Which side? It is perfectly clear.

[dcarch]

I have seen this question posted many times in many boards.

Greenhouse polycarbonate insulated panels are expensive. How can you tell which side is UV protected, if you get the panels mixed up?

I don't remember if anyone has a way to solve the problem. If you do, please share.

Here is what I have come up with:

1. Buy a "black light" (UV light). you can get one from $10 to $20. Or you can just buy the tube if you have a portable fluorescent light. Cheaper.

2. Steal some fabric whitener powder from your wife (or husband ).

3. Pour some whitener in the panel's cavities.

4. In a darken room, shine the black light on the panel. The clear side without the UV protection will be slightly brighter.

LED UV black light will not work very well becasue the wave length is not short enough.

dcarch

[robin303]

Priced the panels the other day at $62. a sheet.

[bbb123]

holy sheet!!!!!!!

[dice]

Note that cheap, generic 6-mil plastic is usually figured
for a longevity of at most 3 years, and no more
than a year or two more for professional 6-mil greenhouse
plastic on rolls.

dcarch probably expects his polycarbonate panels to
last at least a decade, maybe longer.

[bbb123]

I'm thinkin about building a hoop house I have several of those car ports 2 are 10'x20' and a 20'x40' "tent". The big one is to big I think, but could I rap the small ones with greenhouse plastic? I'm worried about wind cause they are not meant to have sides. Maybe put some cross support to stiffen it up a little? Any ideas or comments would be welcome thanks.

Bill

[dcarch]

Originally Posted by bbb123

I'm thinkin about building a hoop house I have several of those car ports 2 are 10'x20' and a 20'x40' "tent". The big one is to big I think, but could I rap the small ones with greenhouse plastic? I'm worried about wind cause they are not meant to have sides. Maybe put some cross support to stiffen it up a little? Any ideas or comments would be welcome thanks.

Bill

Show a picture.

dcarch

[bbb123]

I don't have anything up yet. The car ports are the ones they sell at Lowes and Home Depot its just a metal frame I think the frames are 8' apart. They come with a tarp that you use small bungy cords to attach to top (peak) of frame. I just wanna use the frame. Here is a picture of one similar to mine.http://www.farmtek.com/farm/supplies...1020PCW10.html

[dcarch]

Originally Posted by bbb123

I don't have anything up yet. The car ports are the ones they sell at Lowes and Home Depot its just a metal frame I think the frames are 8' apart. They come with a tarp that you use small bungy cords to attach to top (peak) of frame. I just wanna use the frame. Here is a picture of one similar to mine.http://www.farmtek.com/farm/supplies...1020PCW10.html

Where are you in NY? I am in NY Westchester.

It doesn't look like it can withstand the wind without reinforcement.

dcarch

[bbb123]

Coxsackie, NY
Thats what I thought by the time I get done reinforcing it I might as well build a round tunnel. I better get going wanted to plant by end of april begining of may.

[dice]

Here is a hoophouse example:

http://westsidegardener.com/howto/hoophouse.html

If you look down at the first picture of the covered
hoophouse, notice the 2x4s on the sides that he
uses to hold down the plastic.

These clips might be handy (stronger than split
polyethelene pipe):

http://www.atozsupply.com/Snap_Clamps_C106.cfm

(That is a chronic problem: wind creating enough stress
on the plastic cover to pop the end clamps off of the
framework. The pvc ones are rumored to hold better
than split pieces of polythelene pipe.)

[bbb123]

Thx dice I'm gona check pvc prices sure I'm gona have a heart attack. Also whats your opinions on 3,4 or 6 mill greenhouse plastic?

[dcarch]

When air flows faster on top, becasue of longer surface area, it will creat up lift force. That's the basic aerodymanic design theory of airplane wings.

Its is therefore also important to consider achoring the hoophouse members to prevent up-lift force.

dcarch

[dice]

Also whats your opinions on 3,4 or 6 mill greenhouse plastic?

Everyone that does this seems to agree on 6-mil. (I guess the
thinner plastics are simply too fragile.) I priced out materials
for a 10'x20' about a year ago at HD. Under $100, and
the single most expensive item was enough 6-mil plastic
to cover it.

Minor tweak: some recommend reinforcing the stub that sticks
up out of the ground with a short piece of rebar pounded
down through it.

[bbb123]

I read that hoop house article again and he is using regular plastic not the greenhouse stuff. I guess its temporary cause I use that stuff on the porches of my poultry buildings for the young birds and I only get a year out of that. Enough light passes through that plastic for stuff to grow? I thought you had to use the greenhouse plastic.

[dice]

Enough light passes through that plastic for stuff to grow?

That likely depends on the exact product. Probably not all 6-mil
plastics have the same translucency. You would get some
difference between one company and another's product, which
does not matter when using them for drop cloths, temporary
rain protection, and other non-greenhouse applications (so
nothing is said about it in the product descriptions).

One could perhaps compare different generic 6-mil plastics
with something like a photographer's light meter, a standard
size box framework to staple the plastic to, and a light
suspended over it in a dark place (so that you always
have the same light and distances to measure how much
light is getting through the plastic).