Root Cellar

Specs: 4,500ft of green roof divided into 6 separate sections installed in 2006/2007

The Root Cellar is an excellent example of a low cost, minimal input green roof. The Root Cellar was a cooperative project between the center and Penn State’s Office of the Physical Plant and is used to demonstrate the potential for lower cost construction in addition to its use as an open-air classroom and laboratory for students and faculty working on green roofs.

The root cellar is an old farm building built in the 1920’s and re-roofed with an extensive green roof in 2006 and 2007. It is currently used for storage and to house the Cellar Market, where produce from the Horticulture Farm is sold every Wednesday afternoon during the summer. The new green roof is approximately 4,500 square feet and is divided into six equal sections. Runoff from each section drains through a series of drainage pipes into the back of the building where a flow monitoring system is being installed. Four of the roof sections were covered with four inches of a simple roof media, formulated from local gravel and compost from the University Compost Project. The other two sections were covered with eight inches of the same media. Students from the green roof technologies class produced all of the plants and planted most of the roof in the spring of 2007. Many of the plants are typical green roof plants but some are new untested species and cultivars. The plant community on the roof will be followed over time and new plants will be added to continue the process of selecting and evaluating plants for use on green roofs.

The roof and media were installed in the Fall of 2006 and the roof was planted by students in Horticulture 497 “Eco-roof technology” in the spring of 2007. The roof will be used for runoff monitoring and vegetation evaluation. The project is a collaboration between the Penn State Office of Physical Plant (OPP) and the Center for Green Roof Research. It was done in such a way as to demonstrate the possibilities for low cost green roofing on campus, using local materials (gravel and campus compost) and a local contractor for design and construction (Stone Valley). The total cost for this roof was approximately $7 per square foot.