Nice construction and I can see some real potential with the design. But I'm wondering about how efficient this would be during cold weather. How will the single thickness plastic sheeting retain heat during the overnight hours? Double wall polycarbonate panels would be a tremendous improvement - although more costly. Can't tell from the finished photo, but the bottom appears to be open and exposed to drafts. Shouldn't there be another sheet of polyethylene - or an insulating panel? Or, are you concerned with water drainage?

soycandle, I might not even ought to post because I am not in your climate zone (I am in zone 8B) and have no experience with the type of winter you have, but...that said... I have had a portable greenhouse for 5 years. Its the same basic type as yours, from a different company. Mine is called a "Groenhaus" and it came from a company in I believe Norway (may have been Sweden, but its one of the Scandanavian countries where they have an actual winter with snow, ice and wind.) Mine has a steel frame in a hex design, air vents, and zipper door. Its made of 12 mil woven poly fabric, and conducts about 83% of available sunlight. The cover is thick and insulates very well. I myself live in Northern Florida where there is no snow, no ice, but it does occasionally get down to 20F once or twice a winter. I have had GREAT SUCCESS with my portable greenhouse. I have used it to overwinter tropical plants that were containerized (plants like heliconias, Ti leaves, gingers, aroids like anthuriums, orchids, bromeliads....) I have also used it one winter to cover a 6 x 6 raised pond that had tropical water lilies in it, I also stacked in a bunch of containerized plants in with the pond and they loved the humidity...currently, I leave the base of the frame on the ground year round, surrounding an outdoor inground planting of tropical plants that would freeze even in our relatively mild winters (Alpinia purpurata, Heliconia, bromelaids, Ti leaves, birdsnest fern, etc) and erect the cover over the bed in winter, then take it off in spring. These little portables work GREAT. All you need is to put a portable ceramic space heater (the kind with a thermostat) inside the grennhouse. For your size house, 6 x 8, one 5120 BTU heater will make it toasty for all your stuff. I have the type that you can set the temp, the range is 55,60,65,70,75 and 80. The heater goes on and off automatically to keep the GH at the temp you choose. The heater has a built in fan and blows warm air out, and it oscilates to help distribute the heated air more evenly. Its also helpful to have a small oscillating fan that you can hang from the frame in the roof to circulate air and heat. This cuts down on consolidation and also on algal growth and pests. I see you are in zone 5...it will of course take you more electricity usage to heat your greenhouse than it does me, but it also depends on what you are growing....I keep mine at a minimum of 60F, but the plants you are growing may only need above 32, or the 40-50 range. I would think you could go on and set the thing up and start using it now. The only advice I would offer additionally is, if your winter storms include WINDY CONDITIONS, be certain you use any tie down apparatus (stakes, guy wires etc) that they offered you. Without them you run a risk of the whole thing blowing over in a high wind. I think of mine as a big, almost clear TENT that my plants are camping out in.

I ALWAYS play nice (well, at least MOST of the time!!!) Okay, pictures have been taken - but not DL'd to computer yet (I'm surfing @ poolside via WiFi... Oh the SACRIFICES I have to make! ;-) I think I've been inspired to post an addendum to my "Garden Page" (you can get there from my webpage, linked below). I haven't done it yet, but I'll try to post my GH erection efforts "Step-By-Step." They won't be as good as conifers'/Dax's pictorial, but I'll do my best (Gotta "Give Back to the Community," right?!!) I think the wood-cutting is still a "hair" off, but the 'errors' will be put on the back-side (next to a fence, where no one will ever walk / have an opportunity to bend the aluminum base). Or maybe I'll add some skinny/lath/shim kinda material for the Too hot to dig up veggies right now, so I'll postpone that 'til early evening (or early tomorrow morning). I'll probably move my "boring observations" to the webpage (When I start it!). I'll just make note, on here, when I post updates - so I won't bore everyone with my long-winded commentary!!! Of course, I'm *sure* I'll have more questions as I go through this - and I *will* post those questions here! And I just thought of another Q: Should I paint the RW base before I assemble it? If so, white (for reflective qualities)? Or black (for heat-sinking)??? Or should I just hold off on that altogether (bearing in mind that it'll be easier to paint BEFORE I assemble it)??? Any thoughts...??? Thanks - AGAIN - for all the support, insight and advice! And thanks - in advance - for enduring my upcoming questions!!! You guys ROCK!!! -Nancy Here is a link that might be useful: IMQTPI's Garden Page (I'll update it soon!!!)

I was surprised to see my old post back in play after 2 years, but as it is, I'll report. The Sterling outperformed expectations and contrary to some cautions about having such a powerful unit, it maintained my desired 72 deg. temp throughout our bitter cold winter for a fairly cheap cost and if it turned on/off more than a smaller one might have, thermocouplers are cheap and should be replaced regularly in any case. Mainly, it kept the GH warm, and I reared a lot of delicate tropical fish in it, while the bitter winds blew. We calculated that it added no more than $300.00 to our heating bills for the entire season and possibly less, as my husband also ran a gas heater in the tractor shed for most of January, and it is not only far larger than the GH, it's also not as well insulated. He plans to open up the Sterling next week for a through spring cleaning. Then we will shut it down for the season and cover it with a wall AC unit cover. I honestly don't know if such a precaution is truly necessary, but reason that in winter, when it's operating, dampness isn't an issue as it dries itself, but when shut down it might be and protecting it from water spray is so easy to do. Nevertheless, regardless of brand, my husband the Great Depression reared farmer who can squeeze the last drop of life out of any machinery has always contended that with proper preventative maintenance, just about any gas furnace can be kept operational, literally forever. So when he performs the annual PM routine, it will also be wiped clean inside and out, the exterior checked for any nicks that could engender rust and if any are found will be attended to, then it will be waxed, sealed against damp and hopefully; will both operate perfectly and look good- for many, many winters to come.