I heard of (and saw) more hoophouse casualties this winter in Michigan than I ever have. In every case the culprit in the collapse was either heavy snow or unusually high winds. Don't underestimate the potential effect of snow load on your house, and try to remove snow (especially when it's wet and heavy, or particularly voluminous) from your houses if you can. If you can protect it from high winds, by placing it on the other side of a treeline or hill from the direction of prevailing winds without losing significant sunlight, this might be worth considering. Also, see if you can get some kind of guarantee from the manufacturer regarding durability, or at least written documentation of their claims regarding the capacity of the house to withstand wind and snow load. And document your build with pictures and notes. The last thing you want is to spend money on a hoophouse (high tunnel), then have it collapse on you, then have the manufacturer tell you they don't guarantee their products or that it's your fault for assembling it incorrectly. There are also certain packages that offer stouter materials and more robust designs. The structural design of end walls may also be important. The house in the picture below was a rounded design with simple aluminum end walls (as you can see from the picture). Rounded houses may* be less capable of standing up to heavy snow or allowing it to slide off than peaked roof houses (though I know of some of these that collapsed this winter as well). Finally, try to get assistance with your first build from someone with experience. This can both save you time and help assure you that you are assembling your house correctly. *I'm not an engineer, but this seems logical to me.