this is my portable green house. it is the third revision. i do not show the removable hitch i made to pull it with the lawn tractor. i set it up on 3 ton jack stands with 18x18 patio blocks under them. walls are insulate. the panels i made pocket hole joined frames. They are covered with 6mil UV resistant poly. poly is stretched tight and taped closed to seal it. anywhere a panel touches i have a layer of amaflex tape to serve as a gasket, it is about a 1/16th thich compressed and waterproof. the roof panels are screwed in to joists the same as the sides. but make sure you take care to seal the seams and screw holes for more water tightness. The auto vents are green house solar vents. so far there is no condensation and it is holding up really good. working on a solar water heater now to remove the load off of the solar system.