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! :)

pushindirt: If you are referring to the bubble, if you buy it in 2 ft. widths, it should fit between the aluminum polybars on most standard aluminum & polycarb GH's. If you cut a piece the size of the polycarb panel on all or just one of your roof vents, it should allow the vent(s) to operate. If not, the heat shrink film would certainly not overweigh them. You could also cut out only the bottom and sides of a pool cover where it covers the vents, as many people do with sunshades. Double faced tape or velcro might work to hold the cover onto the vent sash, to prevent it from blowing back, leaving the vent uncovered when you don't want it to be. Solar pool covers are far heavier than any bubble wrap and also have bubbles, but much smaller. However, in larger sizes, they can be quite heavy and as another poster noted, getting a large one up can be a real challenge. Our's was so heavy, we cut it into two sections and overlapped them on the top of the GH. The wind took one off shortly after we put them on last month, which fortunately taught us a lesson before it became too cold to work outdoors. I bought some nylon webbing and tied it to some bungee cords that are connected at the base on either side of the GH. It goes over the top and holds the overlapped covers down securely, yet gives just enough as to not put undue pressure on the polycarb. We also used a strong braided nylon rope to wrap around the GH from one side of the door and around, to the other. It's holding the cover tightly against the kneewall and has proved a far better solution than laying bricks and timbers along the bottom as we did last year. We learn as we go.

I have used hairy vetch once; I had to order it from a farm supply company and it came in large quantity, like per-pound. I used it in a meadow that we were transitioning from scrub/weeds to wildflower borders surrounding turf grass. It worked and boosted the nitrogen quotient significantly, but I gotta tell you, it was a hairy beast to till under (though to be fair, I was working a large area as opposed to a contained bed). The thing I personally love about raised beds in the first place is avoiding work like double-digging, so I have an alternate suggestion. In late winter, a couple of weeks before spring breaks where you are, cover each of your beds with heavy duty black plastic, weighted down with whatever you have on hand, rocks, bricks, etc. Leave it on there for a couple of weeks and it will do two things 1) discourage weed seeds from germinating, and 2) warm that soil right up! When it's time to plant your spring crops in that bed you can either cut holes in it and pop the seedlings right in, or remove it altogether.

Hi Matt We, too, used solarcovers.com and were extremely pleased w/ both the quick service and the quality of the product. We ordered our cover late on a Wed eve and received it on Fri of the same week! We bought the clear 16 ml (or was it 18ml?) and it works great. We went ahead and purchased a Rocky's roller the next week and have been happy w/ that, too. Our water was delivered at about 55 degrees (not the 75 as claimed) and it HURT! We just used the cover to bring the temp up as our heater had not been hooked up at that time; water shot up to 77 w/i days. Due to a few delays in the project, we had to shut down our pool in Oct so no more swimming for us for now. Feel free to check out our pics, though, at 'attempting to post joanneswimsct pics' to see what we'll use in addition to our solar cover when we get things back up and running...! joanneswimsct