The Harbor Freight "UV coated" twinwall polycarbonate 4mm panels are supposed to be just like the 4mm UV coated panels that other greenhouse companies sell, so this newly surfacing problem with some HFGH poly panels is confusing. No one really knows whatÂs causing it or how widespread the problem is; it seems to be happening more in hot climates or intense sun conditions. I have the HFGH 10x12.

The Harbor Freight website specifies that the panels are "UV coated." Since my panels (in intense sun) are only 8 months old and already starting to yellow, I believe that the advertised UV coating is either missing from my panels, or is certainly inadequate. Some twinwall polycarbonate panels come with a 10 year warranty against yellowing, so I believe something is amiss. Trouble is, the coating is invisible so you really have to rely on the word of the manufacturer.

IÂm thinking this problem is probably unique to Harbor Freight (manufactured in China.) I have not been able to turn up similar complaints about other greenhouse UV coated twinwall polycarbonate panels on the internet. I think itÂs unlikely youÂd have the same problem with twinwall polycarbonate panels that other companies sell. IÂd be sure the advertising states that there is a protective UV coating on the panels, and IÂd personally look for some kind of warranty (as an indication that the vendor believes the product will last for a reasonable period.)

Apparently polycarbonate panels that are UV coated will arrive with one side clearly labeled as to where the coating is, so youÂll know to face the UV coated side out. The Harbor Freight panels are shipped with no such indication on either side, which adds to my suspicions. ;-)

ThatÂs what IÂve been able to piece together so farÂhopefully others here will chime in!

I have my 6x8 HFGH for 2 years and the panels still look new. I do cover it from late April to mid Oct. This year It's covered with an old large white bed sheet.

Keep touching that wood! Yes, it would be super to have access to more HFGH owners, to look for patterns or common elements. Selfishly, I'd especially love to hear from folks in hot/sunny climates who'd enjoyed their HFGH for 3-4-5 years with no signs of panel deterioration...

I've had my 6x8 HFGH for just over two years. Eary this Spring I noticed that the panels were deteriorating with small holes and cracks. If I order another one from Harbor Freight, I'll remove the panels from April to October to help preserve the panels. James

I'm in Ocala, FL. Have had my 6X8 HFGH for 4 years. See no problem yet but I keep shade cloth on it year round because of the heat down here. I also have 2 of the 10X12 HFGH. One is 2 years old with no problems and the other isn't a year old yet. But see no problem with them at this time. Also shade cloth on at all time because of the heat and the fact that I grow orchids in them. The 2 10X12's are hooked together to make a 10X24 GH. Love it that way. I use 70% shade cloth. The large one has aluminet on it and I don't like that as much as I do the shade cloth from Arrons Creek Farms which is black. I have 60 orchid hanging from the roof so I can walk under them and grow other things on my benches and shelves. I also have a Julian GH that has 6m polycarb that is 5yrs old no problem with that either. YES I'M A GREENHOUSE NUT I'm retired and loving every minute of it.

Could someone tell me where to search for the shade cloth that fits the 10x12 HFGH? I tried searching Arrons Creek Farms and it came back "could not find". I would like to get one for my greenhouse that I put up in April 08. I surely dont want to endure the cracking panels after all the headaches we had to go through to get this project completed!!! Thanks Jackie

Go to www.littlegreenhouse.con This will take you to ACF

Based on my searching, and buying, www.amleo.com has the best prices for cut-to-size greenhouse shade cloth. You will need to accurately measure the sizes you need, ask for grommeting, and the installation is fairly easy with "ball bungees". Depending on your summer temps., I would select 50-70% shade factor, assuming you are trying to reduce summer inside greenhouse temps. and are planning to place the shade cloth outside the greenhouse. Putting shade cloth/aluminet inside does not reduce greenhouse temperatures.

I am curious as to the brand name of polycarb used by Harbor Freight. I used a commercially available brand when I rebuilt my greenhouse and it is only now beginning to yellow, after 10 years. I added on and used another brand of commercially available plycarb and it is yellowing ater 6 years. I think may be the brand used.

Not a chance that the brand will be revealed.

I have asked HF several times which side has the UV protection. Still waiting for an answer.

I don't know how much it adds to the manufacturing cost to make a properly UV treated panel, wherever it is made.

There was a TV station who did a comprehensive testing of sunglasses. They found that all the cheap cheap drugstore sunglasses from China did meet UV protection requirements.

dcarch

By its nature, polycarbonate absorbs almost 100% of ultraviolet light. This would include greenhouse panels and sunglasses. The next factor is uv degradation of the plastic. To prevent that, additives with uv stabilizers can be added to polycarbonate. It is usually only added to one layer of the panels, thus the reason to place the correct side toward the sun. One method to try and help with the premature breakdown of some hfgh panels would be to cover the panels with a single layer of uv absorbing polyethylene sheeting. It is sometimes sold as "av" type, and has additives that even uv stabilized polyethylene is lacking. However, I have not been able to find a source for a hobby sized greenhouse.

My HFGH is a year and a half old. This is it's second summer. No sign of problems. I use shade cloth most of the year. $70 worth of shade cloth will probably extend the life of your panels for years to come.

If you don't use shade cloth, I'm not surprised that the plastic panels are breaking down under intense heat.

Who is the best vendor for a small order of polycarb in the midwest. I need 24- 2 x 8 panels. I know that I will need to have them shipped to us.
Thanks