FloridaOrange said:
We don't have many "wet vent" failures down here. In the 20+ years I've been down here I've never had issues with a water closet not flushing correctly because of a clog in the lavatory. Wet venting is common and correct for this area even if it's not in your area.
Improper order of fixtures or undersizing vents will cause a problem of course but any plumbing that is installed or designed incorrectly will have issues.
Additionally, our plumbing systems have to run at a much higher invert elevation. If we dig too deep we're in water.
And regarding your one fixture failing comment, have you ever used circuit or battery vents? I'm not trying to start a flame war, I really want to know. My experience is strictly limited to Florida. I was taught design by a master plumber originally from OK.
I'll just tell you my history a little with wet vents I've dealt with on the service side of the plumbing in KY and Ohio. And if it is combination waste and vent, it's worse.
On the older buildings where a vent was used as a pathway for the venting of another fixture, at some point that inner diameter can close up, especially galvanized on a lavatory. No two ways around that. Now you have a smaller diameter opening serving two or three fixtures, not one.
When I took my Ohio journeyman's license, I plumbed the isometric drawing to Kentucky codes because I already knew that KY supercedes Ohio codes. The head guy looked at the drawing, shook his head that all that venting isn't necessary but it'll pass.
Short of marrying my cousin, it's nice to know that codes in KY are pretty strict and are enforced under the guidelines of UPC heavily.
When I was a union service plumber in Ohio, that is a drain cleaner's heaven over there for the older homes. Wet venting is to blame. I've been in many discussions with Ohio plumbers trying to figure out why connect the dot plumbing serves such a tremendous benefit over standard "every fixture must have its own drain AND vent"..........all they could come up with is less material cost and less work.
To me that doesn't equate to logical thinking in the game of cards. On a job over at Kahn's they do not vent their fixtures; all of it is standpiped and their thinking is when the drain clogs, it's isolated and you know where the problem lies. WTF? Never mind the gurgling and the slow drains half the time.
The good thing is, in Ohio, they are adhering in the new construction of plumbing to follow the code provisions similar to Ky's and that greatly reduces that issue of relying on a vent pipe that has waste matter travelling through, expecting it NOT to compromise the smooth flow-through that Ky codes offer, along with many others across the United States.
We all know that when a lav drain clogs, and you either unclog it by chemicals or snake.....if that waste matter is hardened up beyond what a cable will completely remove, you'll have another fixture if wet vented compromised heavily by that situation, and no one can see it.
I prefer the codes I was taught as it usually follows most states and is considered the more forgiving plumbing system to run error-free.
The latter has provided me with much work; can't pump blood through a clogged artery.
But honestly, I would like to hear a better answer than less materials, less labor to install. A system with individual vents is code in many states for a reason.