Yup, I see lots of problems with this idea, sweetie. Is there a reason you don't want to use pots? I wouldn't bother trying to make a 'roof top garden' on a small balcony. Just get a collection of great pots (all tied together by material, color, shape to not distract from your plants) with drainage holes, get wider than tall. You can use tall, narrow pots turned upside down to support and raise some pots to make more use of the vertical dimension. So much can be grown in pots successfully. Don't forget hanging baskets making even more use of your area in 3D. You HAVE to use bagged sterilized potting soil!! You need drainage holes. A way to lift the bottom of the pots off of the surface they sit upon. I'd even purchase bottled water if I had treated city water out of the tap. No rocks no gravel beneath the soil and above the drainage hole. What is your zone? What is your orientation to the sun? Are you on the north side of the building or south for instance. What is the usual direction for wind? If you've got a winter, you will have to drag all of those pots inside, or you'll not get the perennials back in the spring. If you asked your management for the building, your association you'd probably get a big NO WAY. But pots are different, they are movable. There are ways to protect plants in pots for the winter. And when moving all plants indoors for the winter, you have to do it slowly, not all at once. To get the plant used to the environment indoors, they have to be taken inside for a couple of hours and then back outside. This continues increasing the time spent inside for a few weeks before your plants are ready to live through the winter indoors. Same thing in the spring to harden them back to living outdoors. How big is this balcony? I've done Landscape designs for decks, balconies with pots big enough for trees, water walls, lots of other smaller pots to tie all together. People were part of the design, to be able to sit among the plants, water sounds and grasses, trees that sway in the wind. Never was there any idea to making the surface of the balcony mimic the normal garden surface. Not a good idea. All that work and expense could be focused on pots, soil, automatic watering systems, an indoor winter area, wheels on the bigger heavier plants and christmas lights and burlap to wrap the trees and their pots to survive the winter. Oh, you could also get water filters for your tap water to get rid of the crap they put in your water and that would also be very good for you as well. There are those skinny coiled hoses to screw onto your faucet (make sure you can do this or you'll be purchasing a new faucet)...they are easy to use and pop back into a coil. Beneath the pots should be air space (lift with pot feet or tiles) then some sort of a tray to collect excess water and then use a tiny hose to siphon it away from the balcony beneath and the architecture. You don't want to piss off your neighbors beneath or cause water streaks on your building.