I went to Lowes yesterday and bought all the goodies I needed. I was shocked at how cheap the 1/2" EMT pipe is!! Less than $2 for a ten foot pipe.
I got all the screws, bolts, washers, nuts, L brackets, etc and am ready to go.
Today I put the wood fence posts on the C shaped foundation and yes, it made a huge difference in the feel of the greenhouse. It really locked it down onto the foundation. I highly recommend that step. I used pressure treated 6 foot long fence slats from Lowes (around $2.25 each). I bought 8 of them and cut them to fit. I did have to cut out where the nuts are in their way. You'll see what I mean when you get to that step.
As for the rest of the reinforcements, I have decided to put the roof panels on first. Reason being: once I put the EMT pipe from wall to wall, I will no longer be able to put my ladder in the greenhouse! The pipes will be in the way. So I'm going to put the roof panels on, including caulking them from the outside. I can do that by standing on my ladder with my upper body poking out through the adjacent opening in the root. When that's done, on the same day I will immediately put the pipes up and that'll finish my reinforcements. Then I'll finish the wall panels and can call this project done (at least, for the moment! I still need to contemplate heat and fans!)
