To vent a shower drain I need to run the vent up a wall across the attic and then back down another wall to connect to the vent stack. The reason is that the vent stack is so close to the edge of the roof that there is no room to tee into it between the roof and the ceiling.

My question is whether it is OK to run a vent pipe up a wall, across the attic and then down another wall so I can get a tee into the vent stack.

I could just put another hole in the roof for just the shower vent, but I hate to do that.

Thanks for any help on this. This is my first post here.

Once you are in the attic you sholud be able to connect to the stack without going back down at all. Do I read you wrong?

Here's another option. Purchase a 3 or 4" Saddle Wye, (see image) drill a hole in the vent stack,, install the wye inverted with the clamps and run the shower vent off that. don't forget to give it 1/4" to the foot slope back to the showe. Good luck, Tom