Glass vs Polycarbonate vs Film

MoonShadows

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#1
I was just reading on another forum where a member wrote about buying his first greenhouse...always a fun project! The one he has picked out is glass. This got me to "preaching" so to speak, so I decided to make this post on our forum.

There are different types of glazing (greenhouse coverings) you can choose. Each have their advantages and disadvantages, and which one you choose will depend on your particular climate, aesthetic preferences, and budget.

GLASS
Glass lasts forever and has the clarity to allow you to clearly see and enjoy your plants even when outside the greenhouse. Glass is the "traditional" look for a greenhouse. However, glass is very fragile, and can easily break from an unexpected bump or knock. Glass has a real potential to burn or scorch your plants due to it's clarity. It also has a poor thermal efficiency (3mm glass R=0.95 and 4mm glass R=1.0). If you decide to go with glass, make sure it is tempered safety glass. While tempered safety glass can still break, you won't have the dangerous shards if the worst happens (think car windows-crumbly glass). 4mm is much stronger than 3mm, so think about spending a few extra dollars for safety's sake; you'll be glad you did. An alternative to glass is clear sheets of polycarbonate. It has all the advantages and disadvantages listed above except it is very strong and will not break like glass.

POLYCARBONATE (walled)
Double and Triple walled polycarbonate is extremely durable and strong, almost impossible to break. It has the best thermal efficiency of the 3 greenhouse coverings (6mm Twinwall R=1.54), and offers better frost protection keeping warmth in longer into the night. It diffuses sunlight which helps prevent burning or scorching of your plants and aids in photosynthesis, and has good longevity as long as you get premium polycarbonate with a UV coating applied. However, polycarbonate is prone to scratching and should never be cleaned with anything more than mild solution of dish soap and a very soft brush or cloth. Moisture, mold and bugs can get into the flutes if they are not properly sealed at the ends. If you choose polycarbonate, make sure it is not recycled and has been made from virgin materials by a reputable company, and make sure it has been UV treated which increases it's longevity.

FILM
Film is the least expensive of the greenhouse coverings and because it has some give, it can take mild bumps and knocks. Like polycarbonate, it is good at diffusing sun light which prevents burning and aids in photosynthesis. However, film has a relatively short life and needs replacement. Even top of the line film only lasts about 4 seasons before it needs replacing. It has the poorest thermal efficiency of the 3 coverings, and is prone to rips and tears. If you decide to go with film, don't go the cheap route and just buy plastic from your local big box hardware store. You'll regret it. Save yourself headaches and buy a 6mil thermal, anti-condensate film. If you leave it on more than 3-4 years before changing, it will turn a milky-white, and your plants will suffer.
 
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MoonShadows

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#3
Most welcome....Besides writing regular posts and responding to others, I am trying to take some time to write some more "formal" posts and resources. Not only will they serve as a repository of knowledge, but they also help with SEO for our young forum in a sea of greenhouse topics on Google and other search engines.
 
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#4
I have the Palram single layer polycarbonate. Very clear. My smaller greenhouses came with the dual wall and for purely esthetic reasons I ordered all new clear single layer panels. Had to take them apart to then put these in.


My biggest concern with glass is that the ones that are double glazed could also have seal problems and the look of vapour in between really is unsightly.
 

MoonShadows

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#5
Double-insulated glass greenhouses should be fine unless something compromises the seal....Just like house double insulated windows.

Originally, I was concerned with the "look" of a greenhouse, not only the "beauty", but being able to see into the greenhouse from the outside (think: clear), but as I go on, I find I am less in interested in aesthetic "beauty", but what glazing is best for accomplishing my greenhouse goals.
 

jordan

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#6
Hi Lori...Palram is one of the greenhouses on my list. Which model is that one you have?

I really like the Bella, but it is out of my price range. I am thinking of the Snap and grow.

Bella
palram-greenhouses-703730-64_1000.jpg

Snap & Grow
palram-greenhouses-701273-64_1000.jpg

I only have about 2 dozen greenhouses on my list....LOL...I have to start narrowing down the list.
 

waretrop

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#7
I have to put my feelings in here, I don't know why. I don't care for anything but glass. I am just stuck on it. My husband wanted to replace out glass with, well, something else, but I wouldn't even hear him.

It costs me more, I am sure. The greenhouse you see in my avatar is single walled to boot which is even worse. :( but I don't care. I love the looks of it and this is for my hobby flowers not for a business.

I also have a little 5x7 one with that corrugated plastic panels in it. I hate it. It is probably 15 or 20 years old, maybe more. It has discolored and is very brittle now. I will be putting glass panes in it next summer. I also have a large lean-to exactly the same brand of my large one. I have not put the glass in yet. It was used and has double pane glass in it which the seals have been compromised. I will put single pane glass in itt also next summer. We waited to put the glass in until we have a new roof. Don't want to break any glass while taking off the old roof.

Anyway, just wanted to add my feelings on this subject. I think you have to like the looks of it for what I am doing. I love mine even though I pay for it.
 

MoonShadows

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#8
Good post. I think that is one of the considerations one has to make in getting a greenhouse....the aesthetics...the look you want from the outside. And, for every choice one makes on a greenhouse, there may be a tradeoff. I would love to have glass, even thought of getting it, but didn't for one main reason; when I bought our greenhouse, we couldn't afford the glass and the clear polycarbonate sheets were the next best choice. Also, the greenhouse I wanted did not have a glazing option. There are advantages and disadvantages to any glazing...for that matter, there are advantages and disadvantages to any part of the greenhouse structure.