Attic vent connection from basement

[CPinCT]

I am connecting a basement bathroom vent to an existing copper vent in my attic. In a tight space in the attic there is a 2" piece of copper that runs horizontally for a few feet before connecting to a 3" vent that goes through the roof. I ran a 2" PVC vent from the basement intending to connect to the horizontal copper piece with a rubber tee. However, the only place I could get the vent up through the wall left me with only 2" from the PVC to the horizontal piece of copper that I want to tie into. There is not enough room to add the fittings in between.

The simplest thing I can think to do is to cut the horizontal copper and insert the rubber T on its back. From there I would go up several inches with PVC, add a 90 toward my new vent, then travel several more inches where it would connect with another 90. This would create an upside down U.

Is that OK to do?

 

[hj]

The majority of inspectors would have a problem with it, because the general rule is that vents have to flow upward. Your situation is in the gray area between what is "legal" and what would work. But there are probably other ways to make the connecion, you just don't know them.

 

[Sponsor]

 

[CPinCT]

Here is what I have. The roof rafters are a few inches above the top of the picture. I might be able to cut the 3" but I feel much more comfortable cutting the 2" given the tightness of the space.

 

[Cacher_Chick]

Perhaps you can get a 1/16th bend or 1/8th bend in low enough to tee directly into the copper?