How to tie a new vent into an existing?

Lockeset

Here's the deal, I am upgrading my tub to a stall shower so I need to upgrade the plumbing from the current 1 1/2" to 2". The existing drain goes horizontally over to the toilet stack, but I am not opening that wall up so I would like to cap that off and run a new drain down to the basement. I would also run a new 2" vent pipe up into the attic where there is an existing 2" vent pipe running horizontally.

I planned on cutting a sanitary Tee into that existing horizontal vent pipe and running the new vent into that.

Will that be OK?

If so, which way I should I face the sanitary Tee? So that the fumes can go up smoothly or so that the rain water can flow down smoothly?

TheEplumber

You can pipe it as you described. you can also vent a shower with 1.5"
When placing vent fittings, think like water. You want to drain back to the drainline.