First, that is a very interesting design. Second, I have a couple quick questions.

Are there squirrels? (Mind you, my squirrel ate everything *but* the food plants...)

Are there community gardens around, that you could get a plot in? No offense but it would probably be easier. (Mind you, often there is a waiting list.)

And, is there a way to run a long hose out your window to the roof? Or would that upset the landlord (if any)? I don't know that I see any issues, but otoh, water and wood don't always mix. I don't know about a wood box. I wonder if there are gravity issues with running a hose to a roof?

When you get farther along, there are people who say that a red fabric under tomatoes makes them grow better.

Very cool though!! It sounds fun!

Thanks for the feedback Need2SeeGreen!

Squirrels -- not sure. It's on a roof so it seems pretty hard to access but I know those guys are crafty.

Community gardens -- yeah I think the waiting list is years, and I don't know that there are any particularly close.

Long hose -- I was thinking of that... You might be right about gravity issues, but I live on the top (3rd) floor and pressure is fine so I expect it would be ok.

Landlord -- is me! It's a condo, I have exclusive rooftop access.

Water and wood -- from what I've read, pressure treated wood is quite water tolerant. Seems the ultra-organic types have some concerns about chemicals leaching from pressure-treated wood into the soil/plants/fruit, but some years ago (2003?) they changed the process to be more food-safe.

Jeremy.

How much is your setup going to weigh, and how much weight can your roof take? What is your roof made of currently, do you know if it's up to snuff to have setup like that on it? What are the average temps on your roof- as in get a thermometer up there and monitor the temps to see how much it aligns or not with the ambient air temp- roofs can get kind of hot sometimes :)

Interesting setup notion though.

awkward to access (ladder through trapdoor), esp when transporting materials, including water

This is a critical consideration, one of the most important aspects of food garden location is that it be convenient. Because of the frequency with which it will be visited.

And in the case of tomato plants specifically, how many tomatoes (the fruits) do you really need? If you haven't done it before you may find later your existing tiny seeming production area is actually perfectly adequate.

You know, I was just looking at a different post discussing drainage, and, is your setup in the lowest part of your roof? From the pic, it looks like it. So, did you already figure out if your roof drainage is already working well? Bc it would be a shame if the toms ended up with wet feet. Have you lived there a long time? I don't know if I'd put it all in the middle like that, per the weight issue beesneeds mentioned above.

Also, is there a parkway that nobody's using? what about neighbors on your street? - believe it or not, sometimes people don't mind if others garden their lot ... esp for a cut of the produce. Esp with the virus, more and more I look at ground and think, some food could be growing in that.

I hate to be a Debbie downer but I think problems will come your way.

Does your condo have an association and rules? You may have exclusive access to the roof but building a structure of any type may not fly. Lets say they let you build it.

Now you have building codes to deal with, and the snow load and live load of the roof will need to be known. The snow loads in Canada are 50 or 60 pounds per square foot. Roof live loads are low at around 20 Lbs/sq/ft and may not of been built to carry and heavy live load, so you'll need to find the live load of the roof and an engineer to certify it will be safe.

One square foot of your planter will weigh approximately 60 + lbs per square foot, or in excess of 960 lbs on 16 sq. ft. This will dead load only and snow load can't be used to determine safety, snow load is for snow load only.

Anyway good luck, and 16" apart will work if they're smaller plants. Farmers plant processing (bush) tomato plants in their fields spaced 18" apart.