In the interest of helping Darrin get his base strengthened, I'm linking to a post that has lots of information on that subject. Reinforcements to the base can be heavy strap metal and cut and flanged angle iron (which we used, 8 each) or flattened conduit (others used) as long as they work. The steel anchor posts being 4 feet or six feet into the ground and at the corners or on the sides are of little difference. Do what works, use what you have. Gardenerwantabe made this excellent point: "All the side wall studs attach to the base with part #47 a J hook and it hooks under a flange on a lip of the base. The base it very thin sheet metal but when you bend a lip on it then anchor at the end of the lip a very small amount of pressure will cause the lip to flex. The only thing that keeps the top of the wall studs from moving is they bolt to the top rail and the top rail is bolted to the corner posts. The corner post is to hold the whole thing together but the only thing that holds the corner post is the same flimsy J hook under the lip like the wall studs. I reinforced the corner posts made them very strong this gives the rest of the structure something to anchor too. When the wind pushes on a wall the inward push will try to release the J hook the only thing that keeps it from going inward is the top rail bolted to the corner post and the top rails at the end will push against the opposite side." We used a different approach by anchoring each upright at top and bottom with extra bolts and perfed metal straps. There are also straps holding the rafters in the same manner. Little cost, a couple rolls strap and a box of extra bolts, and nuts. Again, do what works for you. I would suggest to go ahead and order extra spring clips from Harbor Freight so they'll get shipped soon. Nell Here is a link that might be useful: More Input

Gardiner is the HFGH construction expert here, but I would like to suggest an alternative to a sheet of plastic between your aluminum base and copper treated timbers. Check your local big box home center for the rolls of 3- 1/2" wide vinyl sold for sealing sills under standard 2 x 4 framed exterior walls and unlike plastic sheeting, made to last as long as the structure. Every time we visit our local Menard's and/or Home Depot or Lowe's, I'm always amazed at the latest in materials and just as regretful that they weren't around when our old house was constructed, so do wander the construction materials areas, and you too may find a product that may not be advertised exactly for your intended use, but one that could prove ideal anyway. Another possibility is vinyl siding. It comes in 10 ft. lengths, is very cheap per piece, but again, made to withstand the elements and just a few pieces of the 5" width laps, would cut to fit and cover the tops of the timbers. Of course, the ultimate and perhaps, in the end, best of all timbers for a GH base, might be the resin timbers that will never rot, are always perfectly straight, will never bow or warp, and don't require any barrier at all.

Metal yards, and some sheet metal shops do railings. They can either weld the entire thing up, or more commonly use a combination of 'standard' pieces with some custom pieces to make the required railing. Just as an example, the upper and lower rails come in longer lengths that are cut to size, the verticals the same way, and a quick weld top and bottom attaches each vertical. If you need a stair railing you jig up the pieces at the angle you want before welding them together.

With apologies, I'll post a half-answer, because I'm helping a relative with a move and I don't have access to my manuals (and some of my brain cells, lol.) Over the years I can recall another HFGH owner years ago, contacting me through my blog, and they didn't want to use the steel base for the 10x12 either. Their concern was a very wet environment; they felt the steel might not hold up (although I don't know of a steel base ever failing; they're pretty heavy.) I know they were successful with their build, but I don't know the specific re-engineering steps that eliminating the base may have caused. So it's possible to eliminate the base, but if there are resulting tweaks I can't outline them for you. You might specifically check to see if the part 47 hold-down connectors (that secure the diagonal braces to the base) attach to a lip on the base itself, or to a lip on the top plates. (It's been too many years since my build, and I can't recall...and don't have easy access right now.) I just have a question in my mind about that possible complication. In my warm climate I didn't mind the extra inches of height that are contributed by the base, even though we mounted our steel base on top of a (taller) wooden foundation as well. My biggest problem is cooling, and warm air rises, so a slightly taller greenhouse was a slight advantage for me. It did require me to build a few paver steps up to the doorway on the outside of my greenhouse, and there's a very slight step down to my paver floor inside. Apologies for the half-answer! Maybe someone who has built one more currently could do a little brainstorming with you. I do know these kits lend themselves well to re-inventing, if you're willing to figure out the possible solutions. Over the years I've been very impressed by changes that are possible with a little creativity.