Update: I am busy reading and studying the long blog as the greenhouse is on it's way. I am amazed that one person wrote in such great detail about the construction, took photos, and then takes the time to answer blog questions about it. And she is so nice about it! I am up to part 3 and getting a lot of good hints. I am taking notes along the way with references to blog part and page numbers of the information I think might come in handy later. I will copy and paste it here as sort of an Index to the comprehensive blog.. There is a LOT of great information in there both from the Blogger as well as the comments and hints.
I've decided we are going to try to protect the cheap panels the best we can with the $7 UV spray. I don't need the shade protection via Shade Cloth in our yard as much as I just need to preserve the panels. If it can protect artwork, I ASSume it will help with polycarbonate. The panels with the kit last about 4 years according to the Blogger. The cost to replace them with good quality panels is around $500 from greenhouse supply companies. IDK if that is worth it for a $600 greenhouse? Harbor Freight has replacements for $135. I am thinking, with a little UV spray on them I might be able to make them last 10 years in my shady yard.
