svalli and kicksnj, I apologize to both of you for missing your posts. I haven't been able to check here for a while. My husband and I made our living by forging iron and fabricating items out of mild steel, so I'm pretty familiar with my old friend rust (we have a saying, rust never sleeps.) Steel is always trying to return to its natural oxidized state, but with modern finishes and a little maintenance, we can usually keep the enemy at bay (in most climates, anyway!) Sorry to hear that rust is trying to interrupt your greenhouse projects. Without seeing photos of the rusted bases, I'd tend to imagine the blistered paint and underlying rust are more of an annoying (and admittedly worrisome-looking) cosmetic issue than a true structural risk. My approach would be what kicksnj suggested; remove any loose or blistering paint with a steel bristle brush, rough sand paper, or rough abrasive pad. Then prime any roughed-up areas with a good metal spray primer (Rustoleum is good) and follow with another coat or two of a good spray paint made for exterior use (again, Rustoleum is a decent brand.) I'd sure rather pursue this approach than to abandon using the base, since as svalli mentioned, the clips that hold the vertical aluminum beams in place are anchored by the formed lip on the steel base, and then you have another set of challenges. I wonder if Harbor Freight has modified the finish on these steel bases, as our 4-year old base still doesn't show any signs of rust (but, we do live in a dry climate.) Svalli, since you've already constructed the two-by-four replacement base, I'm trying to visualize your challenge. I'm sure you've found that the hold-down connectors (part 47) do two things at the same time; they not only secure the aluminum floor plates (parts 1 - 6) to the steel base; they also attach the vertical aluminum wall studs, at the same time. So, even after you screw the aluminum floor plates to the top of your two-by-fours, you'll have to figure out how to attach the vertical wall studs to the aluminum floor plates, with no hold-down connectors to help. You may already have a solution for that, but I'm just making sure. The polycarbonate panels do touch the vertical lip of the aluminum floor plate; the panel clips (part 53) press the panels tightly against the aluminum frame, from the outside of the greenhouse, for air-tightness. It would probably be best if the screw heads did not fall in the area closest to the vertical lip, since it might affect the panel fit. The actual measurement from the outside of the poly panel to the outside of the aluminum floor plate can vary, depending on whether or not you use weather stripping between the polycarbonate panel and the aluminum frame. (I did.) What matters most is that you realize the poly panel needs to be able to fit tightly to the frame (or to the weatherstripping smooshed against the frame) if you want to avoid air leaks. If I'm misunderstanding, please feel free to post back! Again, apologies for my slow reply. I hope some of this helps. Hang in there, the challenge has been well worth the end results for me.

Marcie, your question came at a very fortuetous time.. I just today finished installing screens on my Clearspan Prostar 12x24 Ghouse. I too was baffled on how to do so until I visited my local LOWE"S store. They have this porch creening "system" that I found fits the bill just fine. it is a plastic "profile" about inch and a half wide with two channels to hold the screening and the spline. The instructions in the link below shows an installer using wood screws to attattch to a porch BUT I had very good luck using selftapping sheet metal screws (#10-3/4") to attach the system to the aluminum frame of my intake vent( which is aluminum ) the system also includes cap strips of assorted colors to cover the screws. System also works best with the .175 inch screen spline. Here is a link that might be useful: porch screening how to at Lowes

Good morning Jeymac, Iâve been happy with the solution of putting wood framing along the inside of the base channel. I do think it strengthens it somewhat (prevents the c-shaped channel from flexing as easily.) Also after years of living with the greenhouse, I think the bottom of that channel would have been a great catch place for bits of gravel, plant leaves, dust, bugs, and other greenhouse debris. Having the wood there makes it look cleaner, and it really does stay a bit cleaner too. Iâm sure my wood does not look as pristine as it did, years ago, after I slobbered water all over the benches, week in and week out. But I never notice it, back there under the benches. Neither my husband or I can recall what Gardenerwantabeâs base braces looked like, although I bet at the time we looked at those photos and considered that. We must have decided they were not critical, along with the wood we used, as we are both drawing a blank on what his braces were. I guess we are getting old? I donât really have any knowledge of anyone else using braces on their base to strengthen it, so I donât think itâs a deal breaker, but I do understand the wisdom of thinking through any options for adding strength as you go. I donât have a great source of larger photos for the details of joining two greenhouses together, although I try to watch for that on the web, since the question of joining two greenhouses comes up fairly often. There have been a few folks who have mentioned doing this on GardenWeb, but I donât think any have posted step by step close up shots. Funnylady has been super nice when we have emailed, and I hope she can give you more specific answers. If you folks do join two together, you might consider doing a thread on Gardenweb with the nitty gritty details of how you joined them....Iâll bet others would thank you, down the road! So many times, I find that everybody who builds one of these seems to find their own way for resolving some of these questions. I know we did, too; we researched everything we could ahead of time, but often ended up finding our own solution, based what seemed practical at that moment...what we could find in the garage to use...and/or what we could find in the aisles of Lowes. In other words, on most any of these modifications, youâll find there is more than one way to skin the cat...and the way you find may well be a better solution than what other folks have done. I didnât make any notes about the length of the bolts we used with the EMT, but since the EMT is ¾â, weâre guessing maybe 1 ¼â bolts. Just enough to slip through the drilled EMT and add a washer and nut. Best of luck with your build!

Wow James, I've seen a lot of reports from people missing one or two parts, but never missing the entire aluminum frame! And bolts! That's a first. Really a bad deal since you have to drive so far to fix the problem. You're probably way ahead of me, but once you get the missing box, I always recommend checking all the frame parts against the parts list in the back of the manual. The parts should have numbered stickers so you can make sure they're all there. It's rare, but sometimes people get halfway through the build and find the kit is missing a critical piece of framing. The kicker is, HF usually only keeps parts like replacement panels and clips on hand for fairly quick shipping; other missing parts can take weeks (or months) to get shipped to you. One person I know waited six months for part of the door frame. In that case it's better to throw yourself at the mercy of the HF store manager, sometimes they'll crack open a kit and provide the part you need. (Sometimes not.) But hopefully you're overdue for better luck, and your box of frame parts will be complete (as I think most are.) Yeah, we live in the desert (warm/dry) but still didn't want to bury our base in the ground, either. I think most folks attach the base to a wooden or concrete foundation. With your climate and the frost concerns, I can sure see your point. The HF greenhouse really isn't built to withstand a lot of snow load; the centers of the roof studs are the weak points. If that's a concern for you, I can point you toward some threads with ideas for extra interior snow bracing, just let me know.