Good point about the warranties! Hmmm, my GH roof is almost always covered with an endless supply of desert dust. I can hose it off, but it will be covered again in no time (in spring, anyway.) I have had a lurking concern that IF there is a panel deterioration problem, it may be heat related. I read a post on another forum last year from a Tucson GH owner who'd purchased two 6x8 kits to use the poly panels in his own homebuilt wood-framed GH. He posted that after a few years the roof panels were brittle and breaking. I know he doesn't use his GH in the summer at all, and I figured his roof panels must have been subjected to extreme temps (if it's 110° outside, imagine what it may be inside an uncooled GH in Tucson, especially the air right under the roof panels...140°? 150°?) I hoped my plan to use the GH year round might help me to escape the same fate (I'm hoping I can keep the temps in mine under 100°, although most of my plants will tolerate that.) Still, I note that the three mentions of this problem so far (the Tucson person, yours, and Jamesy40's) have all happened in southern states. If heat is a problem, mine will likely fail sooner than some...so I'm keeping an eye on this trend! I guess it could be an opportunity to upgrade the roof to 6mm at least, eh? :-) Sheri

In his blog about building his new 6x8 HFGH, dewey1945 shows how he applied 6 mil UV resistant plastic to the outside of his panels. I havenâÂÂt seen this idea discussed anywhere before, so IâÂÂm interested in following his blog: Apply the UV Resistant Skin When I replaced my roof panels in October of 2011, I applied a clear marine coating product to the outside of my new panels, before installing them. I also applied the same product to half of a scrap of HF polycarbonate (left over from installing my exhaust fan.) IâÂÂve left it exposed to the sun since October 2011. So far the treated side still looks shiny and clear, while the untreated side has started to look a bit dull and cloudy. Might be a good sign, but I think itâÂÂs still too early to tell if this product really does help. My cost to purchase a gallon of the product was around $100. The company (Top Secret Coatings) seems to have changed their product line since my purchase, so IâÂÂve emailed them to ask which product is the current equivalent of what I used. IâÂÂll post back here as with that info as soon as they reply. ItâÂÂs too bad we have to wait at least a few years to see if ideas like this truly will help extend the life of the HFGH polycarbonate panels. From my reading, folks in southern states with intense sun seem to report more panel failure. The topic hasnâÂÂt come up here at GardenWeb for a while, so IâÂÂm hoping that means folks in other climates arenâÂÂt having nearly as much of a problem. If you donâÂÂt do anything to protect your panels, and notice some problems in years to come, you can order replacement panels from Harbor Freight. The HF panels wonâÂÂt last as long as higher quality twinwall polycarbonate from other supply companies, (with real UV protection,) but they do cost a lot less. FYI, hereâÂÂs a summary of my pricing research from October 2011, for just enough material to replace the roof on my 10x12 HFGH, including shipping to my state: Farmtek 4mm twinwall polycarbonate, approx 10 yr warranty, about $410 Solexx 3.5 mm, (a flexible translucent white greenhouse covering material) about $350 Harbor Freight 4mm panels, $135 IâÂÂll be sure to post back with the Top Secret clear coating product number, so itâÂÂs recorded here for the thread.

Heat is a major concern with the Rion kits. Their warranty certificate actually indicates in writing that Rion's warrantly does not cover damage due to excess heat. So if you go with a Rion, you will need to pay extra attention to temperature management. The Rion 8x16 I recently built, straight out of the box is a sauna. At noontime with no clouds, it was in the 70s F outside and it was breaking 120 degrees F inside. Shade cloth, fans and other supplemental cooling is a must. The HFGH has some drawbacks straight out of the box too, but there is a wealth of information on these forums on how to reinforce them to make them sturdier and more efficient. The price is also nice. For the price of one Rion, you can probably build 2 or 3 fully outfitted HFGH of similar size. You could set them up on brick or concrete knee-walls. But bear in mind that these are already tall units to begin with. The Rion stands over 8 feet at the peak, the HFGH is pretty close to that too I think. It is something to think about if you are in an area with high winds. I like my 8x16 Rion kit, but it is still too early to tell if it will age gracefully or crash & burn (or melt). I am willing to be the expensive guinea pig for everyone's sake :) Some metrics: (**Disclaimer this is NOT an expert opinion**) *Price: HFGH Wins - price difference is very significant. *History/Shared knowlege: HFGH Wins - I have seen a lot more informative posts about the HFGH than Rion. Come on Rion owners, you gotta share the knowledge :) *Sturdiness (Stock): Rion Wins - Straight out of the box, the HFGH needs some significant shoring up. The Rion has very substancial structure. This is assuming that both kits are properly anchored to the ground. *Structural Integrity (Heat): HFGH? This is just based on the assumption that aluminum will be better able to withstand high temperatures compared to plastic/resin combos. * Dead/Live Load: ????? - Rion claims that their GH can support a snow load of up to 1100lbs. I do not have data on the HFGH - can someone please fill us in? * Aesthetics: Rion Wins - It sure is purrty! :) * Expandability: ????? This is an iffy subject. You can purchase additional Rion "middle modules" to expand the length of the GH in 4 foot increments. But the price of the expansion kits will probably match that of a whole HFGH kit. So the decision becomes "Expand the Rion? or Build another HFGH?"

johnnyq, I'm not much help, since I've been shamelessly kicking the can down the road for years now. Made it through the last two winters with a layer of 6 mil greenhouse plastic sheeting over my own badly damaged polycarbonate roof. We've replaced the roof panels once already, and I only get about three years in the HFGH panels before small holes start showing up in the outside layer of the roof poly panels (even with shadecloth in place all year.) I'm lucky we didn't have a wet heavy snow this winter, or we would have been out there rigging up emergency interior bracing! All of my wall panels are still original, and are now about ten years old. They've finally yellowed and developed small holes too, so I'm looking at a sizeable investment to replace all the roof and wall panels. To be honest I'm doing some soul searching about keeping the greenhouse, but I probably will go ahead with the replacement, since all is fine except for the panels. And I'm not sure I want to give up the hobby quite yet. My plan is to buy 4mm twinwall poly elsewhere (not Harbor Freight, as I'm just getting too old to deal with the work of replacing the roof so often.) Last time I checked, FarmTek seemed to be my best source price wise. Did you mean that HF is offering 6mm panels with a warranty now? One (potential?) heads up is there might be a slight glitch with getting 6mm thick panels to slip into the aluminum framing at the roof peak - as you know the panels slide into a channel up there - and there has been past discussion that anything thicker than 4mm might not slide into the channel easily. I don't know if this is a problem with the kits that are newer than mine, though, and it might not be an insurmountable problem. Maybe others will chime in with panel replacement updates.