hpedley, we built our 10x12 Harbor Freight greenhouse over six years ago, and it's filled with plants 365 days a year. They are a very inexpensive way to try having a greenhouse, compared to the costs of other kits on the market. However, there are some inherent weaknesses in the kit that require some inexpensive modifications for strength, and for securing the polycarbonate panels more securely. Many Gardenweb members had posted their modification ideas here, before we built ours. I gathered many of those good ideas and documented them in a blog, as we built ours. It has a lot of information about the strengths and weaknesses of the kit, and reading here may help you determine if the Harbor Freight greenhouse is right for you. Building our Harbor Freight Greenhouse There are other good tutorials on the web as well, including this one for the 6x8 Harbor Freight greenhouse: Building and Improving the Harbor Freight Greenhouse In my opinion they are a great value for your money, but only if you're willing to spend a bit of extra time and labor doing some modifications so they will withstand wind. The HF manuals are better than they used to be, but still frustrating to use, so it's a good idea to seek out additional information on the internet as you build. People who go to Harbor Freight, buy the kit, and build it only as per the manual (with no modifications) are usually the ones who have unhappy experiences. The kits require some tweaking.

I can't tell you what to do, Hoover67, but I can tell you my experience with a HF 10x12. We first put it up in 2007. Since then we've had a thunderstorm blow out panels that were secured right well and hail put holes in some panels that time and sunlight made brittle in the Deep Sunny South. We replaced all panels after 4 years. We started out with extra bracing and reinforcement. This winter another storm caved in the door header and blew out 4 panels again. We've repaired all that and added a fan in the opposite end, just in time for another series of thunderstorms today. We are under a tornado watch. We anticipate problems and keep coming up with solutions. The initial cost of the GH is not the only expense. You'll need something for a base, at least a pathway of pavers on the floor, electricity and water source, heat for the winter. In the years before the GH, I put an old kitchen cart in the tool shed and trundled flats of seedlings in and out on sunny days. I grew cuttings in an east-facing laundry room with two windows. Grow lights might be your best solution unless you just enjoy an on-going project as we do. Here is a link that might be useful: NJ's Greenhouse blog, Dotty Plants

dbw7, thanks for the correction about the gable ends! Not sure if this is what you're seeing, but all of the panels have traditionally been shipped with a clear plastic film on both sides that needs to be removed before the panels are installed. (The part number labels are stuck onto this plastic film.) UV protection is a clear coating that would not be removable...no way to tell if that is present without laboratory testing of some sort, I believe. We just have to rely on the word of the manufacturer we're purchasing the kit from...which is where some of the controversy comes in regarding Harbor Freight. If the white material is designed to be in place for shading, and the white material is already starting to peel away from the panel, that would be a bit worrisome to me...but maybe you could secure it by simply adding some aluminum tape to the edge of the panel.

Yes, I have read of people bolting them down. How do you do that with out harming the panels? It doesn’t harm the soft polycarbonate panels to put a screw through them. You could drill a small pilot hole and insert a screw, or use the self-drilling screws we used. We only used one screw per panel, roughly in the center of the panel. Man the panels are like cardboard and will be amazed if they hold heat... Normal winter temps are in the 30's sometimes cooler. Twinwall polycarbonate is much more efficient at holding in heat than a single layer of glass or fiberglass. Our lowest winter temps are usually in the low teens, in a normal year. You can check out the different heat loss values for different covering materials, at the calculator I link to below. I plan to run a heater and add a 60 gal water barrel. Most people find that trying to use stored water to retain heat through a cold night doesn’t work very well, especially in a small greenhouse where space is already at a minimum. You might search the archives for more opinions on this topic. I use two 1500 watt heaters in my 10 x 12 greenhouse, zone 8. The link below is to a greenhouse heat calculator you can play with, to figure out the amount of heat you’ll need, based on greenhouse covering, size, minimum outdoor temperatures, etc. When you use this calculator, remember the HF twinwall polycarbonate is 4mm thick. greenhouse heat calculator Should I use washers too? Sure, wouldn’t hurt. Washers will help prevent the bolt heads from biting down into the surface of the wood, as you tighten them down. If you haven't done anything like drilling into concrete before, you might want to find a neighbor or buddy who can give you a hand with it. Weather stripping is a good idea,but even with my smaller model that can be pricey. Where as the screws and silicone or caulk might be cheaper? I bought my weatherstripping on eBay from a surplus seller, for a much lower price than our local box stores. It was too wide; I just cut it lengthwise with scissors. So from your blog I can expect there to be gaps for water leaking in and heat escaping. Not quite sure what you mean; I had a few gaps at the tops of the corner posts, as I explain in the blog, and fixed those with clear caulk. I don't have water leaking in. I also post in the blog that I haven’t regretted the time or money for the weatherstripping, since I think it helps prevent heat loss. I can’t measure how much of a difference it makes, truthfully, since I haven’t built a HF greenhouse without using weatherstripping. Not sure exactly on the aluminum tape at the ends? You said to tape it to seal it then you put holes in it for air exchange which I understand. But if you put holes for air exchange then what purpose is the tape doing? I’ve currently switched to using clear duct tape (Lowes) on my panel ends; it seems to last longer in our high heat. The aluminum tape worked fine, but peeled off after about two years of our brutal sun. Here’s a thread that explains more about this: thread discussing sealing polycarbonate panel ends The above thread also has some information about how to order extra Harbor Freight panel clips, if you decide to.