I'm not a plumber. I heard a builder say in an exasperated way, "Even though there is no reason for a kitchen sink to be vented, code says it has to be vented, and the code enforcer will agree with you, but it still has to be vented, even though you have to run a pipe up 20' to the roof." It was a comment made as an example, related to the over reaching of government in our day to day lives. Being a curious person I was wondering if the statement was valid, so I thought I would ask the forum. I don't have an ax to grind.