[masraum]

Originally Posted by dad911

IMHO plumber is taking the easy way out with an AAV. We've used them in a basement, but on the second floor he should either cut in a new roof boot or tie into an existing vent. Minimally have him put the AAV in the accessible attic space and not a vent in the wall.

https://terrylove.com/forums/index.php?threads/toto-wall-hung-outlet-pipe-slope.69960/

I'll check out the other stuff that you're talking about.

We don't really want to have another perforation on the roof if we can get around it. It's on the front of the house and will be highly visible. Running the line around to the existing vent will also be a big run that'll likely be a pain in the rear. Yes, the AAV would be in accessible attic space.

Originally Posted by ben parrish

The Studor Vent will work as the existing stack will stay in place. The AAV vent only opens when a vacuum happens but the drain line must also have a live vent to allow air to “push” ahead of the water. The toilet will not flush properly without a live vent.
How far is the new toilet from the old? If the drain line is 3”, you can go within 6’ and be within code...if a 4” drains line is installed, you are good up to 10’. Btw, the AAV valve mus not be buried in a wall and must be accessible for service and repair.

Yes, there is a live vent at the existing toilet that I assume would stay in place, and yes, the line would be 3". I think the flange to flange distance between new and old toilets would be 18-19'.

Yep, the AAV would be in accessible attic space.

Originally Posted by ben parrish

The 2x4’s with the “air gap” are not really that strong. To give the proper strength, sandwich a 3”4 strip of plywood between the 2x’s and glue and screw. This will give you a much sturdier support and a true beam.

Yes, I was surprised to see the air gap in those 2x4s myself. I realized that our plan is to put the wall back in place, so I should be able to put a new reinforcement in that is sturdy, plus I'll have the wall there supporting the beam. I suspect the beam was added when the original wall was removed.