I know I could have (should have?) asked this question in the Gardening forum, but I'll get more answers here. How long can pvc pipe be expected to last as the framework of a greenhouse? 5yrs? 15yrs? 50yrs? I know that it has a limited lifetime due to ultraviolet radiation. I'm just trying to determine if the initial savings in using pvc would outweigh the long life of a metal framework.