2” inch vent pipe through top plate?

[Zac_sta]

Doing a kitchen remodel, removed the soffits to reveal they originally ran the vent stack through them to the roof. 2” copper to 3” cast iron. Exterior load bearing wall. Can I replace with 2” PVC and drill through the top plate? Expanding back to 3” before going through the roof. Not going through any studs and plan on placing a 16 gauge strap at the plate to beef it up

 

[wwhitney]

The framing rules for the top plate:

https://up.codes/viewer/california/irc-2018/chapter/3/building-planning#R302.5

And on the size of roof penetrations for vents:

Chapter 31: Vents, 2015 Michigan Residential Code | UpCodes

UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction

up.codes

So if you don't have 1' between the top plate and the roof, the 3" will need to penetrate the top plate.

Cheers, Wayne