I am remodeling our 2nd floor bathroom. I have a permit so work will be inspected. I have all drain lines planned out and am happy with the layout. The 3" vertical drain line in the wall of the bathroom is part of the old work and cannot be moved or accessed (including the 90 long run at the top of the vertical drain). It will serve as the main drain for the water closet, shower and tub.
1. The lavs are connected to another branch with its own venting so they are ommitted from this layout.
2. All 90's in the layout are long run 90's.
3. I am under the IPC and local code does not modify the IPC materially w/r/t venting.
4. Assume the drain layout is fixed, please.
WC - 1.6 gpf (2 dfu's)
SH - 11.6 gpm (1.6 gpm shower head and 4, 2.5 gpm body sprays) (3 dfu's)
BT - (2 dfu's)
I have come to the conclusion that I have to vent each fixture independently based on my drain layout. I decided this because of the following:
1. I cannot use the 2" vent off the WC to wet vent the shower and tub.
2. If use a wet vent to vent both the shower and tub, I would have to go up to a 3" vent (because I'd be wet venting a total of 5 dfu's). The wall is 2x4, and I cannot run a 3" vent in a 2" wall.
3. I cannot tie the tub into the dry vent for the KS and DW because then the KS would be wet vented which I believe is not to code. Also, the DW is 2 dfu's and the KS is 2 dfu's, so the 2" vent would have to be upsized to a 3".
I am ok with venting like this, but I'm looking for suggestions two things:
1. Alternate venting solutions
2. Advice on how to tie the vents in once I'm in the attic (or can I tie some of them in 6" above the flood level of the tub?