I want to add a PVC standpipe for the washing machine and have the 2" PVC trap drain into an existing 2" copper DWV pipe. Would like to tap into the copper DWV pipe by cutting out a segment and putting in a PVC sanitary tee. I was hoping to use a shielded coupling to connect the top and bottom side of the tee to the copper piping with a PVC spacer, but code provides the following:

"705.18 Joints between different materials. Joints between different piping materials shall be made with a mechanical joint of the compression or mechanical-sealing type . . . or as required by sections 705.18.1 through 05.18.7. . ."

"705.18.4 Plastic pipe or tubing to other piping material. Joints between different types of plastic type or between plastic pipe and other piping material shall be made with an approved adapter fitting. Joints between plastic pipe and cast iron hub pipe shall be made by a caulked joint or a mechanical compression joint."

Question: Does this mean that I cannot use a mechanical-sealing type coupling to go from copper to PVC, or is 705.18.4 just providing an alternative to 705.18? Was hoping I could avoid using copper fittings, since they are expensive and I probably would need to buy pipe and don't want to spend $100 for 10 ft, when I only need a couple feet.

Thoughts would be appreciated. Thanks!

I think you can put a threaded fitting on the end of the copper pipe and do the plumbing from that point in PVC. The threaded connection is the mechanical one. Even if you change some of the copper fittings to PVC, it would still be cheaper.

Why not to ad DWV sanitery tee, trap and stand pipe - all in copper , and make entire installation uniform ?

The way I read that is:

A mechanical joint of the compression or mechanical-sealing type (Fernco).. .

or
as required by sections 705.18.1 through 05.18.7. (a threaded adapter)

Don't see a problem using Fernco shielded couplings.

HI again all:

AMWASH:

HKSTROUD is correct here... as far as I know a shielded clamp such as the mission or proflex clamp is permissible everywhere for what you are talking about... see pics.

You cannot use fernco style clamps (no shield... last pic.)

Here, the mission or proflex style clamp you want is a BANDED reducing clamp that acommodates the difference in pipe size from 2" pvc to 2" copper pipe.

To be sure that this is allowed in your area, just call the local plumbing inspector and ask him (or next town over...;) ) if you can use shielded clamps to transition from 2" copper to 2" pvc pipe. I am confident that he will say yes.

You said, " Would like to tap into the copper DWV pipe by cutting out a segment"... NOTE HERE, that when cutting into the copper pipe you want to support the pipe well so when finish cutting into it you don't disturb anything above it... ok?

You will also need a VENT for this installation!!. If vents are in the basement from a toilet or sink you may be able to connect into them (1.5" vent needed for washing machine)... OR you may be able to use a mechanical vent (an AAV.. air admittance valve... see pic.).. but again , that will depend on local codes in your area (let me know if need more info. On this).

I left a pic. Showing how these vents connect into a trap situation (picture is of a sink, but you get the idea)... but I would install my AAV a bit higher.

Finally, you want to add a full size cleanout just after your sanitary tee connection, and you want the standpipe out of the trap to be about 30" or so...

Let us know what you think AMWASH... ok?

MARK

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Thanks all! Very helpful.

Mark, that's exactly what I was expecting to do, except that I hadn't planned on a cleanout.

Here is a before and after (excuse the pre-school quality of the drawings). Wouldn't touch the main soil stack (the dark blue pipe). The drain/vent that I would connect into is the light green one--2 inch copper. I would tap into it a few inches below the entry point for the laundry tub drain. I would back vent the standpipe as indicated after the standpipe trap. (The existing laundry tub does not appear to be separately vented, except as shown). Would tap off the supply lines up top to add new faucets for the laundry machine above the standpipe. (The standpipe trap will be a couple inches above the floor, passing through a non-load bearing stud--despite what it looks like in the drawing). What do you think?

Where would the clean out go? Down stream of the trap or upstream?

Milo, the problem with trying to use copper for the entire thing is that it would push my material costs close to $200--way too much for my budget, and a simple hand torch probably would not be sufficient to do the soldering.

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Sure... Cost of copper is way up these days... Also, nice drawing...

Mark gave you a good, comprehensive, answer. I personally think that Mission coupling will serve you better rather than Flex-Seal coupling. Flex-Seal coupling is a great invention and "live saver", but for this application, I think, it is way too flexible. It will give away a bit. Mission coupling will hold the horizontal arm much steadier. You can actually purchase Mission coupling that is specifically sized to go from DWV to plastic.

Also, pay attention to the 30" tall stand pipe. It is pretty important detail. It needs that height to absorb all the water your washer will discharge.

One small detail: We always try to avoid connecting washer drain to kitchen drain. Kitchen drain is the dirtiest, and most clogged up, drain in your house. Washer needs clean, unobstructed, drain that will allow large amount of water to freely flow away. Kitchen drains are almost always somewhat enclosed and will slow down the drainage process. Back-ups may occur.

Let us know how you did ! Good luck !

Y'know... I was wondering if that was a drain pipe to the kitchen sink. Milo is correct about avoiding kitchen sink drain lines to connect into. However, a laundry tub has already been connected improperly (and unvented)...

Amwash... what size is the pipe going to the laundry tub... just curious here.. Is the pipe off the 2" copper pipe...1.5" or 2"..

Wondering if you should repipe this so that you can install the washing machine drain and vent lines, and also repipe the laundry tub so it gets a vent, too...?? If laundry tub has no vent, most likely when you use the kitchen sink drain you may be siphoning the trap and allowing sewer gasses into the house.

Further wondering if it is possible to connect into the main cast iron stack you showed in blue.. Not to cause you more work here by any means... just wondering if not a bad idea to pipe all this, vent all this and be done with it forever!

Let us all know what you think here... MARK

PS. The cleanout would go downstream of the trap just before the pipe connects into the 2" copper drain line.

.

It's a tricky read, but the codes are calling out for a shielded coupling.

The correct shielded coupling for joining 2" copper to 2" plastic or steel is a Proflex, Mission or Fernco CK-22.

Finaly two questions: I can either run the standpipe drain horizontally to the stack on the same level (the pink line) or through the floor to meet the copper pipe before it connects to the cast iron stack. Is one better than the other?

Also, if I go the later route, it would be much easier to connect to the copper pipe by cutting out a section of the copper pipe that is at a 45 degree angle, insert a sanitary tee on the 45 degree angle, and connect that to the drain from the standpipe. I can't fit a wye on its back on the 45 degree angle because there is a joist in the way. Is a tee on a 45 degree angle just as bad as a tee flat on its back? (Local code does not talk about "vertical to vertical" changes in direction, if this would qualify). The other option is to put a wye or a tee where the picture below shows, in place of the 90 degree elbow that is there (this will be a little bit more of a challenge, since I will only have a couple inch stub of the copper pipe coming out of the cast iron stack wye to which I would attach the proflex coupling--I would hesitate to pull that stub out completely and try to fit the pvc directly in the cast iron hub with a donut, since it sounds like the tolerances are very unforgiving for making a good seal that way.)

Thanks so much for any and all thoughts!

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