Hi Jeff As I mentioned in our private emails, my location is also VERY windy...I'm surrounded by empty farm fields in the winter and as I live quite close to Lake Huron, we get very intense storms from the North. Thus far, I haven't had my pool cover budge an inch. We attached it with tarp clips to the bottom edge of the greenhouse (which is wood), screwing the tarpclips directly to the wood using large washers. The vertical edges of the cover were screwed to the greenhouse, using 1"x1/2" strips of wood. We cut a square hole in the roof section, just large enough to accomodate my automatic venting window. We had intended to use allweather duct tape to seal around the edges of the window, in case of flapping from the wind, but never got around to it and the wind hasn't seemed to catch it all. I'm going to try to send you some pictures. My computer won't allow me to post photos to a photo hosting website (gggrrrr) but I can email you some privately. I have a heater in my greenhouse now but last year I didn't and I built a little hoophouse inside to keep my seedlings and cuttings warm at night. The hoops were built of flexible conduit from Home Depot which were covered with plastic sheeting. I had heat mats inside under the trays, which were sitting on a sheet of extruded foam insulation and that was enough to keep things from from getting too cold. I pulled the plastic sheet over at night and opened it during the day when the sun naturally heated the glass building to 80*. If it was extra cold at night, I also threw a blanket over the whole thing.

karenrei, I don't have a hoophouse, each wall and the roof are totally seperate segments as to R value, covering etc. stressbaby nailed it on the head on this thread http://forums2.gardenweb.com/forums/load/strucs/msg0909104730738.html and I am surprised that thread did not get more input. Identify areas where improvement can be made and fix them. Then look at the whole structure again and work out where the "new hole" is. On the thread about the polystyrene sheets, http://forums2.gardenweb.com/forums/load/strucs/msg081128491250.html I tried to point out that adding an R3 insulation to one wall was great, bumping it up to R6 may be a waste of money because there may be another place you could put some R3. Yes, In retrospect my south roof (and sorry to use trade names but people can look it up and understand it better) should have been Tufflite IV outer, pool cover and then Tufflite infrared on the inside. A nice sandwich and cheaper and easier to install then polycarbonate triple wall. Yes I know polycarbonate triple wall will last longer but, it is also very expensive. I had a standard double poly inflated south roof so I gained some insulation advantage but all of that insulation was lost by a breach of the outer layer. (see my rant on this thread) http://forums2.gardenweb.com/forums/load/strucs/msg0409365924489.html OK, so I know I am going to lose light on the south roof because of this sandwich but I am going to get a boost in insulation, and because of the bubble wrap sandwich I am also going to get some protection from damage. The sections would be 2ft by 8ft and if I had a breach of the outer skin then my south roof loses 1/12 of its R value not 100%. Next, as in reducing light transmission, as you say most of the light in spring is through the south wall, so a reduction in light transmission in early spring of say 15% from the south roof is still a loss but a small loss as not much of the total is coming in that way. ""any areas that don't get much sunlight being as heavily insulated as you can with opaque (preferably reflective, in my opinion) insulation."" North wall is solid and painted white inside (reflective). Half the north roof is solid. Changes to my configuration next spring? 1, Shade cloth hung vertically inside about a foot from the south side to reduce the tendency of young plants to grow towards the south side but as the shade cloth is on the inside it will block light to the plants but still contribute to raising the air temperature in the greenhouse. 2, Wait until the corn and bean crop is harvested and there is snow on the ground and then set fire to my old barn to the south where the shingles that hit my greenhouse in high winds come from. (insurance company please note, that was a light hearted attempt at humour.) Umm... on second thoughts, I will insure my greenhouse! :)

Just to echo Scott - I've heard people have had success with solar pool cover rings and they might be the ticket for you. Anything else that will help stop evaporation will be helpful for trapping heat.

My advice is to wait. Yes it will get in the way and can cause an uneven curing. It can slap against the walls as wind pushes it. Stay out of the pool until it can be balanced and the plaster finish has a chance to harden. It's an exciting time and one that has been waited for with great anticipation but please be patient just a little longer. Scott