Is there also a clean out at ground level near the p trap you speak of? Unless the roof is unusually short, vents through the roof usually don’t cause an issue.
Hey, new guy here, and first post. I should probably check for an intro section but I just wanted to throw a pic of one the new colors for the 5 drawer carts. I’m working on getting her loaded now, only mod was the 10” pneumatic casters, but I’m sure there will be more to come.