We sealed our cabinet up pretty well with caulk when we built it. You want it sealed well to keep fumes out. We nixed the hole in the floor, and put a vented door on the outside instead. Chris found a hotrod shop that would cut the vents for us. We were able to reuse our chimney vent with a little repair, but you could use something else to build it, like aluminum. Haven't had any issues with ours, but you live in a hotter climate than we do, so maybe a 12v
fan is a good idea for you...