Washing Machine Drain questions

My washing machine currently drains into the sink. I'd much prefer to have a standpipe.

Here's what it looks like behind the wall in the basement. The horizontal copper pipe is the sink drain. The vertical pipe is the vent?


Here's what it looks like from the laundry room side.


I got a lot of good information from this thread. I'd like to add a wye to the PVC portion of the drain. I'd have this run to the left (when looking at it from the basement side) of the water supply pipes, have a p-trap and then go into the laundry room and have a 3' stand pipe for a permanent washing machine drain. I have the following questions:

1. Do I need to add a connection to the vent above the sink connection? I think I do.
2. Is there a maximum length this run can be? It is, however, under 5' across.
3. If I cut the PVC waste pipe, I think it will be rigid, how do I attach the wye if there isn't enough "play" in the pipe to get both slip flanges over the existing pipe?
4. If that is a vent pipe, the rest of the house waste goes through the cast iron pipe below, right? Then waste pipe won't be too nasty when I cut it?

Yes, you do have to vent the new drain. Also, the laundry drain should be 2". It's hard to tell in the picture if that's a 2" drain. May be the copper stub in the bottom of the basement photo is 2".
The stand pipe should be between 18" and 30".
If you don't have enough play to install the wye you can use a shielded band on one side.

Thanks dcelite.
Both the copper and the PVC are 2". The copper reduces to 1.5" above the sink drain. So I'd need to reduce the vent pipe from the laundry drain to 1.5" before adding a wye in the copper. Not quite as simple as I had once believed. Much better to know this before starting!

drain

quote; So I'd need to reduce the vent pipe from the laundry drain to 1.5" before adding a wye in the copper.

I have absolutely no idea what that means. And, the way the drain is run for the sink is more complicated than it should have been if the sink was the only thing connected to that pipe. Your washer connection WILL require a vent, but WHERE it connects to the existing vent will depend on whether there is an additional sink upstairs using that pipe as a drain.

quote; So I'd need to reduce the vent pipe from the laundry drain to 1.5" before adding a wye in the copper.
I have absolutely no idea what that means.

Click to expand...

What I was trying to say is that the pipe is 1.5" diameter above where the sink attaches, while it's 2" diameter below. So I would need 1.5" pipe in addition to 2" pipe. I think it's getting beyond what I'm comfortable doing myself , it's clearly beyond what I can comfortably explain.

I took the picture of what I think this should look like from the other thread and showed what I think needs to get done. Starting from the washing machine, there is a 2" standpipe, a p-trap and a wye which begins the vent (which would be 2" on the two horizontal legs and 1.5" going up). The vent would then be 1.5" pipe and attach to the copper pipe above where the sink comes in with a second wye. There would need to be third wye after the first wye so the new pipe could attach to the waste drain (3rd wye is not in my picture).

but WHERE it connects to the existing vent will depend on whether there is an additional sink upstairs using that pipe as a drain.

Click to expand...

Isn't the laundry room sink using the line as a vent? Why would it be ok for the sink to use its single connection to the line as a vent and the washing machine would require more than just being placed above the laundry room sink connection if there are more fixtures above?

I had incorrectly assumed that since the sink was using that pipe as the vent there wasn't anything above it. I had an assistant run water in an upstairs bathroom, and the "vent" is the waste pipe for the upstairs bathroom.
-where would I need to attach my washing machine vent?
-is the laundry room sink properly vented?

Thanks again,
-Scott