Potential problem with Harbor Freight greenhouse panels?

We put up a 10x12 Harbor Freight greenhouse seven months ago, and I love it! It required some modifications for strength, but those weren’t difficult or expensive. It’s done everything I wanted, and more, for a very reasonable price. I could not be happier!

However, two people from southern states have recently posted on another website about deterioration of the polycarbonate panels supplied with the Harbor Freight 10x12 kits. The problems (yellowing, and the development of small holes) have surfaced one to two years after purchase, and so far seem restricted to greenhouses in hot/sunny climates.

The Harbor Freight website currently describes the twinwall, 4mm polycarbonate panels included with the kit as “UV coated polycarbonate panels, nearly indestructible."

Because I’ve been maintaining a blog about constructing these affordable greenhouses, I emailed Harbor Freight customer support in early May.

My question 1: Do the Harbor Freight polycarbonate panels have UV protection on both sides, or on one side only, or no UV protection at all? There is no mention of any "right" or "wrong" way to install the panels in the manual...and no way to tell the two sides apart.

Harbor Freight's reply to question 1: "The greenhouse only has a small amount of UV filtering through the panels. To have the manufacture increase the UV protection would increase the cost of the greenhouse to us and our customers."

My question 2: Have you folks received complaints about the apparent deterioration of Harbor Freight polycarbonate panels after only one or two years in service, including yellowing and specifically the appearance of small holes?

Harbor Freight's reply to question 2: "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."

For more information, here’s an ongoing thread in another forum that explains how this question has come to light::
http://forums2.gardenweb.com/forums/load/strucs/msg0410080322640.html?65

I think it’s really too early to tell how widespread a problem this may be, and I wish I had more complete information to share. But, I don’t feel right about not sharing this concern with others here. Polycarbonate panels are expensive to replace.

My Harbor Freight greenhouse panels (7 months old) still look fine, but I’m on a sharp lookout for problems. If the reported panel failures in the above thread are not some kind of rare manufacturing fluke, and if they’re instead related to inadequate UV protection from heat/sun exposure, my little greenhouse in hot southern New Mexico should be a prime candidate for early panel failure.

We’ll see what happens, but I thought it was best to let folks know about this unsettling development, in case others in hot climates are considering making a purchase in the near future.

I’ve also updated my Harbor Freight greenhouse blog to include this new information:
http://hfgh10x12.blogspot.com/2007/08/this-is-greenhouse-we-bought-link-it.html
Sheri

Looks like I might better save some money for replacement panels of Solexx? Here in the Phoenix area I have an even worse problem as we have more intense heat days as well as smog deterioration possibly. I do have layers of shade cloth most of the year that limits the surface area of exposure, maybe a good thing for the panels. Mine is less than one year old so time will tell.

Ron

Sorry to be the bearer of potentially bad news, Ron. I have probably doomed my own panels to an early death, because my husband and I installed our Aluminet shadecloth on the inside instead of the outside, to avoid our awful winds. My guess is (all just guesses at this point) that shadecloth would slow the deterioration. Should we move it now after already being exposed for 7 months? Still deciding.

I'll update this thread as I learn anything new. I suspect that folks with Harbor Freight greenhouses will apply the same ingenuity to this problem as they did to erecting them, so maybe we can help each other by sharing sources for replacement panels.

One challenge will be finding panels that fit into the channels in the door panels, vent windows, and the roof. The thread in the other forum (link above) has more on that, as one person in Texas has ordered 8mm heat reflective twinwall poly panels from Charley's Greenhouse supply. He'll have to be creative in modifications to the panels to get them to fit the channel at the crown, but he's great about sharing his experiences with photos. On we go.

I still love mine; the design of the HF has allowed me to build replacement screens for the south wall, which seem to really help with our hot temps here. I know it's an entry level greenhouse...I was just planning to get more than one year out of the panels! Time will tell, as you said. ;-)

Solexx sells 3.5 mm panels and 5 mm panels and I saw it in rolls somewhere also. Of course with the price of petroleum going crazy I may never be able to afford any by the time I need it!
Another thought, I used to buy a clear ultraviolet inhibiting spray or liquid for my commercial houses years ago. Used to mix it with cheap white paint for summer shade and applied it with a pump up sprayer. I brokered tropical foliage so shade was desirable most all the time here. Applied it to Filon fiberglass.

I have a hunch that the pin holes and discoloration is a result of chemical out gassing as much as it is the solar effects though.

Ron

I'll look into the Solexx.

Would you have a brand name for the UV inhibiting spray or liquid? I've not been able to locate similar products by Googling.

One GW member contacted a polycarbonate supplier, who said that this Plasti Dip product can be applied to polycarbonate. They offer a UV clear version, so I may try to locate a source (no idea of cost yet.)
http://www.plastidip.com/home_solutions/Plasti_Dip

I'm not knowledgeable about the chemistry behind polycarbonate panels. I'm assuming these are manufactured in China, along with the rest of the kit. I gather that outgassing is the release of moisture or gasses that are trapped in a substance during the manufacturing process. Would a poorly (cheaply) manufactured polycarbonate panel trap larger amounts of moisture/gasses inside the material (meaning, a "dirtier" product?) Then, these trapped substances could be triggered to outgas when exposed to UV...more rapidly in sunny/hot climates than cooler ones...so the escaping gasses could cause the holes to develop?
Sheri

Out gassing can be anything from poorly mixed concoctions to environmental considerations such as heat and light waves. It happens to almost all plastic products and can take from minutes to years depending on the situation. Every compound has the possibility and materials that have low out gassing are typically very expensive and usually are manufactured for special uses like space. Out gassing is the reason that plastic lid doesn't fit the box any more
I don't have a name but will ask my plastics engineer if he can find something for us that we might use without breaking the bank or ruining our poly.

Ron

Thanks for the info Ron. Any help is much appreciated!

Update -- late today I removed a south wall panel and replaced it with an 18" scrap of panel that we removed when we installed our exhaust fan 6 months ago. (The scrap has been stored indoors, away from the sun.) I taped white paper behind each panel to look for yellowing. Yep, after only 7 months, my panels are starting to yellow. I'll take a pic tomorrow in better light and post back.

I did a search and ran across this company that has something interesting in UV coatings. I don't know anything about this stuff but you might call them.
Ron

http://www.sublimationink.net/uvextreme.html

Here's a photo of my 18" scrap (only exposed to one month of sun) held up to my roof panels. I sprayed the roof with distilled water to wash off any dust. Not sure if you can see it in the photo as well as I can see it in person, but I can see the beginnings of a change. The scrap retains the original blue-clear color, but the panels on my greenhouse appear slightly less clear, and more yellow in tone.

This is after 7 1/2 months in southern New Mexico sun (intense sun much of the year) with occasional temps over 100°. I'll take more pics periodically to record any progression.

Just thinking here;
I think that the holes might be caused from space gravel. I know it isn't often discussed but there are tons of particles that reach earth daily and if it were to hit the now brittle plastic it could cause just such a hole. there wouldn't be any reason for the plastic to just disappear unless it was contacted by some other material. I just asked my plastics engineer to find us a usable UV inhibitor. Keep your fingers crossed.

Ron

Ron, thanks, I have all ten fingers crossed. (Makes it hard to type.)

Here's a link to some pics just posted by the person in TX who is replacing his roof. The edges look sharper than I'd expected...like an impact of some sort. The other person who reported holes has not returned to that forum, unfortunately, so no pics to compare.
http://s124.photobucket.com/albums/p12/laserfan/10X12%20HFGH/Details/

The company you listed above says they're no longer carrying the UV inhibitor products listed in their website.

Yesterday I researched UV blocking window films. The ones sold at the box stores here are by Gila Films (http://www.gilafilms.com/) and they do have a great range of products, and excellent response to questions. Some of their films block all UV, in either clear or a range of tints. Unfortunately, their support dept says the films absolutely can't be adhered to any plastic product (will turn milky and bubble, and will become embedded into the poly surface itself, etc.) We could leave the clear backing in place and find another way to affix the film to the poly panels (UV resistant rubberized construction tape along the edges?) But, it will only last 2-3 years in exterior applications.

So, figure 2 years max in our hot climates...about $12-$15 per roof panel...reapplied every two years (let's not underestimate the hassle of taking the roof apart.) I might be better off to just buy new 4mm panels with a 10 year warranty. It's still a possible solution to buy some time, and the product would be easy for folks to find (online store) but I was a bit disappointed in the lifespan of the product, and it would be problematic to install. Problem is, we're not using it as intended; used indoors, it has a 10 year life span.

I'll look into the UV clear formula of Plasti-Dip next.
Sheri

My plastics engineer didn't find anything useful. He did suggest possibly using a wax (auto) that has UVI in it's components though. I will keep looking.

Ron

Look into aerospace 303 protectant as it looks the most promising so far with high UV protection and won't hurt plastic (thier words)

Ron

So it appears there is NO UV protection on the HF GH panels?? Am I reading that correct?

Argh!! Throws a monkey wrench into my plans!!

They supposedly do have UV protection, I think a few people out there have had experiences that would suggest maybe there's not enough of it on there but I don't know if there's anything conclusive one way or the other at this point.

I have to agree with ecrane3 at this point. Given the number of hfgh houses out there the few problems with discoloring and holes can only be considered an anomaly of undetermined cause. In engineering circles it is a "possible unverified failure" until a root cause can be established. I know that doesn't help people with apparent issues but jumping to an easy fix for a problem often has unintended consequences so don't be too hasty. It may be something about only one lot of panels made during a certain time period or even a poor chemical application to a few panels. It might even be something as simple as waxing the panels with carnuba wax periodically to slow the out gassing and retard the UV degradation assuming that is the problem

Ron

I sure hope that’s right. There is nothing conclusive at this point, but the bad thing is, there probably won’t be for several more years, until we see how frequently the problem pops up.

The list so far:
- Texas 10x12, 1 year, roof panels brittle, yellowing, holes (see link above for pics)
- Arkansas 10x12, west and south walls developed cracks and holes after 2 years (subsequently destroyed by hail)
- Utah 10x12, panels yellowing and becoming brittle after 2 years
- Western Pennsylvania 6x8: yellowing after 2 years, holes and further yellowing after 5 years.
- Arizona 6x8, roof panels becoming so brittle after 3 years they broke upon touch.
- New Mexico 10x12, my own panels begin to yellow after 7 months.

Frankly, two things bother me a lot more than the above list. First, Harbor Freight's answer to my carefully worded question (above.) When I asked where the coating was located (one side, both sides, or no coating at all?) they ducked the question, referring only to general "filtering" through the material (which happens with uncoated poly.) If there is a coating, why couldn’t they just tell me where it is?

Second, I’ve read UV coated panels are usually only coated on one side (costs more to coat both sides, and there's no need to coat the interior.) People tell me that UV coated panels come with markings on the plastic, so folks know to install the coated side on the outside of the greenhouse, facing the sun.

Harbor Freight panels have no markings to indicate which side is coated. Both sides have clear protective plastic. The manual doesn’t state which way to face the panels. People have posted that HF customer support told them it doesn’t matter which side faces out. That would only be true if 1) neither side had a coating, or if 2) both sides did. I can’t believe penny-pinching Harbor Freight would provide UV coating on both sides of their inexpensive Chinese import greenhouse panels, if better greenhouses only coat one side. Eh?

Regardless, seeing the yellowing on my own greenhouse would seem to indicate my panels are not performing as they should. Most of the UV coated poly panels I’ve looked at have a 10 year warranty against yellowing. I agree that taking action has consequences, but if I wait too long to protect them, the risk is I’ll be buying new panels like my friend in Texas. Rock and a hard place!

Aerospace 303 product came up in another forum. One member who restores classic cars says it costs $60 per gallon, and would only last a few weeks (less if raining.) He joked that $200 per month would protect our greenhouses…?

Thanks for checking with your engineer, Ron. I have found one clear UV coating that the manufacturer says will work, but I’m still checking into it. Will post back. :-)

I wonder if you could use some of the cheaper automotive protectant sprays--there are some that are designed to be used on vinyl/plastic dashboard materials to protect them from UV degradation. I'm sure they'd wash off and need to be reapplied after rain or if you live in a dry climate like mine you'd probably have to reapply once a month or so even without rain, but you can probably get a bottle of it for under $5 so it might not be a bad solution (assuming it would provide enough protection, which I have absolutely no idea).

Just a side thought;
Here is AZ when a company guarantees shingles for 20 years, we plan on replacement in 10-12. Warranting a product is usually a gamble on the manufacturer's part and he is playing the odds to his benefit. I believe that even solexx brand panels won't last 8 years as warranted so it is silly on my part to think a Chinese made plastic would perform on anything even close to something properly manufactured.

I have the 6x8, three years so far. The panels are not yellowed yet, but they aren't as clear as they were. We get a lot of summer heat, so I am thinking they won't last forever anyway. I am worried about them getting brittle and cracking. If they do go eventually, I'll probably use plastic film to cover the frame. I hope to have a bigger greenhouse by then anyway. (Hope can't hurt, can it?)

My sister has one of those preformed fiberglass greenhouses. It is coated with Gelcoat...came that way.
There is a marine wax that you apply over the Gelcoat since the Gelcoat is sensitive to UV rays.I wonder how it would work if put on yearly and prior to building the HFGH??What do you think??
Here is what it says in the description for just one brand [there are lots of them if you Google]of the wax about what you can use it on and UV protection:


Flitz Waxx Protectant is a White Carnauba and Beeswax Formula that provides Exceptional Results on ALL Painted Surfaces, Clearcoat, Gelcoat, Lacquer, Polyurethane, Fiberglass®, Plexiglas®, Eisenglass®, Acrylics, Plastics and Much More. Available in two sizes.

Removes and Protects Against: Rust, Fingerprints, Water Stains, Tree Sap, Salt Deposits and Lime Deposits. Contains no Detergents. Primary Purpose is to Offer Great Protection and High Luster. Protects up to 9 Months in Fresh Water and 6 Months in Salt Water. Will not Attract Dust or Wash Off in Rain. Water-based. Contains no Solvents. UV and Acid Rain Protection. Easy to Apply and Buff Off.

Here is a link to a different kind.
http://www.babesboats.com/techGelcoat.php

This message was edited Jun 25, 2008 12:16 AM

What about something like this product?
http://www.theplasticsdoctor.com/

Thank you Robin24, that Boat Bright product in your first link is pretty interesting, and sounds like it would provide some UV protection. My problem with products that need to be applied regularly is the tall roof…10 ½ feet at the peak. The only way I could apply a product that requires rubbing would be to remove all the roof panels, treat, and then reassemble… and that's a major job to repeat regularly (especially since my GH is full year round.) I also wonder if the extreme sun here would require more frequent applications than in some climates?

The jury is still out, but I’m getting ready to apply a product I ordered from this company. It’s a clear one-coat epoxy finish with UV protection, and should last for years without reapplying.
http://www.topsecretcoatings.com/ts-100_1-part_epoxy_clear_4849362.htm

I worked a lot with the (patient) sales rep, and for a small fee they increased the amount of UV protectant in my gallon (no info on what % of UV blockage.) They say it’s safe for use on polycarbonate, although not specifically designed for greenhouses. It goes on very thin, so one gallon should do the roof and walls of my 10x12. With the thinner and shipping, it came to a bit over $100, so I thought it was worth a try.

I'll start applying it to my panels soon, with a roller. I may try to coat the roof panels in place with a long handled roller in the evenings (best not applied in temps over 90°.) If it works, maybe folks could use it on new HF greenhouses before erecting, for UV protection? Problem is, I won't know for many months how well it has worked (if at all.) I plan to take periodic photos to monitor how my panels look in the months ahead.

Beclu727, I’m so glad to hear you've gotten three years of good use from your HFGH! I agree, these inexpensive greenhouses can be a good stepping stone to larger ones. My HFGH has been a great way for me to learn.

I've just added exterior shadecloth to my roof, west wall, and west doors, in an attempt to further protect the most sun-exposed panels. (I had it hanging inside previously, so it did not protect the panels.) Do you use a shadecloth? Some folks I know say it seems to help if you keep the greenhouse covered, even if not in use, so that might be something to consider...?
Sheri

Sheri - I had shade cloth over mine the first 2 summers. I think that makes a difference. I didn't put it up this year because the GH is empty and I was lazy. I moved everything to my shed porch for the summer as that porch is in full shade most of the day. Without the shade cloth, I bet those panels will age more this summer. Becky

Thanks Becky, then your experience fits what others have posted too. One person I know keeps a 6x8 covered with a sheet when it's empty during the summer...not even a true shadecloth...just so the panels aren't directly exposed.

Since I didn't know about any panel deterioration problem 8 months ago, my plan was to avoid the hassles of shadecloth on the outside in our high winds...but doing so probably caused my panels to age faster. :-( The person in Texas whose roof panels developed holes in a bit over a year didn't use a shadecloth either; people who have used one from the start seem (generally) to notice fewer problems earlier.