After a year of using my greenhouse as nothing more than an expensive seed starter, I want to learn about getting an earlier start and extending the season longer. From what I have read, this will entail sealing any leaks, insulating, an alternative heat source and a few other things, but before I begin, I realize I have one major obstacle which if I can't rectify is going to put a real crimp in my efforts.\n\nWe bought and assembled a Sunshine Gardenhouse Mt. Rainier 8 x 16 redwood and double wall polycarbonate greenhouse. Today, I was looking at some YouTube vids and learned that if the ends of the polycarbonate panels are not sealed off, there is no air lock and therefore no dead space to help the insulating factor. My problem is it appears my polycarbonate panels are "floating" (for expansion/contraction) in the redwood frames, but they were never sealed at the ends! (Seems like a poor design to me.) \n\nMy question...if I spend a small fortune on silicone caulking (most of which I'll wind up wearing like my friend [USER=1586]@tbendl[/USER] ) and I caulk around each panel both inside and outside, will the silicone caulking allow for enough expansion/contraction AND act as a seal to keep dead air in the panels? Seams to me it would, but want to bounce it off some others first. Thanks!