eastpenna, Good question. Like most things I guess me review of the wire shelves would be "mixed". The good - wire shelving is stable (when properly supported), allows a decent amount of sunlight to pass through to lower shelves, works well for watering (overflow), and it does look very nice. The not so good - wire shelving can be a problem if you use lots of small cups (I often use the little, 3 to 7 oz, dixie type cups) for germination and seedlings. If they are not set in a near perfect position, they tend to tip over with the slightest of touch or when then they get hit with the watering stream. This problem, however, might also be true for the 2x2 system you are looking at as an alternative. The only way around it that I can see is to use solid board shelves, which will cut off light and be a problem with watering overflow. Or you could not use the small cups on these racks. In my case, I use the small cups and just learn to keep my swearing well muffled whenever they get tipped over. Maybe some other folks have come up with better options.

I would put 2x4 wood base for the whole greenhouse and them shim it level with blocks. Make the blocks of different thicknesses by the width of the 2x4 and attach them with screws or nails from the underside of the wood foundation. There will be gaps between the blocks fill some with insulation if you want. Maybe some gaps would be good for drainage on the low side. The hardware store will have all kinds of anchors show them a picture of the shimmed wood frame and tell ask them to help you with a plan. Make sure no hardware will be in the way of the bottom of your greenhouse. Then build your greenhouse on the frame and screw it to the wood. This post was edited by rustico_2009 on Thu, Mar 14, 13 at 12:10

Welcome, Sqftgarden. The previous post is correct - you'll find a wealth of information on the 6x8 HFGH if you run a search. Overall, I believe most people are very happy with them; in most places, they don't require the structural modifications the 10x12 does. I am in a similar zone, USDA 7, coastal New Jersey, have one and have been thrilled with it (though it is a little cramped ... but I think I'd have the same problem with a much larger one anyway, lol). The amount of info you'll find in a search can seem overwhelming, so, in brief, I believe I spent somewhere between $600& $800 all told; the following list may not be all-inclusinve, but probably close. Trailer rental for transport (we picked up at a local HF store), treated 2x10's & hardware for base, weatherstripping tape, caulk, gravel, paving blocks, benching & shelving materials, U-clamps for hanging things, circulating fan, electric heater, small propane heater for backup, wireless thermo-hygrometer, automatic roof vent, clear solar pool cover, 2 sheets 1" foam board for north wall & roof, hardware cloth and foil faced bubble-wrap type insulation for rodent and draft barriers around perimeter, GFCI outlet. I didn't buy a shade cloth, since ours is under a limbed-up tall oak, which provides dappled shade May-late September in all but the morning hours. Ours took about 6 hours to build (we had prepared the site the day before, and electric had already been run to the garden shed, so it was a very short run from there to the greenhouse.) I can provide you with more specifics, but first run a search and take a look at what others have already posted. Lots of good ideas out there, and "Conifers" posted a wonderful set of photos and notes documenting his assembly. A lot will depend on what your site is like (i.e., any special conditions like high winds, sloping ground, etc.) and how you plan to use the greenhouse. Be careful, though, as these things can be habit-forming. I am completely hooked ... I'd give up my second bathroom before I'd give up my greenhouse! Diane

I think your concern should be focused on how hot it will get in the daytime. The small GH is really had to cool. I have a 10X12 and had a lot of water in it but it was taking up to much space. I needed the space for my plants so I removed most of the water and the difference to the heating bill was not noticeable so next year I will use none or very little water. If you put 100 gallons of water in the small GH then you will have the thing full of jugs. Like my wife said we built the GH to grow plants not store water in it. I know the thinking by most on this forum is fill it with water but if their is a savings it is so small that it is not worth it I would rather use the space for growing plants. Buy the bigger one and sit it where you will have room to put another one end to end with the first one because even the 10X12 is too small