For a cheap & nasty eBay greenhouse, it lasted six years without fuss until some of the top polycarbonate split and blew out in some wind. Being from offshore, none of the replacement painels were wide enough, so I’ve had to add a pine frame a little wider than the original and add slots to it. It was done with half lap joins, glued and dowelled at the top and screwed at the bottom so you could remove the bottom rail and slide the panels in. Then all the fixed parts were screwed through the original greenhouse frame (aluminium).
Two coats of marine grade cedar stain and it’s looking quite swanky.