Tremco Roofing and Building Maintenance and Xero Flor America LLC (XFA) announced the completion of a green roof at Providence St. Mary Medical Center in Walla Walla, Wash. The Tremco Roofing Sedum Mat System, with components supplied by XFA, was installed on a 10,000-square-foot section over the Operating Suites on the Medical Center’s new 16,000-square-foot structural roof.

“Providence St. Mary Medical Center needed to replace this roof and researched the benefits of adding a vegetated roof. This roof replacement approach doubled the life of the new roof membrane and provided other benefits as well,” St. Mary Director of Facilities Larry Baer said. “Air temperature reduction in the summer months, sustainable management of stormwater and an enhanced patient experience all contributed to our decision to install a green roof.”

“The green roof will help the hospital meet its sustainability goals by conserving energy,” Tremco Sustainable Roofing Specialist Elizabeth Hart said. “Moderating temperatures on the roof and lowering the temperature of the air drawn into the rooftop HVAC units decreases energy use and utility costs.”

In selecting a green roof system for the project, St. Mary and its architect, Mahlum Architects of Portland, Ore., considered immediate visual impact, ease of installation and low maintenance. The Family Birthing Center and the west side of the Intensive Care Unit look out on the green roof. Thus, an instant green roof featuring extensive vegetative coverage with mature, full-grown plants for immediate beauty was a priority. In consideration of patient privacy concerns, a green roof that could be installed quickly and require minimal maintenance was also preferable. To reduce any potential for disrupting patient care, Enviroscapes Northwest Inc. of Portland, Ore., the green-roof installer for the project, worked only in limited, designated hours.

“We utilize Xero Flor pre-vegetated mat technology, because it has a 40-year track record of successful applications on green roofs worldwide,” Hart said. “Their vegetated mats are the only ones Cradle to Cradle (C2C) certified for environmental sustainability.”

“The pre-vegetative mats are grown for a full nine to 12 months on independent, local farms, so the plants are mature and adapted to the regional climates where they are installed. Using local horticultural suppliers supports local economies, reduces the costs of shipping, and decreases the carbon footprint,” XFA General Manager and Technical Director Clayton Rugh, Ph.D., said. “And all the components for U.S. projects are 100-percent manufactured in the United States.”

For more information, visit