pvc greenhouses...

I'm sure some folks on here have used PVC to construct greenhouses before. I've researched and learned alot about them, as far as painting the pvc to gain life, using shielding to keep the chlorine from hurting the plastic, etc... also, on the TOP bend of the greenhouse, some burningman lessons are to run the smaller diameter pvc through a larger diameter PVC to give it a little more structure... anyhow, all that is a mute point if the PVC will become too brittle after one or two seasons... If I can squeeze the same longevity out of the frame that the poly provides that would be ideal.

I have ONE specific question and have not been able to find an answer yet... Longevity? those that have built one, how long was the PVC viable for until it became too brittle to keep the structure intact?

We are building several HUGE greenhouses here for various operations, but I would like to get one in this winter just so we can start our garden crops early before transplanting them, however I don't want to build something that will go all to heck in a year and not be usable the next year. So, my question to those who have built them or know people who have, how long have they been standing?

**edited to add***
I will be using "real" greenhouse poly, the extra expense really isn't a big deal for it if the PVC will hold up for a few seasons...

Around here (similar UV exposure as most of NC) people get 3-6 years out of a frame used year-round, 5-10 if it is covered in heavy shade cloth all summer. Basically 1 good poly lifespan or 2 cheap covers. That is if there is now snow load to speak of. Grey PVC electrical conduit gets more life due to the UV stabilizers, but not as much as you would hope--it may last an extra year.

I think the metal EMT conduit hoops are a much better idea. http://www.lostcreek.net/

Or you can bend your own Gothic hoops using a standard conduit bender and 3/4 conduit.

thanks Rscott, after seeing alot of your posts, I place stock in what you say. For our big ones we're definitely going galvanized metal, I'm still on the fence of whether or not to bend it ourselves or buy a kit but I'll probably just get a decent pipe bender/expander kit and order a truck load of pipe.

our snow load is generally pretty low, we have some doozies but on an average year we get 3-5 snows of 3-6 inches tops and those rarely last more than a day or two. I may go on and design quick attach pillars that I can pop under the bows if we do get a good snow though.

I was actually leaning more towards a gothic arch, it would seem to have more usable space with the straight walls than a hoop structure and would be easy to do with available connectors.

Thanks for the info, that's what I was hoping to hear, I don't plan on this one being there for long, we will be doing a solid built greenhouse for our personal garden starts and my gal's tropicals (shes filipina), but this should get us by for a few seasons then.

I'm usually of the type to do something right and do it good the first time around as it does save money in the long run, but I have promised a greenhouse by spring and we have quite a few other projects to do this winter so I am spread pretty thin financially haha. This one should keep the mrs. happy for a season or two though I'll post pics of the project going up!

Looks like I have space for a 12x36 in the area that we had set aside for it I'd start on it tomorrow if it weren't for our new road going in right beside it, gotta get that done first so the equipment doesn't kick and tree branches over and mess it up haha. I'm thinking pressure treated knee walls to put the hoops or arches on top of so I have a solid structure to frame the openings to, and hopefully those will last long enough to be re-used when we go back with real metal arches...

I've even got a spare outdoor wood furnace i can heat the critter with