I recommend leaving some sort of hole or latch at the top here. After building this green house I noticed that many bees, butterflies and other insects came in to do their work… But they got trapped inside….. Even though all the doors were open, all of the bugs got trapped at the top. Aparently bees and insects like to fly up……. If I were to make this green house differently, I would add some sort of hatch they could fly out of, at the top.