Jason here, CEO at Edenworks. Roof load is a question we get a lot, and it turns out not to be a dealbreaker if you can distribute weight on the building's col

Jason here, CEO at Edenworks. Roof load is a question we get a lot, and it turns out not to be a dealbreaker if you can distribute weight on the building's columns effectively. Our next greenhouse will be ~ 110 lbs/s.f., which is heavy but nothing a little dunnage can't deal with. On a side note, a research team at Columbia conducted this awesome study showing there's over 5,000 acres of rooftop space feasible for urban farming in NYC (also recommended for any ArcGIS fans): http://urbandesignlab.columbia.edu/files/2015/04/4_urban_agriculture_nyc.pdf http://urbandesignlab.columbia.edu/files/2015/04/4_urban_agr... Regarding grains and legumes, you're right and I wouldn't recommend rooftop aquaponics for it - you simply need too much land. I do believe however that urban aquaponics can play a bigger role in supporting a growing, global middle class, which is consuming more vegetables and protein and is especially sensitive to food safety in some regions.