Started a 20x36' hoop house few months back....trying to get the "hoops" built now and get the plastic on before frost. Think we'll make it, but it will be close. Purpose is to extend our gardening season on each end...up until around mid December on the fall side, and start again mid February on the spring side. Won't have any form of heat, so we'll only be growing cooler weather crops like broccoli, lettuces, spinach, carrots, peas, cabbage. Built the outside up with 8" block, then 8" block raised beds around the inside, giving a 32" deep bed (front to back) about waist high (no bending to work the bed). Filled the beds with topsoil, peat, vermiculite, chicken manure mixture. Wife started plants almost before I even got the beds filled... On top the block walls, we built 3' high wood walls. These will eventually have windows that swing out to ventilate the house. There will also be a 4'x4' fan in the back wall to draw air thru. (Salvaged from a commercial greenhouse). Ran 3/4" PVC water line around the bed walls with quick disconnect points to plug in a water hose. Pipe slopes about around to the entry point for drainage in freezing weather.