mentioned, just cover the whole base when you're done.

They do need to be pretty straight. You also want to ensure you don't overtighten them. They are made of a soft plastic that deforms pretty easily if you wrench them down too tightly. Also, make sure you have the gasket/washer in the correct direction. The sloped side should be towards the fitting, with the flat side against the plastic nut.

 

Given the location I would cut out about a one foot by one foot section in the corner. If you use a Sawzall wit a one foot long blade it should be able to cut right up to the side. The trick is to hold the saw so it only goes about an inch and a half deep. You'll need drill a couple of one inch holes with a spade bit to start the saw. The remaining two cuts can mostly be made with a jig saw.

When you have finished putting in a stub you will install a new square with a hole for the stub. I'll detail how to fasten the new square if you need help. A scrap of sheet vinyl cut to fit the whole cabinet and glued down will hide your work.

 

OK, I'll have to see what I can do in there. I have a sawzall, but no jig saw. It's pretty tight in there. I'm thinking it might actually be easier to drill a few holes and cut between them with a keyhole saw or something, since it is just particle board.

BTW- I looked further at the leaking elbow, it was especially leaking where the end of the P trap was going into it. I noticed while making sure it was tight that the straight end of the trap was loose inside the elbow fitting even fully tightened down with the gasket. I took it apart and the gasket fits loosely on the pipe, unlike all the other pieces I had where it was somewhat snug. I have a feeling this one would leak there no matter what I do with it, I'm going to the store to pick up another trap and make sure the gasket actually fits on it correctly.