After being renovated over two years at a cost of $2.2 million, the University of MinnesotaâÄôs Williamson Hall is still waiting for work on its roof to finish. While work on the rest of the building was finished in August 2008, the roof is protected only by a waterproof cover and Facilities Management officials are deciding between covering the building with rocks, a more traditional solution, or installing a âÄúgreen roofâÄù made of soil and plants. But while officials are considering their options, Greg Williams , an operations supervisor in Facilities Management, said sunlight is degrading the Williamson roof seal and needs to be covered quickly. Williamson is an ideal candidate for a green roof because it was designed to have one when it was built in 1970s, he said. Along with students from EcoWatch , Williams, who is in charge of maintenance at Williamson Hall, is working to bring attention to the issue in hopes of ensuring that a green roof is installed quickly. A green roof is any roof that uses living plant material as part of the buildingâÄôs roofing system, Corrie Zoll , a board member at the Minnesota Green Roofs Council, said. Green roofs are usually composed of native plants and Zoll said they can help decrease heating and cooling costs as well as lowering amounts of storm water runoff from the roof. He said if well designed, a green roof will pay itself off over the course of its lifetime, which is usually two to three times longer than the lifespan of traditional roofs. A green roof at Williamson Hall would cost less than $100,000, Williams said âÄî about 20 percent more than a traditional roof âÄî but Zoll estimated green roofs can cost up to twice as much as traditional roofs depending on the materials used. Some professors and students are researching the viability of a green roof at Williamson Hall, Les Potts , grounds superintendent, said, and a new roof, probably a green one, should be installed by the end of spring or beginning of summer. Potts admitted the project âÄúneeds to be wrapped up,âÄù but said the roofâÄôs waterproof membrane is covered and is not degrading. Williams said parts of it are covered, but there are many exposed spots that he worries are being damaged by sunlight. Although he described himself as a âÄúproponentâÄù of green roofs, Potts questioned whether Williamson, a building that has had issues with leaks in the past, was the right building to try something different and install a green roof. Even though the University has green roofs around campus, not many people know about them and Potts said news that a building with a green roof is leaking could give them a bad reputation, even if theyâÄôre not the source of the leak. âÄúIf weâÄôre going to try and change how people think about it, we should be careful of where we do it so it doesnâÄôt come under question about causing leaks,âÄù he said. Williams said a portion of the $2.2 million in renovations addressed leaking problems at Williamson and there have been no issues since. Roots from WilliamsonâÄôs previous green roof that crept in between the membrane and windows were to blame for some of the buildingâÄôs previous leaking issues, but John Erwin , a horticulture professor currently experimenting with plants on the roof, said leaks relating to the green roof are now âÄúeasily controlled.âÄù Mike Weitekamp, spokesman for EcoWatch , said his group took an interest in green roofs at the beginning of the year, pursuing grants independently before teaming with Williams to get a green roof installed at Williamson. As the campus expands and there is less and less green space, Weitekamp said storm water runoff could become an issue; a problem green roofs could help alleviate. He also said by placing a green roof on Williamson, close to the campus entrance, the University will be showing off its sustainability to all visitors who walk through the front door.