Originally posted by Seschwa:

... Chimneys.

LOL.

I typically build chimneys and then the "vent" is a couple 2m poles with a roof up. On either side of the roof goes one of the X's. Hope that helps.

I've done things like this.

Honestly there are so many ways to vent smoke and deal with this once you get used to the building mechanics that you'll wonder why it was ever an issue for you when you were a noob.