I plumbed our entire home, all according to code, but now I have a concern. My wife would like her washer and dryer moved to the second floor. Being a good husband I said "no problem". All that is up there, plumbing wise, is her bathroom (vanity sink, toilet, shower) that I dare not enter. The vanity is on one side of the bathroom with the toilet and shower on the other side. Shower (2") and toilet (3") wye together and enter the 4" main stack down to the basement. The vanity has a 1-1/2" drain that wyes into the 3" drain just before everything enters the 4" stack. Now, the only wall (and plumbing) I really have access to without some major demolition is the wall behind the vanity. The washer and dryer would go on the other side of that wall. Is it feasible to tie the washer into the 1-1/2" drain from the vanity and share that drain until it connects to the 3" drain, or am I guaranteed a backup? Thanks in advance.

Not a 100% guarantee of a back up but you upped the odds a great deal, drain should be 2" all the way if not bigger. Any chance you can open just that parts of the wall and get your drain up to 2 or 3"?

Ballengerb1, thanks for the quick response. Just about impossible . Due to the configuration of fittings in a very tight space there is no way to replace the 1-1/2" - 3" wye with a 2" - 3" wye. There is no way to splice in a new wye. I can replace the 1-1/2" drain all they way down to very near the wye with 2" drain but then I would end up with a 2" - 1-1/2" reducer about 8" short of the wye. Would that help or would that effectively not do anything at all?

No that option you described will not help. Here are a few choices including the one you don't want to hear; 1. Tell your wife its impossible due to current plumbing codes. Actually is illegal to tie to 1 1/2" pipe. Leave the machine where it is. 2. Restrict the volume out put of the machine by installing a 2" to 1 1/2" reducer right as the drain exits the machine. This puts some strain on the motor and pump but you are in a bind already. 3. Use an adapter right where the rubber hose enters the 1 1/2" drain to hard connect the pipes, I like this the least because it strains your drains more. We never talked yet about how you planned to get inside the wall to make your connection, what were you thinking. You could just hang the hose over into the tub and blame your wife.

Not sure what I was thinking when I said "no problem dear". I have already ripped out the wall on the other side of the vanity so I could get access to that drain. That wasn't so bad and will be easy to repair. Can't hang the hose over the tub because there is no stationary tub. I am a little confused by your #2 comment about restricting the volume with a 2 - 1-1/2" reducer as the drain exits the machine. Isn't that the same as putting an adapter on the rubber hose and hard connecting to the pipes? Obviously I am missing something here
. One other factoid: there would "only" be about 6 feet of drain before the 1-1/2" hits the 3". Does that help alleviate your concern with the use of an adapter and hard connecting the hose to the drain? Thanks again for your quick and insightful responses.

6' or 6" doesn't matter with water, its pretty much the same back pressure. The restricter at the machine only starins the pump, out a restrictor on a rubber hose and its much more of an issue since the rubber can eventually fail. My 3rd option was my least liked because it puts a strain on the hose. Option 1 is actually the most appropriate and you can blame the codes and laws.

OK, last dumb question. The hose coming out of the washer is already just a 1" hose (perhaps 3/4"). It is the hose that came with the washer. Does that restrict the flow enough to make the 1-1/2" drain adequate or am I just dreaming?

Hi guys...

Traplk... in my area we have been installing washing machine on 1.5" pipes since the beginning of time....;) And we never have any issues!!

There are some of the newer models that some say are too strong for the 1.5" pipe, but I'm here to tell you that we don't seem to be having any problems in my area with them. In fact, the only time I have seen any issues on an 1.5" pipe was when the line was clogged and then I unclogged the drains and they were all set yet again for decades!!

Ballenger means well when he suggests the 2" and most places today are starting to require 2", but not all... like in my state. As far as I know.. they won't be changing the requirement either... at least not for a long time!

I would tell you to stick with the 1.5" pipe... just be sure the pipe coming out of the ptrap is about 24-30" tall and you will be all set! Now... HOW ARE YOU VENTING THIS WASHING MACHINE DRAIN?? The washing machine drain will need its own vent... let me know if you want to discuss more.

Good luck!

MARK

Mark, venting is another issue. I can either "share" the vent with the vanity (within 5') or I can add an AAV right after the P trap. Any recommendations?

Easiest will be to add the AAV... :) Just make sure that it is accessible so you can change it out if it fails to seal years down the road from now.

Best will be to install an 1.5" vent and connect it into the vanity vent at about 42-48" off the finish floor...

Don't forget to install a single lever washing machine valve and actually use it to shut off after each load... that way no surprises down the road with burst hoses, etc. Use SS braided hoses, too!

Good luck!

Mark, our code has called for a 2" drain line and due to occasional back ups they recently considered moving to a 3" drain for washers. What year and code does MA follow where you are?

Hi Bob,

We follow the Massachusetts state plumbing code... 2007.. I think. And, Bob... they ever up a washing machine drain requirement to 3" anywhere in this country and I'll eat the 3" PVC ptrap on video and mail it to you! :) :) :)

Commercial applications still don't even require 3" traps....so pretty darn sure we won't be seeing it any time soon for residential.

Finally, how do you explain fact that we never seem to have issues with 1.5" all throughout my state... unless line is clogged, of course, but then we unclog and all is OK..? I mean, we have some of the oldest plumbing in the country and they aren't even talking about increasing to 2" yet... Hmmm..?

Iamgrowler had told me about the 3" consideration but it did not get any further than a discussion so it won't be in 2009 code when it comes out. Do you folks follow an international code like UPC?

Yeah Iamgrowler mentioned and said it wasn't going any further. Like I said, they don't even require 3" for commercial applications so I don't ever see this happening residentially.

Mass code seems to pretty much follow UPC with exceptions. Now you want to talk a weird code, check out the Maine state code. They follow regular plumbing codes like us, but they will also allow drum traps and NO VENTS on any fixtures if you are within 10 feet of a vent stack... now that's nuts!

Thanks Bob...

MARK

Saw the guys on This Old House removing a drum trap last night. I'd just run the other way.

Although I recommend 2" for a washer and 3" if both the kitchen and washer are on the same branch my own washer in my 50's house has been 1 1/2" for over 50 years. Of course I had to make a solid connection between the washer hose and the stand pipe to prevent backups.
Like Mark sez, Go with it! Good luck, Tom

I just want to confirm: many old houses in my area run on 1 1/2" drains even with today's high output washing machines. So, I wouldn't worry too much about it...

Thanks to all for the helpful and intelligent responses. This is a great board with some outstanding folks. I am going to proceed with caution with the 1-1/2" drain. Plumbing in the hot and cold water and putting in the standpipe will be relatively simple tasks. Worst case is that it doesn't work and I have to move the washer back downstairs. At least I can tell my wife I tried. Thanks again.

We are all glad to help! Remember to use that single lever shutoff if you can and finally as a last note, I advice all homeowners to shut off the main water shutoff to the house before going on vacations or long weekends if possible. This way, no surprises when you come home! Just FYI.

Good luck!

MARK