Quote Originally Posted by JeffW
Yes that is a great way to make a hoop house, PVC is cheaper but metal is the way to go and that setup you are looking at is slick it was the best one I have seen for that type of large scale bending. As for poly I am still not sure what I want to go with next time although UV material last longer than cheap plastic you buy at local hardware.

My goal is to use polythene next time I rebuild mine but looks like the pole barn roof get's priority and with a 30x40 it will drain my tax return....oh well.

Looking forward to seeing your hoop barn when you get it going. Big fan of hoop houses around here and they work well....better than glass they say.
I was reading on a WSU site that the reason that PVC doesn't get along with contractor's plastic (or maybe even Polyethelene) is that the PVC "off-gasses" over time, and the gas reacts with the plastic to cause it to deteriorate. She said that you should only use 6 mil UV treated polyethylene which should last for two to three years. I looked up 6 mil polyethelyne, and it is possible to buy it without it being treated, so watch what you buy when you do buy! I'll see if I can find that link .

Ahh, that wasn't so hard, I had that one bookmarked http://cru.cahe.wsu.edu/CEPublicatio...25/eb1825.html
Quote Originally Posted by Carol A. Miles, Ph.D. and Pat Labine, Ph.D.
Polyethylene plastic is available in many grades. A 6 mil weight is recommended for greenhouses. Selecting a lighter weight (4 mil) is not recommended. Untreated polyethylene will cost less initially; however, the lifespan of the material is significantly less, and the material will likely degrade after one year of use. When treated with a UV inhibitor, 6 mil plastic generally is guaranteed for 3 years.

Gases that escape from the PVC (polyvinyl chloride) pipes contribute to the deterioration of the polyethylene plastic. To prevent "off-gasing," paint the PVC pipes with white latex paint.