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Greenhouses & Garden Structures

HFGH vs build a wood framed greenouse

13 years ago

I am weighing the option of buying a 10x12 HFGH vs building one covered in 6 mil plasic film. Which one will hold heat better in the winter? Any input siding with one or the other would be great. Thanks in advance!

Comments (7)

oakhill (zone 9A, Calif.)
13 years ago
In general, the double layer polycarbonate on the HFGH will require about one-half the energy for heating as compared to a single layer of polyethylene. If you use a double layer, air inflated, polyethylene, the heat requirements get close to the same compared to the HFGH.
Mike Larkin
13 years ago
build it and make it double poly , Seems to be so many problems with HFGH - do a search on this site and then decide.
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Great pictures! Fortunately, the tree in our way died about a year before we put up our greenhouse (still had to cut it down, though!) We had a furry OSHA inspector too (all extra paws and hands were greatly appreciated.) I love my 10x12 HFGH, enjoying it for my third year. It's totally stuffed with plants, year round. "- We will add more clips to prevent the panels from flying off in the wind - a major concern." Sounds like you've read the archived threads here about the recurring problem of lost HFGH panels. In addition to extra clips (we did that too) it's pretty easy to add self-tapping screws to the panels, as even more protection against panel loss. The 10x12 is pretty tall and makes an even worse target for wind damage, but there are some scary threads archived here about wind-damaged 6x8 HFGHs as well. Here are some photos showing how we screwed the panels into the aluminum frame (thanks to previous GardenWeb forum members who suggested this improvement.) Part Six, Adding the Panels "- Depending on the temperatures, may add a blind on the western end to prevent sunburn and excessive late afternoon heat." I definately need shadecloth on the roof, west end, and south side (my succulents and cacti cook in there without it.) I also believe that adding shadecloth has helped to increase the lifespan of my HFGH panels in our sunny climate. (I used Aluminet shadecloth.) Some GardenWeb HFGH owners have reported problems with the HFGH panels deteriorating after exposure to sun, but others don't seem to have this problem. My panels have yellowed, but I see no other signs of deterioration (fingers crossed.) "In winter, may add water jugs as heat sinks in cooler weather." In theory it seems like this would help, but the general consensus seems to be that you'd need very large containers of water to retain enough heat to truly benefit you into the wee hours of a cold morning. Most small greenhouses can't afford to give up the high percentage of space required to make this work, but there's lots of good reading on this topic in this forum (posted by folks who are much smarter than I am.) "- Wish list: shelves, solar fan, temperature activated window control" Just a warning, the HFGH solar fan is not powerful enough to adequately cool your greenhouse (sounds good, but doesn't quite work.) If you do a search in this forum for HFGH solar fan, there's a thread with a knowledgeable poster sharing his calculations that a 6x8 HFGH would need three of the HFGH solar fans to exchange enough air to drop the temps (if my memory is right.) There are also some posts from folks saying the HFGH vent openers don't last long at all, and it's best to research and purchase other brands that have a better track record. Good job, congratulations, and happy greenhousing! Sheri
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mudhouse_gw
13 years ago
My HFGH 10x12 has been up for three years. For me, it's been a great way to try greenhousing without investing tons of money. However, I don't recommend building it without reinforcements to help prevent panel loss in wind (there are some sad stories in this forum about what happens without reinforcements.) Many forum members have shared inexpensive HFGH reinforcement tips, and I've gathered some of those ideas in my blog below. Our GH withstands heavy winds routinely with no problems.
Building our Harbor Freight 10x12 Greenhouse

Some HFGH owners find the Chinese-manufactured twinwall polycarbonate panels deteriorate prematurely (HF offers no warranty.) This seems to happen more often in sunny southern locations. Some HFGH owners in this forum don't have this problem, and shadecloth use seems to help.

My panels developed obvious yellowing about two years out, and will need to be replaced next spring. Panels unprotected by shade cloth have developed 1/8" to 1/4" size holes on the outer poly wall (4 to 10 holes per wall panel, I just patched them yesterday.)

Structurally the GH is great, so I'll purchase 4mm twinwall polycarbonate or 3.5mm Solexx panels elsewhere to replace the failing HF panels. Replacing all panels will cost about as much as the initial GH kit itself three years ago, but other manufactured kits of the same size are still a lot more expensive, so I don't regret the purchase at all.

This website's heating calculator lists the various heat loss values for a range of greenhouse covering materials, so you can compare them. (The Harbor Freight twinwall polycarbonate panels are 4mm thick.):
Greenhouse Heater Size Calculator

Hope this helps a bit.
web4deb
13 years ago
I really like my HFGH 10x12. In a weekend you can have it fully assembled. It's unlikely you can build your own for the price.

You can look through my videos at http://www.youtube.com/web4deb and also my blog at http://web4deb.blogspot.com
erlyberd
13 years ago
Build your own and make it the way you want it. It really depends on what your looking to grow, in what season and how good your handy skills are.

If your serious in building a greenhouse look into passive solar greenhouse practices and incorparate these techniques into the overall plan. You need to keep a small surface area to retain heat. Try a pit house or attached structure.
eaglesgarden
13 years ago
I would think that it would be easier to insulate a custom built greenhouse. After all, there really is no reason to have glazing on the north side of the greenhouse. All that will happen there is a loss of thermal energy. If you build a custom structure, you can build a solid/opaque north wall and insulate it, so that there is not a huge energy leak out the north side. This is probably also cheaper in the long run than glazing on the north wall, which will need to be replaced eventually. A solid wall wouldn't need that. This could also cut your glazing costs, and allow you to purchase a higher grade/better insulated glazing for the east, west and south sides.
knotbored
13 years ago
I have a HF model-reinforced as sugested by these forums and couldn't be happier after one season.
I am considering placing a cheap greenhouse like ShelterLogic inside the HF model next winter to try overwintering veggies. The double walls should provide better heat retension then even a single insulated wall, and the price is pretty inexpensive.
I will disassemble it over warm seasons and use it to protect tomatoes from fall blight (a serious problem in my moist climate in WA state.)

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