Roof Top Gardening
I have a recycled composite (plastic) substrate deck that floats above a rubber membrane flat roof with 4 drain scuppers. one in each corner. this is all new construction and exceedingly heavy duty, due to inner city codes and such.
i want to build a giant brick retaining wall 3'8" high by some 4' wide, that runs 22' across, and fill it with dirt and such for trees. i'm sure that weight on the deck and therefor roof, is not a problem.
my question is: other than a Fabric Filtering cloth of some kind to keep particulates and tiny roots from invading the space below the decking, what else do you think that i'll need?
maybe a layer of Styrofoam peanuts for 'wet feet' problems. but i can't think of anything else.