Washer drain backing up

[BEJ99]

Hello, new to this forum!
I'm having problems with my washer not draining and backing up into the room. If I let the washer run on it's owns, it will backup and overflow. If I listen to the water draining and fill up the standpipe and then turnoff the washer, it doesn't overflow and you can here the water drain all at once. Sounds like it does not have enough air.
I found a photo of the plumbing in the wall before it was covered up.
There is a washer and sink on this branch line with a roof vent above. All plumbing is 1-1/2".
There is also a cleanout on the bottom drain next to the dryer vent where I tried adding a AAV about 5' high to see if that would help but it didn't.

Does the vent tie-in from the sink need to be higher than the washer drain? Also, it appears the tee where the sink vent ties in is installed incorrectly?
Any idea on how to correct the problem?

 

[Sylvan]

The Sanitary Tee for the vent is UPSIDE DOWN on the vertical

I would rethink on how many SHORT radius Ells you're using.

 

[Sponsor]

 

[jecottrell]

Washer standpipe and everything downstream needs to be 2". The 1 1/2" is overwhelmed by the flow rate of the washer.

 

[Jeff H Young]

As for the horizonatal on the vent I keep it 6 inch minimum above the standpipe, I think Ive heard that 6 inches above the machine lid was code , but I always went from the stanpipe. Its done and drywalled I dont see a problem it shoulda been 2 inch as well . but clear the drain with a snake. you dont need the aav chuck that in the spare parts box.
I have only a little experiance with undersized drain but think if its plastic and has fall it should keep up. so run that snake my 2 cents

 

[Reach4]

Bad venting alone does not cause slow drains. I think that the vent pipe for the lav should have jogged up, left of the window, to join the main vent line at least 6 inches higher than the standpipe top. But that is not causing your problem.

The upside down venting thru a santee is not going to cause a problem, but it does indicate the person who put the piping in was not that knowledgeable.

How long did this installation accept the WM drainage without backing up? If years, then a cleaning, rather than a rework, is probably all you need. I am not a plumber.

If you had a problem early, or if the problem started right after you got a different WM, then rework would be called for. EDIT: I just noticed that jog around that 4 inch PVC pipe. Horrible. Rework is called for.

Does the sink back up? Is the overflow all suds?