Ok here is the debate. I was telling with my father in law about installin our stovepipe/chimney. I told him what i had read here about the crimped end down to prevent stuff from leaking out plus the benefit i woudl see come cleaning time. He says the crimped end should be up because if the crimped end is down smoke in theory could escape the stove pipe on the way up. I mentioned sealining each joint to prevent that but it did little to change his opinion. What do you knowledgeable folks have to say about it