Farming on Rooftops - What the Future Looks Like?

[weinoo]

This past March, a friend and I led an IACP tour group, where we got to see first hand a rooftop "garden" in Queens, NY. It was followed by dinner at Roberta's, in Bushwick, where gardening is also part of their claim to fame.

Yesterday's NY Times ran a nice article about rooftop farming, including a profile of the place we visited, Brooklyn Grange. Now don't call it a garden, because the rooftop we toured in Queens actually was an acre large...not your typical backyard.

In addition to supplying residents and restaurants with locally grown produce, these urban farms are also supplying places such as Whole Foods. I personally have bought greens from Gotham Greens (based in Greenpoint) at Whole Foods; I'm sure others have as well (otherwise they probably wouldn't be stocking them).

Other than the obvious locally grown produce, these rooftop farms provide certain ancillary benefits. As the article points out:

For city officials, the rise of commercial agriculture has ancillary benefits, as well. Rooftop farms have the potential to capture millions of gallons of storm water and divert it from the sewer system, which can overflow when it rains. And harvesting produce in the boroughs means fewer trucks on local roadways and lower greenhouse gas emissions,

a goal of Mayor Michael R. Bloomberg’s administration.

So, looking at all the benefits, as well as few downsides, is this the future of agriculture? What do you think?

[heidih]

I don't think it is the future of "agriculture". I think it is a wonderful idea and hope that it spreads. Urban gardening has been on the rise with the people utilizing whatever space they have including front yards to grow edibles. Member KennethT showed us his NYC indoor gardening set up recently here.

[KennethT]

I've done quite a bit of research on this topic. At one point, I had a fantasy of turning the roof of my workplace in Yonkers (just north of the Bronx in NYC) and turning it into a hydroponic greenhouse focusing on high quality produce for restaurants. A lot of the stuff I was/am growing in my living room was a test bed for a potentially larger project. I also don't think it's the "future of agriculture" just yet. In theory, it's great, but the reality is the cost. It's VERY expensive to set up a decent sized greenhouse, which will then have to be amortized over how much produce you think you can sell. A plus of the hydro greenhouse is plant density and number of crop cycles per year. Even still, you need to get a very high price for your crop to amortize the greenhouse. There are more expenses than jsut the setup though - at least in the Northeast, during the winter you need to provide heat and supplemental light. Lighting is really expensive - especially in this area where our power rates are not so friendly. In the summer, you have to cool the greenhouse, which is also expensive. Then labor, of course.... And with hydro (as with all farming) you have nutrient cost, which is actually a lot less with hydro than traditional soil based farming and probably the least expensive part of the whole thing.

An interesting read is: This work by Dickson Despommier

[annabelle]

Is this a safe practice structurally? I've been the victim of a collapsed roof from too much accumulated rainwater before.

[KennethT]

It depends on the roof, I guess. Here in the northeast, buildings are designed to handle at least 2 foot heavy snow loads which adds up to a lot of weight. I have some structural engineering experience, and a quick back of the envelope calculation told me that my roof would definitely hold the weight of a hydro greenhouse. Keep in mind that a hydro greenhouse is much lighter than a standard soil based greenhouse because soil is very heavy, especially when saturated with water. Also, hydro farms require about 30% of the water required for a standard farm, and there is no fertilizer run-off that is bad for the environment.

[annabelle]

Thanks. I was thinking of people who decide to start a garden with potting soil on their rooftop. It wouldn't be a problem if it were a small garden, but covering the whole roof? I'd think the city would get involved.

[dcarch]

Is this a safe practice structurally? I've been the victim of a collapsed roof from too much accumulated rainwater before.

No. I don't think it is Code compliant. A roof is designed based on some establish weights and environmental assumptions. The Code never included requirement for a farm.

I don’t think structural engineers would be willing to put themselves at risk by signing off structural load above the Code’s standards.

You will need to get Landlord’s agreement.

Who will be responsible for a leaky roof? Most roofs do leak.

You will need to get insurance company’s agreement.

Roof top may have difficulties meeting fire exits for the worker.

Where do the workers go to the bathroom?

New buildings can be designed to accommodate a roof farm, but the additional structural load is cumulative, in other words, every structural column all the way down to the foundation will need to be strengthened for the roof load. That is a lot of added cost to a building.

I don’t think there are many existing buildings with elevators going to the roof. It is a lot of work not having an elevator to operate a farm.

If I am in an apartment building, I don’t want to be in the same elevator with produce, fertilizers, etc. being transported.

Plumbing for a taller building will need water pumps because water pressure may not be high enough.

If I were the owner of the building, I would not allow a farm to use the drain system of the building. All kinds of stuff can easily clog up the drains.

Who is to inspect if everything for a farm is anchored properly in case of high wind?

I think a small roof top farm will increase urban traffic.

Just my humble opinion.

dcarch

[ScottyBoy]

One of the reasons I moved into my new place was the roof. 1600sq/ft that I'm building out for my new garden over here.

[annabelle]

dcarch, thanks for stating the particulars. Those were my concerns, as well.

[KennethT]

dcarch has it nailed down pretty good... what happens with a rooftop farm (a commercial one at least) is that you need to get permits to do anything. Before you can get permits, you need an engineer to assess the situation and make sure that it will be safe for the roof and also any possible wind loads that might blow anything off the roof and injure someone below. What happens when a non-commercial enterprise decides to plant their roof? That's the main concern.

ScottyBoy - that is my concern for you! I applaud your decision to get a new place because of the roof potential. I just hope your roof can handle 1600 sqft of dirt!! I'm not that up on soil stats, but it seems like a bag of topsoil weighs about 50 pounds, right? How much does that cover? Maybe 1-1.5 cubic feet? (1-1.5 feet long, 1 foot wide, 1 foot deep). With a 1 foot soil depth, a 1600 sqft roof would use about 1066 bags of soil to completely cover (at the rate of 1.5 cubic feet per bag) or about 53000 pounds! And when it rains, it'll gain all that water, so it'll be much heavier than that!