Wet Vent Bathroom and Washing Machine

[Woodm]

I would like to add a clothes washer drain to an existing cellar bath room drain per Maine UPC. The bath room is currently plumbed under the cement floor with a 3” wet vent serving a toilet, shower stall and a lavatory sink, the 3” drain runs into a sump which is vented with a 2” vent line and is near the outlet to the septic tank. The sump pumps above the septic tank outlet and gravity drains from there.

I have attached a schematic which shows the original bath plumbing with the proposed Washer standpipe plumbed into the 2” sink drain using a 2” double sanitary tee with an additional vent line from the sump installed in the bathroom ceiling. The washer hookup would extend 2 1/2ft in the bath wall and come out in the adjacent laundry room with a 2” ptrap and standpipe.

Is this correct?

What is the minimum vent pipe diameter for vent to be installed in the ceiling?

Thank You



Thanks

 

[Jeff H Young]

2 inch

 

[Sponsor]

 

[wwhitney]

Your existing layout shows a violation of UPC 908.2.4 on the horizontal wet vent. The WC is supposed to join downstream of everything else, in particular the shower.

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As to the washer standpipe, if you join its drain to the sink drain you disrupt the horizontal wet venting of the bathroom and would need to dry vent the shower and WC. So to maintain the horizontal wet vent on the bathroom, you would need to route the washer standpipe drain to join downstream of all the bathroom fixtures. [Depending on the framing and the sump access, it might be possible to run the washer standpipe drain above the slab straight to the sump.]

As for vent sizing, the lav dry vent needs to be 2" because it is wet venting the WC. A dry vent serving only the laundry standpipe can be 1.5".

Cheers, Wayne

 

[John Gayewski]

Did do what Wayne said. There's not much you can do about the existing incorrect wet vent layout, but you do need to drain the washer separately from the bathroom group fixtures.

 

[Woodm]

Thank you for your replies. So, I guess I'll be hiring a plumber to run a direct line to the sump. It looks like it can be run in the wall. But I'm not comfortable cutting into the sump. The issue with the existing layout is my error, the actual piping is under the ground and the shower and toilet are close enough that it could be connected in either order from where I'm looking.

Again Thank you for all your help.

 

[Jeff H Young]

I suppose there could be a question on the "Lavsink" whether it could be considered a laundry sink or a Lav part of bathroom group. I'd forgive it either way but if I was in a tough jurisdiction I might sweat a bit.