Question
I'm interested in installing a patch of grass on a roof deck. I don't know much about this stuff, but I assume that I could use a plastic tray that drains, and add layers of various material on top of which I could add sod (e.g. gravel, sand, soil, then sod). Questions: 1) Is this a dumb idea? 2) If not, what are the layers that would be needed to grow and maintain healthy grass?

Thank you!
Jason

Answer
Hi Jason, Not a dumb idea, but a few things to consider...
The size.  Will your deck support the weight when it's wet?  
Watering.  Can water get under your liner and keep the wood wet causing decay?
You best soil will be your own garden soil. No need for gravel, gravity will help your drainage and with air exposure on both sides, it could dry very often. Jim