Target Center Can’t Support Green Roof, Report Concludes

First Kanye cancels, now more disappointing news for Target Center: an architecture and engineering firm has concluded a green roof isn’t feasible on the arena.

The Target Center’s roof is close to two decades old, and the City Council had been discussing the possibility of replacing it with a green roof. Several cities are using green roofs as a way to add parks and green space to already crowded and developed urban cores. They usually consist of a waterproof membrane topped by a layer of lightweight planting material.

A new report to the city from Leo A. Daly Company, however, says Target Center can’t support the weight of a green roof along with all the lighting, speakers and other props that need to be hung from the ceiling during concerts and other events.The arena’s current roof weighs about 13.4 pounds per square foot. The lightest green-roof system the consultants could identify weighs about 17.1 pounds per square foot. The report also notes that the arena’s management hopes to improve acoustics by installing a sound absorption system to the ceiling, which would add more weight to the roof.

The City Council’s Health, Energy and Environment Committee is scheduled to discuss the report at its meeting on Monday, Dec. 10. Replacing the roof is still on the city’s project list. Work on a new conventional rooftop is expected to begin around April 2008 and cost around $2 million.

Minneapolis hosted an international green rooftops conference in May. The city’s skyline boasts several examples including gardens atop Brit’s Pub, the Central Library and the Northstar Crown Plaza. Besides adding some green to otherwise concrete-gray downtowns, green roofs help manage stormwater runoff and reduce the “heat-island effect” on hot summer days.