Re: Combining Batroom Exhasut Vent w/Existing Vent
You definitely don't want to tie the two together, aside from the toxic gases coming into the room you'll also be getting sewer odors. What you can do is vent the bath through it's own roof penetration, the only caveat to this is if you live in cold climates the vertical vent could be prone to icing and freezing from the damp air being vented from the bathroom or possibly being covered by snow.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!