Dear Luminita, I think I have some experience that relates directly to your inquiries. I have had a free standing BC Greenhouse ( about 50 ft from the house) for over a decade and have my share of problems. Since I live a few hundred miles south of you I share many of your climate concerns. First the good part. BC was excellent about building a custom greenhouse and assisting on all following problems. I would certainly consider them again. However, if I had known then: I would have selected a GH company that made it possible to use 4 or 5 layer polycarb covering. My BC green house is triple layer and there is no chance possible to replace the covering except with the same triple wall -which I have done once already. I would NEVER have a curved side greenhouse. After only 2 years of extremes of heat and cold the curved sides especially those closest to the harsh western sun cracked and allowed water and air to enter the inner layers with various bad consequences. The curved panels are under stress and temp extremes result in numerous small cracks. I would recommend ONLY straight side and roof panels. The basic BC greenhouse comes with 2 roof vents on opposite sides. Knowing better I had both roof vents installed on the leeward side of the roof ONLY away from prevailing strong spring winds. Even so within weeks the Western winds bent and broke both vents out of shape and they would no longer close. BC replaced these automatic vent openers with heavy duty openers at no charge. I had an existing concrete block foundation, but I should have built this up a foot or higher. I think this will keep the lowest level of the greenhouse house floor somewhat warmer than mine with sides lower right to near ground level. I would gain an extra foot of height too. This would allow more room for hanging plants, but require more volume to heat. Finally there is the heating. The cost of heating exceeds what I anticipated. Although I try to keep temps around 50 at night all winter, I have had nights where temps drop into the upper to mid 30s, but no freeze. You will have an even more difficult time keeping temps from freezing in MN. Here when outdoor temps reach 0 F I am in a very close zone of troubles. I’d be glad to talk to you about this in details if you’d like. I think it might be better if I could build a greenhouse attached to the main house, but think this could be a great way to have some closer controls of temps and make it much easier when connecting electrical and water to the greenhouse. This would hopefully reduce prices from the original costs to all those connected with heating and care. Good luck Jim W. _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>