Is Plastic better than Glass?

[MaggieM]

I see DIY greenhouses that always use some kind of plastic covering. One ad mentioned that their film had good light penetration, and the plants didn't get "glass burn".

Are there different kinds of film? How do all of these compare?

 

[Durgan]

http://www.durgan.org/URL/?HKERY 5 November 2010 Greenhouse on Deck.

I decided to build a large greenhouse on the deck, which doesn’t get much use. The enclosure will be a sun room if appropriate, instead of the canvas structure that use to be there. I have a small 10,000 BTU heater that connects to the barbecue natural gas outlet, so will have some warmth, and will get some use during the Winter months. It took nine days to build by myself, about 72 hours of labor, from 28 of October to 5 November, and cost $1798.63.

Description of the construction. Six, 6 by 6 pillars support the structure. The auxiliary supports are all 2 by 6 spruce planks. Two doors were installed plus a window to ensure reasonably good ventilation. I got the doors free of charge. The slope of the roof is from 8 feet to 7 feet, with a pitch of 1 in 12. Sun is available for about two third of the structure all day. Wood was used to cover the walls where no Sun penetrates. Corrugated SUNTUF UV protected panels was used. It is relatively low cost compared to other coverings, and is almost indestructible. Pictures depict highlights of the method used. Plans were in my head.

 

[Tjohn]

I see DIY greenhouses that always use some kind of plastic covering. One ad mentioned that their film had good light penetration, and the plants didn't get "glass burn".

Are there different kinds of film? How do all of these compare?

From my experience, the plastic is better than glass as it does not focus the sun's rays quite so intensely in the greenhouse. My first year we had glass and my poor plants looked like those ants we killed with glasses in grade school. The plastic Lexan panels do a much better job.

 

[Esther Knapicius]

from the stand point of mother nature, plastic is not bio degradable. where as they can do a lot with unwanted glass.

 

[SirJoe]

I think that plastic is the better choice, you can get it in transparent or opaque and it's much lighter and easier to work with then glass. This also means that the glass house doesn't have to be the traditional shape and at the end of it's working life it can be recycled.

 

[MaggieM]

http://www.durgan.org/URL/?HKERY 5 November 2010 Greenhouse on Deck.

I decided to build a large greenhouse on the deck, which doesn’t get much use. The enclosure will be a sun room if appropriate, instead of the canvas structure that use to be there. I have a small 10,000 BTU heater that connects to the barbecue natural gas outlet, so will have some warmth, and will get some use during the Winter months. It took nine days to build by myself, about 72 hours of labor, from 28 of October to 5 November, and cost $1798.63.

Description of the construction. Six, 6 by 6 pillars support the structure. The auxiliary supports are all 2 by 6 spruce planks. Two doors were installed plus a window to ensure reasonably good ventilation. I got the doors free of charge. The slope of the roof is from 8 feet to 7 feet, with a pitch of 1 in 12. Sun is available for about two third of the structure all day. Wood was used to cover the walls where no Sun penetrates. Corrugated SUNTUF UV protected panels was used. It is relatively low cost compared to other coverings, and is almost indestructible. Pictures depict highlights of the method used. Plans were in my head.

Pretty awesome! I'm wondering, what temperature do you keep it at in the winter? And do you do anything special for humidity?

 

[Durgan]

Pretty awesome! I'm wondering, what temperature do you keep it at in the winter? And do you do anything special for humidity?

I try to keep the temperature in the worst case just above freezing, but I like it around 70F if at all possible. I find it is not necessary to add humidity, but I have used a small humidifier in the past before abandoning it.

 

[TheBeardedGarden]

There's a great YouTube video about plastics. The scene opens up on a high class party, an older gentleman pulls aside an upcoming businessman and tells him outside, "When I tell you this one word, this one product is going to change the world. Plastic." Scene closes.

Plastics are a god send, they get a terrible wrap from the media and focus groups and a good chunk of plastics can be recycled. They are moldable to what ever you need, the applications can be as simple as a safe toy for children to an intense product in aerospace.

Glass is expensive to make and produce. To put them in a green house you need them to be tempered which adds a great deal of cost. When tempered glass becomes much stronger, and when it breaks it'll safely shatter to smaller pieces, which will cause less damage, if any at all, to what ever is below it.

To make glass you mix about 90% sand (silica) and other common minerals and throw them in to a fire bed at temperatures close to 600°c iirc, to temper glass it gets up to 1400°c and cools to 100° in about 5-10 minutes AFTER the glass is made.

Glass weighs more than plastics. Glass doesn't really filter light, if you can get it polorized you can cancel out certain wave lengths. Tints help filter wave lengths as well.

Plastics are extremely inexpensive compared to glass, an average of $1.66 can be applied to per sq.ft of plastic coverage on a 6mm twin panel of polycarbonate, where on tempered glass you're looking at $25/sq.ft.

Plastics are extremely durable, polycarbonate can withstand minor hail storms! You can add different compounds (like you can with glass) and change its chemical structure and make it even stronger, at an marginal increased cost, or just thicker for an cheaper increase.

Plastics are extremely light weight, I am ordering a 10'x10' 6mm twin wall polycarbonate and it weighs in at maybe 100# where a similar glass is maybe 300# so there's a MAJOR shipping's saving.

Plastics are naturally UV resistant and transmission of UV is about .01%, plants use the majority of the yellow spectrum for photosynthesis, so you won't get leaf burn with plastics - only down side is a lot of 'natural sterilization' is by UV light.

Plastic is more flexible than glass too, if. You're needing to bend it for what ever reason, just know you are creating a stress point which may break in the future.

My votes plastic. Hands down.
But if you got the money to blow, glass looks more... Classic? Elegant? Bragging rights?

 

[Daren]

for me if someone was offering me a glass or plastic greenhouse I'd take the glass for its longevity. But I have seen plastic greenhouses that work well can cost a lot less. I got to say on the side of glass I see loads of adverts by people on EBay here in England giving there glasshouses away for next to nothing the only thing they want is for the collector to dismantle......That's the hard bit often & moving them without Breaking half the glass !

 

[TheBeardedGarden]

for me if someone was offering me a glass or plastic greenhouse I'd take the glass for its longevity. But I have seen plastic greenhouses that work well can cost a lot less. I got to say on the side of glass I see loads of adverts by people on EBay here in England giving there glasshouses away for next to nothing the only thing they want is for the collector to dismantle......That's the hard bit often & moving them without Breaking half the glass !

That's a path I didn't think about going - then again, a good polycarbonate will last 10-15 years. At almost 1/3rd the cost you can theoretically buy 3 green houses in your life time or one, with a few replacement panels.

It depends xD I'll need to check my eBay

 

[MaggieM]

Hey, I gotta tell you guys. I did end up with a polycarbonate & aluminum greenhouse.

It gets windy here sometimes. 50 mile gusts across fairly open land. Even with extra clips and that caulking stuff (which really didn't adhere too well when applied in cooler weather), the panes blew out all over the place. Those panes did survive pretty well though! Only a few minor crunches. I'm saving them. And I say that I'm saving them because the aluminum frame itself was completely twisted, ripped, and trashed.

I think it would be a good greenhouse if it's placed in a more suburban or urban area where the wind gets broken up by buildings and doesn't have the chance to accelerate.

 

[TheBeardedGarden]

That's unfortunate :/, if you get constant winds there are trees or shrubs that are thick and dense to help break up those winds.

The other day we had a wind storm with like 80mph gusts knocked over a tree! But hanging out in my back yard that's surrounded by thick shrubs and tree, it was maybe 15-25 mph gusts.

Are you going to try again and rebuild? Make some adjustments in the build, and maybe plant some trees outside to help block it?

Typically if you're going to do a wind block with trees you'd need to do it along the property line, a quick Google search can show you what is ideal plant wise for your growing zone.

 

[MaggieM]

Gosh, you know what? There actually is an established woods here. But you've given me an awesome idea. Maybe some pines could do a better job of breaking up the wind.

As far as rebuilding goes, well, I don't know. I think I'd prefer wood next time, but I am liking the plastic over glass argument.

 

[TheBeardedGarden]

Don't be discouraged to rebuild - it's only a failure if nothing was learned.

To me it sounds like the greenhouse was open and wasn't secured to the ground, nor the frame too well.

So it cought the wind and flew.

 

[Rec0n]

where did you end up buying your plastic from? im looking for some good polycarbonate that will last maybe at least 5 years