I just use mine to start seedlings in the Spring with little or no heat. Simple "hoop" design (10'x10') with solid north end (w/door). Two-layer inflated plastic cover. I have to replace the outside layer every couple of years. 4"x6" treated sills with one 4"x4"post on the south end, two posts on the north, 2"x8' treated ridge board, 20' 1" schedule "40" pvc pipe hoops. Has worked well for many years for me~ ~~ grnspot110