Rooftop greenhouse growing isn't easy

Sunday, November 3, 2013

The operators of Lufa Farms, on the roof of a commercial building in Montreal, brag that it grows more than 453 kilograms of vegetables every day of the year from its 32,000-square-foot hydroponic greenhouse, with six employees producing 40 types of vegetables and herbs. Customers get boxes that are delivered to pickup points. A small box costs $22; a bigger box, $46.

But it's not as easy as it looks, according to The Globe and Mail. Rooftops make up 30 per cent of the space in major cities, but only 10 per cent of commercial rooftops are strong enough to support a greenhouse, according to Aaron Quesnel, founder of Sky Harvest Inc., a startup in Vancouver that hopes to do the same thing. Some buildings can't be economically retrofitted, and others are already at legal height restrictions and can't take a greenhouse on top. (The Lufa Greenhouse is 4.2 metres high.)

The Lufa greenhouse, built in 2011, is 80 metres by 43 metres and weighs 1.8 kilograms per square foot. The load capacity of the building that supports it is 45 kilograms per square foot. Modifications included two staircases from the floor below, a small freight elevator, a water supply and irrigation pipes. There are about 3,000 plants in the greenhouse.

Lufa's operators plan to expand to two more locations, in Montreal and in adjacent Laval.