How Not to do Plumbing Vents

Yes, it's another one of those posts.

It describes one of those things that make you go, "Hmmm?"

Or one of those pictures on This Old House's Home Inspection Nightmares gallery.

The Wisconsin Department of Health Services has a nice piece on the dangers of sewer gas.  It should be required reading if you're planning to mess about with your plumbing vents...

Remember when I replaced the wax ring on the toilet because there was a foul odor in the Study Bath?

Well, it helped for a while, but eventually the odor came back.  Now that we've demolished the attic, I know why...

See the pipe up against the brick in the attached picture?  It's above the left-most leg of the telescope.

That's the plumbing vent for the study bath.  It comes up from the first floor behind the curved wall in the Music Room.  Then up through the corner of the closet in Little Man's bedroom.  Then up through the attic floor in the picture.

You might think that it passes through the insulation and out through the roof deck.

But you'd be wrong.

Instead it goes through the insulation and stops.

Inside the house.

And there's a rag stuffed in the end of the pipe.

That means that it's not venting properly.  So when it needs to let air in, it creates a vacuum that sucks the water out of the traps in the bathroom and lets the sewer gas escape into the room.  And when it needs to let sewer gas out, it ends up inside in the attic.

Loss of consciousness and death.  Lovely.

Flammable and highly explosive.  Brilliant.

Needless to say, the new plumbing vents in the attic solve this once and for all.