I feel like this could have been written by me, seeing our conditions are more or less similar - some leftovers left by previous house owners as the source materials, possibly not-so-clear idea of what and how to build, and an unreliable result.
Despite what I wrote in the reply to you on my post, I might still set up some sort of a shelter for the plants this summer. I do remember seeing some pretty sturdy pieces of timber in the pile I have, and I can get more from my parents if needed. The only thing I'm missing entirely is glass or plastic for the roof and walls, but that I may be able to buy somewhat cheap if I only use a film rather than solid sheets.
How's your greenhouse project advancing? (Found the newer post, never mind...) I'm probably going to invest in a commercial one as well once I'm done with the more urgent purchases, so I'm eager to hear of your experience if you buy and build one.
RE: The Greenhouse Project