I did one last fall which is working fine (I put lettuce in on 27 Feb and it is growing fine; I plan to pick some next week). Mine is 8x12 (if I did it again, would go 12x16). Made a perimeter frame of 2x6. Used 1 inch pvc pipe for hoops[if you can not find 20' lengths, get 2 10's & join in the middle]. You need some sort of ridge board-can either make it from a 2x4 or use 3/4 pvc joined with straight connectors and cement and tied to the hoops with cut up strips of bicycle tubes. Attached the pvc to the inside of the frame with pipe clamps held on with a sheetrock screw. Made some end walls from 2x3-nothing fancy, but just enough to affix my strapping which held on the plastic, have an entrance & venting for March & April. Plastic was held down with strapping screwed to the perimeter frame with sheet rock screws. My experience with a small house like this is that good end wall vents will probably take you through the end of april. (I have a fan but have not yet used it. What I did is screw some strapping on the hoops about three feet up. When it gets too hot for the vents, I can lift the sides up and tie them to the strapping screwed on to the hoops. I plan to put tomatoes out @ 15 April (cover them with remay cloth for a few weeks). My first frost is usually during the first few weeks of October; I suspect I can keep tomatoes going until mid December and lettuce and chard well into January. Actually, my lettuce survived throughout the winter (lowest temp was -4) under remay; no heat at all. There are some fairly good ideas in Eliot Coleman, The New Organic Grower. Also, if I remember correctly, UNH has done a lot of research on this. They call them high tunnels. Bill McKay in E. Massachusetts >Looking for idea's > >Want to install a temp greenhouse over the top of my normal >growing area. Concept is to extend growing season spring and >fall. > >Problem trying to figure out how to roll 16 ft wide plastic over the >top, tie it off, keep it secure, then remove after it gets too hot. > >Any suggestions would be aprricated >Byron > Get Your Private, Free Email at http://www.hotmail.com