Update, December, 2008:
"UV coated polycarbonate panels, nearly indestructible"
...several Harbor Freight greenhouse owners in warm climates are now reporting deterioration of the polycarbonate panels. After contacting Harbor Freight with questions about this new issue, and receiving some email replies from them, my personal opinion is there's a good chance the polycarbonate panels supplied with this kit do not have the critical UV coating as advertised on the Harbor Freight website. Or, if there is UV protection applied to the panels, it's inadequate to protect the polycarbonate from damage when exposed to strong sun/high temperatures.
Here's part of an email I received from Harbor Freight customer support, May 5, 2008:
"Our panels are constructed to resist the higher ambient temperatures but
that may differ depending on what state the customers are in. Places like Arizona, Las Vegas, and Texas may cause them to deteriorate faster. Unfortunately our warranty on the parts for this item is only 90 days and we take case by case in determining how we replace the panels for each customer. We know that the panels last longer than that but from a company stand point that is the warranty."
I started seeing some yellowing of my greenhouse panels as early as May 2008 (after about 9 months of exposure to our strong desert sun.) I don't know how long they'll last or how soon I'll need to replace them, but I think folks who live in very sunny climates should take this into consideration when buying a Harbor Freight greenhouse. I'd recommend reading this thread at GardenWeb, which documents this problem first coming to light: http://forums2.gardenweb.com/forums/load/strucs/msg0410080322640.html?39
mudhouse
December 2008 ________________________________________________________________
Okay, back to business, and the start of my blog!
Click here to see the greenhouse we bought from Harbor Freight.
It has an aluminum frame, a sliding double door, four roof vents, and 2 ply 4mm polycarbonate panels. It’s 10’ wide, 12’ deep, and stands about 10’3” tall at the peak (taller if you put it on a wooden foundation.) It comes in one box that weighs about 200 pounds. If you're wondering if it will fit in your vehicle, the box is 8 ft long, 25 in wide and 13 inches deep.
Harbor Freight currently sells it for $799, but they put it on sale occasionally. The price makes it attractive; at this time, I don't know of another 120 square foot greenhouse with twinwall polycarbonate glazing in this price range. If you sign up for Harbor Freight's mailing list, they'll mail you flyers, and occasionally these have coupons for up to 15% off. Sometimes you can buy Harbor Freight coupons on eBay. My local HF store kindly honored the internet sale price (even though it wasn't on sale in the store) and they applied a discount coupon on top of that. Nice!
After putting ours up in August of 2007, I think this greenhouse is a fit for people who aren't ready to spend thousands of dollars on a greenhouse kit, and who also have the time, skills, and patience to make the necessary modifications to it.
If you do much reading on the internet, you'll find the HF 10x12 has a reputation among some for being lightweight and unstable in winds, if built only as the manual specifies. (In a very sheltered location it might not require all the modifications we made, but personally I wouldn't take that risk.) When the unmodified structures are exposed to high winds, some people have lost their greenhouses entirely, and others had damage. People who’ve taken the time to share their stories about these heartbreaking failures have helped others pinpoint weaknesses in the kit.
Since its introduction (early 2006, I believe) creative folks have been working on ways to modify the Harbor Freight 10 x 12 kit and defeat the weaknesses. The people who post in the greenhouse forum on Garden Web have been especially helpful, blazing a trail through the murky confusion of the Harbor Freight greenhouse manual, and freely sharing ideas for critical changes to the kit. They have been absolute lifesavers for us, and I highly recommend some reading there. To find these posts, just go to Garden Web and enter "HFGH 10x12" in the search engine box.
Our experience has been that the Harbor Freight 10x12 can be successfully modified to correct the kit weaknesses, with some patience, a little extra work, and a few extra materials. We've never had a greenhouse before, but I'll show you what we did, and you can probably do even better.
Here are some commonly discussed issues with the kit:
Aggravating Assembly Instructions: We think the manufacturing quality of the Harbor Freight 10x12 is actually quite good. We've been pleasantly surprised by the quality of most of the parts, which seem to be well made. There were no misdrilled or ill-fitting parts in our kit. However, the instructions are even worse that we thought (and that's bad!) No photos, tiny drawings, missing info and errors make assembly harder than it needs to be. This is a shame!
Sometimes it’s easier to just look at the parts and figure out how they logically go together, or look at photos of other HF 10x12 greenhouses online. I've included many photos for this reason. You still need the manual, but hopefully our photos will help.
Here’s a link to a PDF file of the manual on the Harbor Freight website. As I write this, the manual in this link is the same as the one in my kit (dated 05/06 on the manual cover.)
Missing Parts: It's a very good idea to check your kit early against the parts list. Some people report missing parts, and this can be a major setback. People report that Harbor Freight says they'll ship the missing part in 6-8 weeks, but I know several people who have waited over a year. This seems to be the biggest customer service problem with Harbor Freight (incredibly slow shipping of parts.) If you find a part missing, and you bought your kit at a local store, you might consider taking the whole kit back and requesting a new one. Or, see if you can convince your local store to pull the missing part from another kit (some people have been able to do that.) Our kit was complete.
Harbor Freight says they're aware of this problem, but they don't foresee the ability to stock all the parts for quick shipping anytime in the near future. (Moral: check your kit.) I think the need for aftermarket replacement parts will increase as more of these units are sold, so I'm hoping they'll focus on this as an area of opportunity for future sales. (Come on, guys!)
Order Extra Panel Glazing Clips Early. They do keep glazing clips in stock, so you can usually receive them in a reasonable time frame. To find out why you need them, you can skip ahead to the "Adding the Panels" section.
Questionable Bolt Quality: The bolts supplied with the kit look like aluminum, but they do stick to magnets, and seem to actually be plated mild steel. They're not great quality, and sometimes the nuts wouldn't thread easily on the bolts without force. On the plus side, they have square heads that bind nicely in the stud tracks, which helps when you're tightening them. Also, the heads are quite flat, so they lay low under the polycarbonate panels on the outside of the greenhouse.
Some people use the kit bolts; others toss them and go buy stainless steel (or other) bolts and nuts instead. We used the kit bolts and bought a few extras as we needed them.
Wrong Bolt Quantity: A really annoying error in this manual lists wrong quantities and lengths of bolts to insert at key points. This means you have to take things apart later to add more bolts. The manual dated 05/06 contains these errors (I'll point it out when we get there.) Earlier kits did not even include enough long bolts to complete the construction, but recent kits seem to be shipping with closer to the right number of bolts. Still, you may well need to buy at least a few that aren't supplied.
If you buy bolts, the heads need to fit in the track of the posts. Some bolt heads are too large. We took a wall stud to the store with us. One kind person posted this specific info for Fastenal bolts that fit:
Bolts: hex head 6mm-1.0x35mm zinc, Fastenal part#1138568, $17.95 for 100
Nuts: 6mm Fastenal Part #1140305 $3.40 for 100
You can also add bolts after assembly by using T bolts (from Fastenal or Charley’s Greenhouse Supply.) Or, some people just take a grinder to a regular bolt head to make it fit. In a pinch, we also used 3/16" carriage bolts, clipping off part of the head with a bolt cutter.
Changes To The Kit: To their credit, Harbor Freight has revised the manual several times to correct some errors (mine is dated 05/06.) Also, some parts have been changed or improved from one kit to the next, so they may not exactly match the manual. This makes it harder to be helpful in this blog, since your kit might be slightly different from ours. Some of the errors mentioned here will probably be corrected in future manuals and kits.
The photo to the right shows the tool we found the most useful for tightening the bolts...a 10mm nutdriver.
And here's a photo of the little wrench that Harbor Freight includes with the kit. Other than making you smile, it's not helpful. (I'm pretty sure the Chinese manufacturer only includes these to prove they have a sense of humor.) Actually there were two in our kit, but that did not convince my husband and I to use them.
Click here to go to Part Two: The Foundation, the first modification we made to the kit.
16 comments:
Thank you so much for doing all this documentation, it certainly made my construction go along much better and I did it all myself. The only thing I would add is just the advice, and you touched on this, to attach the angled supports to the corners right away. since I built this on my own I had no one to help hold things but attaching the cross supports, loosely, everything had enough support to build upon. Even doing the roof, and I can't imagine anyone doing as the manual says building it on the ground and then putting it up. I was able, with help using a pole to hold up the other end of the roof peak spanner as I attached one side, to attach the roof solo.
But great job on this blog!
how long did it take you to completely assemble your greenhouse?
Hello rcarrcrew,
A good but hard question! We made no attempt to complete the construction quickly, and worked on it as we pleased. Stopping to document and photograph the tricky parts (for this blog) took a lot of time. Also, we halted construction at several points to do things that others do later; for example, we did the rough plumbing and wiring, and built the benches and greenhouse floor before we finally put in the panels. (It made sense to do that because our climate here is so warm.) It was probably about three months total from the time we started to having the exhaust fan, thermostats, shadecloth, and sink in place, but we weren’t trying to hurry at all.
A lot depends on how complicated your foundation is. If you live in a very cold climate, you may need a more sophisticated foundation than ours. Some very conscientious folks spend weeks preparing and building the foundation alone.
It took us about 1 ½ days to put in all the panels, but that was because I insisted on adding weatherstripping on all four sides of each panel opening as we went, and we screwed each panel down as we went. (I don’t regret adding the weatherstripping.)
Now that we know exactly how the thing goes together, my husband and I think we could probably erect another Harbor Freight 10x12 in three long days...IF the foundation was already built, with no plumbing, electrical, etc. However, that’s only because we’ve already built one.
In case you’re asking because you’re considering hiring help, I’ll share this...an online friend hired a handyman to erect the greenhouse for her, hoping the basic construction could be accomplished in a few days. Long story short, it didn’t work that way. A series of handymen started the job and never returned (once they saw how confusing it was, when looking at the manual “cold.”) The basic greenhouse shell was finally completed with the help of a kind and patient neighbor, some time later.
Any greenhouse is an ongoing project, since you often don’t know what you need to add, until you see how it’s working (or not working.) It’s so much more than just the initial walls, and the date to declare it really "finished" is somewhat of a moving target! I hope this very rambly answer is a little helpful.
mudhouse
Hello rcarrcrew,
I'll throw in my two bits as I concentrated on just the building without getting too much into the extra's. I posted a few pictures from my effort here
http://web.mac.com/tandgleeds/wormbucket/Greehouse.html
The time frame building my greenhouse was one weekend to make the base. I did my base as a wood frame, the ground was uneven so I had a bit of digging to do and then I attached a tarp on top of it loose enough to sag to the ground and I loaded a 1/2 ton of pea gravel on top of the tarp. It took almost 2 weekends to build the frame which I was able to do completely by myself though I had to get creative to do the roof. The panels I did sporadically as I prepared them with tape on the ends. I also drilled holes to attache them to the frame and did some of the other structural enhancements. All in all it took about a month of spare time while working 50-60 hour weeks.
Now that it's winter in Chicago, I'm storing all my outdoor potted plants which normally were in the garage.
My only word of caution is to think long on where you are building, the 10x12 is very big and will block your view even from 2nd story window.
Solong4now
Howdy solong4now! Thanks so much for adding your comments here, and for the link to your good pictures. I appreciate all of your input, including how long it took you to build your greenhouse. I suspect many folks wonder about that, but I struggle with that question since we were as slow as molasses in building ours.
Lovely gardens around your greenhouse...mine looks barren by comparison.
mudhouse
wow, this blog is an incredible resource! I've been tempted by the comparatively low price of HF kits. All I can say is you guys are absolutely awesome and show the patience and problem solving skills of saints. It seems it may actually be easier and cheaper to custom design and build one's own greenhouse....
Hello Peter, and thanks! I've seen some posts about folks locating salvaged components (doors, windows,etc) and building their own greenhouse for a low price, so I know it can be done. This HFGH was a good introduction for us, though, since we frankly would not have known how to design a greenhouse on our own (never having owned a GH of any kind previously.)
Not really sure if a home-built would be easier than this kit...probably some types, like a hoop house, would be. But generally I think most greenhouses end up being a good chunk of work regardless. Good thing gardeners are generally stubborn optimists!
We agree we'd be more comfortable trying to scratch build a greenhouse now that we've owned this one for a few years. But before this kit...I'm not sure I would have had the courage to leap into unknown waters!
Sheri
Please check Multiwall Polycarbonate panels made by Polygal. they come with 10 years warranty.
In the USA www.polygal.com
In canada www.greenwallsolutions.com
Is there anyway of finding out if the panels are from www.polygal.com? There was no documentation about the panels in my kit, not even if the UV coating was on one side or both and HF had no clue. I live in Illinois so hopefully will not have the degradation issue but if I do it would be nice to have a warranty backup.
Hello 3Leeds,
Your lack of answers from HF fits the experience of others, and fuels my suspicion that no UV protective coating has been applied to either side of the HF twinwall polycarbonate panels.
The Harbor Freight greenhouse kits are manufactured and packed in China, and it's my belief the poly panels are also manufactured in China. I hold out little hope they're manufactured anywhere else.
When I contacted Harbor Freight back in May of 2008 about the panel deterioration problem, this was part of their reply:
"Unfortunately our warranty on the parts for this item is only 90 days
and we take case by case in determining how we replace the panels for each customer. We know that the panels last longer than that but from a company stand point that is the warranty."
From my looking around on the net, I find many reputable manufacturers of twinwall polycarbonate offer respectable warranties, but Harbor Freight's poly panels do not. I'll definately take warranties into consideration, as Greenwall suggests, when I need to replace my panels.
Sheri
When I was looking into designing and building my own greenhouse that was going to be smaller (8x8x8 aprox) the cost of UV polycarbonate sheets added up to almost $500. I don't hold much hope for the quality of my HF kit but I was able to get it for $570. I am happy with the frame and it wasn't too bad to put together. I think it will last quite a few years and if I have to replace the panels I will do just the top with high quality sheets and something lesser on the sides if and when they need it.
Exactly! That's the way I look at it too. Even with the eventual panel replacements in my very sunny climate, my HFGH has still been a very good value for me. The foundation, frame, plumbing, electrical and benches are all secure, and I'll decide how many and which panels to replace as time goes by. Here's hoping you'll be able to have many more years with your panels before dealing with replacements..in your somewhat kinder climate!
This has been a great help. Like you I have the base sitting on 4X6 pressure treated lumber. I tried to bolt down the base before assembly of the sides but found I would warp the base and take it out of square. I see in your pictures that you have added a wood strip to the inside of the base. Can you tell me more about what you did with the base? Thanks John Port Orchard, WA.
Hello John, I'm out of town right now, but will reply on Tuesday. Also, you're welcome to email me at mudhouse@q.com, and we'll be happy to do our best to help.
Sheri
Back again, and I’m sorry for the delay. We’re not sure why attaching the metal base to your wooden foundation would warp the metal base out of square, unless your wooden foundation is not quite level, and/or out of square. We took a long time to make sure the 4x6 foundation was level and square before adding the metal base; checking, readjusting the wood, and adding or removing soil as needed to make sure it was flat and level. Once it was level and square, we anchored it with the rebar pieces as shown in the photos, and then checked for level and square again.
After we had the wooden 4x6 foundation square and level and anchored, we also added some short diagonal braces inside each corner, made from 4x4’s, just to make the wooden foundation less likely to move as the wood dried over time (the lumber we purchased was pretty wet.) Those also show in the photos in Part Two, The Foundation.
Also, we used some blue polyethylene sill insulation in between the pressure treated lumber and the metal base (shown in Part Two, The Foundation) and that very slight cushioning may have helped compensate a bit for any slight natural waviness of the wooden surface. After taking these steps, we didn’t have any problems with the metal base being pulled out of square as we attached it to the wooden foundation.
The 1” thick cedar boards you asked about were added to the interior of the base much later (Part Five, Modifying the Frame for Strength) after the greenhouse framework was completed. They didn’t have anything to do with getting the base square or level. Several GardenWeb forum members suggested adding boards or metal plates to the upper and lower lip of the C-shaped metal base to prevent it from flexing as wind pushed on the greenhouse walls. We also liked the idea of filling the void with some insulation before adding the boards…and we thought it looked nice as well. Basically those boards just covered up the open void in the metal base, preventing dirt and water from accumulating in there, and add a bit of rigidity to the base.
Let me know if this doesn't answer your question, and we’ll be happy to try to help!
Sheri
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