Urban Agriculture is gaining momentum in Seattle. As farms are introduced within city limits, prototypes for urban rooftop food production are springing up on new construction projects. Whether for personal plots, community gardens, or small-scale commercials farms, the message is the same: rooftop farms make productive use of underutilized urban space, support the local food movement, decrease food miles, and introduce new streams of revenue to the local economy. Like other occupied roof decks, they provide an active amenity to building tenants, and bring eco-system services such as mitigating urban heat island effect and managing stormwater.
With existing buildings, the constraints are often structural. Flat roofs are rarely designed to carry the load of wet soil and stacked produce. However, existing buildings going through a major retrofit provide an opportunity, making new square footage available. This project – a retrofit of an existing building with a limited-capacity mild concrete slab – attempts to overcome the odds to provide a productive farm in the heart of the city. Where concrete columns support the slab at dropped capitals, the capacity is for all intents and purposes unlimited. This nuance of the existing structure presents an opportunity.
This solution proposes a steel frame touching down at the roof surface directly over existing concrete columns below. Lightweight panels are attached to the frame to create a surface for planters, arranging in aisles for grower access.