Ugh, Forgot Trap Arm - Can this still work?

[BrokeDIYer]

The wife wanted the washer and dryer relocated to an adjacent room with a utility sink installed for Christmas, so I started working on that today. The new laundry room is where the back garage office/mud room was, so drain lines come out through the wall into the garage and then back into the mud room area since the two rooms didn’t quite line up (a wall cavity will be built around the drain lines to hide and protect them. So I started working on extending the washer drain line, adding in a separate drain line for the new sink and made sure to run a dedicated vent line for the washer, all leading back to the main waste stack. 5 pm starts to roll around, kids are on their way home from daycare and I get into a rush to finish up gluing the drain lines before the boys (2 & 4) get home and want to be under foot while I’ve got the back half of the house all tore up. I didn’t realize it at the time, but the extra 4 inch trap arm I cut to come off the trap and into the sanitary tee to the drain and washer vent didn’t get used. Obviously I noticed this after I got everything cleaned up and sat and had dinner with the kids so by then it was way too late. Ignoring the sloppy primer drips because like I said, got rushed got sloppy, how bad is this judging by the photo? Should I plan on cutting the whole trap and sanitary tee area out and starting over to get the trap arm in there? Or because from the sanitary tee to the the actual waste stack there is a 4 foot run of sloped drain line will this still work without the trap arm in place?

Appreciate any advice.

 

[wwhitney]

Since you've created an S trap, and you've also installed the elbow part of the trap backwards with an extra vertical segment, creating an extra deep trap, I think it needs to be redone.

If you have a 2" fitting saver, you could ream out the san-tee side inlet. Otherwise, I suggest two glue couplings, one on the 1-1/2" vent, one on the 2" horizontal drain. That way you don't need any rubber couplings. I'm assuming you can drop the horizontal drain to makeup the last vertical joint.

Cheers, Wayne

 

[Sponsor]

 

[BrokeDIYer]

Since you've created an S trap, and you've also installed the elbow part of the trap backwards with an extra vertical segment, creating an extra deep trap, I think it needs to be redone.

If you have a 2" fitting saver, you could ream out the san-tee side inlet. Otherwise, I suggest two glue couplings, one on the 1-1/2" vent, one on the 2" horizontal drain. That way you don't need any rubber couplings. I'm assuming you can drop the horizontal drain to makeup the last vertical joint.

Cheers, Wayne

Yeah, I really fumbled up that area of the whole thing. I noticed the reverse elbow too after the fact, so the whole connection is a wash. That’s what I get for not paying attention I suppose. I appreciate the feedback and confirmation that I should redo those connections. That’s what I was assuming, but it’s good to get official confirmation. Off to ACE in the morning! Thanks again, cheers.

 

[wwhitney]

Well, I'm not a professional, so I don't know how "official" my comments are. : - ) But if I were a code inspector, I'd write it up as a violation of the minimum distance between the trap weir and the vent take off.

Cheers, Wayne

 

[hj]

WHERE is the "S" trap, and I have OFTEN reversed the elbow. Leave it the way it is.

 

[wwhitney]

OK, you are right about the reversed elbow, thank you for the correction. IPC 1002.4 says the trap seal should be between 2 and 4 inches deep, and it looks like the reversed elbow is not increasing the depth above 4". So that's OK.

And S-trap was the wrong term, I should have said "crown vent". IPC 909.3 says "A vent shall not be installed within two pipe diameters of the trap weir." The OP's picture violates that. I'd like to know more about the reason for that rule, I was obviously conflating it with the prohibition on S traps.

Thanks,
Wayne

 

[Jeff H Young]

yes crown vent wrong term but spot on illegal. We learn to do things a certain way but its been done that way a million times . Not good it might or not be a problem but certainly not code

 

[Reach4]

And S-trap was the wrong term, I should have said "crown vent". IPC 909.3 says "A vent shall not be installed within two pipe diameters of the trap weir." The OP's picture violates that. I'd like to know more about the reason for that rule, I was obviously conflating it with the prohibition on S traps.

I have read various theories on the reason.

If the existing crown vent were to be left in place, I doubt that an actual problem would occur.

 

[BrokeDIYer]

WHERE is the "S" trap, and I have OFTEN reversed the elbow. Leave it the way it is.

Are you inferring to leave the whole thing the way it is or just the trap area? Should I still cut it out to get the trap arm in there? Cold start to the day and decided to start running the new water lines so haven’t made it out yet to the store to pick up the new drain pieces.

 

[wwhitney]

So, based on hj's comments and a little more reading, here's my current thoughts:

- It violates the crown vent rule (minimum distance from trap weir to vent takeoff).
- Many standpipes are installed with the p-trap elbow hub very close to the san-tee hub, which causes that distance to be slightly under the minimum.
- The reversed p-trap elbow isn't a problem in and of itself, but since the spigot end is going directly into the san-tee, the relevant distance is decreased even further below the minimum.
- It will probably work fine.

If it weren't for the 3rd point, I say it would be reasonable to leave it as is, given the 2nd point. But I'm not sure what to suggest.

Cheers, Wayne

 

[Plumber69]

Id leave it. You won't have an issue. It will work perfectly fine. Ive seen way worse and even rhat worked fine

 

[BrokeDIYer]

Sounds

Id leave it. You won't have an issue. It will work perfectly fine. Ive seen way worse and even rhat worked fine

Sounds good. We’ll run it for a little bit while the plumbing is exposed just to make sure it all drains properly anyway, so if I notice anything I know where to go. Thanks all for the input!

 

[Tuttles Revenge]

I would leave it.

I think that the minimum distance rule is likely a lot like a bunch of rules.. "Just the way we've always done it" without it truly having been engineered. Maybe back in the day with cast and steel threaded pipe, there was a good reason.. like the rule for the trap to be a min 6" off the ground so that it could be replaced... totally dumb rule today, but we still have to comply with it.

**In general I like to give 100% code compliant advice.. But there are some portions of the code that are just plain dumb. In cases as this, its good to understand what is non compliant and why its good or bad. Cause and effect. Is this going to become a problem or is it dangerous. No and No.

 

[wwhitney]

The most convincing explanation I ran across for why a crown vent is prohibited is that water falling from the standpipe (in this case) will shoot some water upward out of the downstream side of the trap. That water could carry solids, and if those solids hit the vent takeoff, then could accumulate and eventually foul the vent.

I have no idea if that actually can occur in practice. Maybe it happens more with cast iron or galvanized, which can rust.

Cheers, Wayne