Hi Tim I have a few of the plastic tops that came with some hives I bought from Kelley and I have had a problem with condensation. My solution was to prop the top up a little with an old queen cage. This provided adequate ventilation and solved the problem Frank Hi Tim I have 6 fiber glass bottoms that are about 15 years old and still working great. Frank, thanks for the tip on the top . I needed it. James Peterson, Ph.D.