I was reading about Rose using a swimming pool covers for her hoop house, and I thought I should share the saga of my hoop house with the world.
My hoop house is made of 100% recycled materials, ( except for the cover). It started as........you won't believe this.... 2 discarded trampolines. The trampolines are actually 4 arcs each, which, when put together, form a circle.
The Master put 2 sections of arcs together to make a half circle. He cut the legs off, and inserted them in the ends of the half circle to give it some height. He did this 4 times.
The ribs are PVC, the really cheap kind that is used for sprinkler systems. All the pieces are held together with lengths of top rail from a chain link fence. We used 4 pieces of this, and bolted it all together with carriage bolts. A 2"x 6" board all along on either side of the bottom gives it more rigidity, and provides a place to anchor your covering.
Worth our time to put it together. Very reasonable to build, and it will last forever, I think. At least it will outlast me.
This is great for protecting plants in winter, but it is best as a shade house in summer. We lose more plants in summer heat than we do to winter freezes.