An environmentally friendly “green” roof is not feasible for the Target Center, a Department of Community Planning and Economic Development (CPED) staff report to the City Council indicated.
The staff report instead recommended a more conventional replacement for the Target Center’s aging rubber membrane roof. The current roof was expected to last 15–20 years when it was installed 18 years ago.
A 2006 report from Kandiyohi Development Partners indicated a green roof system — involving a layer of soil and plantings — would have a longer lifetime than a conventional roof, reduce cooling costs for the sports arena, better manage storm water runoff and even help reduce the urban heat island effect around Downtown. But a follow-up report by architecture and engineering firm Leo A Daly Company concluded a green roof would pose too many problems.
A green roof would be too heavy to also support the “lighting, speakers and other props” used during concerts at the Target Center, the CPED staff report stated. Bringing a green roof down to the desired weight — 13.4 pounds per square foot — would require using less soil than is recommended and increase the need for maintenance.
The CPED report found a conventional roof would do more to improve the acoustic quality of the Target Center. It could also double the insulation value of the current roof, reducing heating and cooling costs.
Replacement of the Target Center roof is on the city’s capital improvements and maintenance list for 2008. Construction is anticipated to begin in April, with completion sometime this summer.
A conventional replacement roof was estimated to cost about $2 million in the CPED report.