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october 2013
guest feature article

Kentucky Green: Vegetative Roofing in Downtown Louisville

 

By Reed Hitchcock
Executive Vice-President, Asphalt Roofing Manufacturers Association (ARMA)

10/14/13

White or Green?

The iconic American Life & Accident Insurance Company building in downtown Louisville, Kentucky originally gained notoriety for being the last notable work of the famous German architect Ludwig Mies van der Rohe.  However, this impressive building still had room for improvement.  Recently, the landmark site was able to increase its sustainability and prominence in the area by installing the largest privately-owned vegetative roofing system in Kentucky.

The American Life & Accident Insurance Company greenroof;
Photo Courtesy of ARMA.

Planning for the new roof began back in 2009 when it became clear that the existing 20-year old roof was no longer in good-enough working condition to protect the structure.  The original re-roofing plan called for a 2-ply modified bitumen roofing system with a white, reflective cool roof coating on top.

This type of sustainable roofing option was eventually decided against because of “neighborly” reasons.  The American Life & Accident Insurance Company building is six-stories high, and surrounded by many taller office buildings.  The concern was that the roof would have been too reflective, potentially making it unsightly for the people in the higher stories of those surrounding buildings, according to Ed Umbreit of Johns Manville, a leading manufacturer and marketer of premium-quality roofing products, who worked on the project.

The newly finished American Life & Accident Insurance Company greenroof;
Photo Courtesy of Green Roof Solutions.

With input from the asphalt membrane manufacturer and American Roofing & Metal, a premier commercial, industrial and residential roofing contractor, the owner decided to take a slightly different direction on the project.  A modified bitumen system, upped to 3-ply for added redundancy and protection, would still be the roofing system of choice.  However, instead of adding a reflective roof coating on top, they would install a sustainable vegetative roof instead.

Vegetative Roofing & Modified Bitumen: A Perfect Team

The reason they decided to stay with a modified bitumen system after the change to a vegetative roofing system, Umbreit said, was that, “There is no better alternative to 3-ply modified bitumen.  The redundancy of the plies, the durability of asphalt and the superior modified bitumen blends that were available make it the best choice for this kind of vegetative roof.”

The American Life & Accident Insurance Company greenroof a couple of years after installation; Photo Courtesy of Sempergreen.

The vegetation used for the roof was primarily sedum blankets provided by vegetative roofing products company Sempergreen.  Each blanket was made up of ten to twelve different species of Sedum.  Biodegradable and grown on a coconut fibre carrier, laying out the blankets did not prove to be a problem for the team.

In total, more than 12,900 square feet of the blankets were used for the installation.  They were installed over approximately 5 inches of growing media, according to Boyd.  Sedum plants are capable of storing water which helps deal with runoff water from the building and lessens the need for constant upkeep.

This is the first vegetative roof of this size that the project teams had worked on and they turned to the materials they knew they could trust best to support and contain the vegetative roofing.

“The main purpose for using a modified bitumen system is that it provides exceptional waterproofing,” said Joe Boyd, commercial sales manager at American Roofing & Metal.  “Any soil, plant life or water that starts to overflow gets stopped by the roofing system.  Also, since everything is on top of the roof and the modified bitumen is the base layer, it keeps the building dry by using a tapered insulation system for positive drainage.”

 During construction, pre-vegetation; Photo Courtesy of Green Roof Solutions.

As this was a re-roofing project, the existing roof material was removed all the way down to the concrete deck.  From there, the roof was built back up and includes a stainless steel leak detection system which can pinpoint leaks to almost exactly where they began.  The 3-plies of styrene butadiene styrene (SBS) modified bitumen and an irrigation and drainage system to supply water and remove runoff from the soil and plant life would then be installed.  SBS-modified bitumen membranes resist water penetration, which makes this particular type of roofing system especially well-suited for a vegetative roofing project.

Distributing the growing media; Photo Courtesy of Green Roof Solutions.

"Johns Manville, Green Roof Solutions and American Roofing & Metal worked together to provide a complete green roof system for the American Life Building," added Brian Barry of Green Roof Solutions, which provides high quality green roof, roof garden, and living wall components with a focus on manufacturing and distributing components made in the U.S.

Spreading the growing media; Photo Courtesy of Green Roof Solutions.

Green Roof Solutions worked with American Roofing and Metal to help their team understand the installation and logistics that are unique to this particular green roof assembly.  Barry elaborated, "The green roof included a protection layer, root protection, drainage layer, separation fabric, edge restraints, engineered media, a blended sedum pre-vegetated mat (for instant green) and inspection chambers over the roof drains to allow access."

Installing the Sempergreen pre-vegetated Sedum mats; Photo Courtesy of ARMA.

Green Roof Solutions had personnel on site for five days to make sure that any questions regarding the installation were addressed in a timely manner and maximize efficiency making this a win-win project for everyone, according to Barry.

The installation lasted throughout the summer of 2009, but it did not come without some challenges.  The building’s mechanical room is located on the upper floor.  With all the air conditioning units running, it created negative pressure because of all the air being sucked into the systems.  So, the corners of the building were blocked off with extra membrane, which aided in the application of the system by preventing the flames of the torches used for application from being sucked down into the building.

Close up of the grown-in greenroof; Photo Courtesy of Sempergreen.

Because the American Life & Accident Insurance Company building is located in a downtown area surrounded by an active waterfront park that is home to various summertime events, the contractors needed to install a chute to get rid of trash.  Someone was kept on the ground at all times to monitor for debris and secure the area for safety purposes.

When the 16,385-square-foot-roof installation was completed, the project was delivered on time and under budget, according to Umbreit.

The Results

The building’s vegetative roof system earned the contractor a Bronze award in the Asphalt Roofing Manufacturers Association’s (ARMA) 2013 Quality Asphalt Roofing Case-study (QARC) Awards program.  Now in its 4th year, the national program recognizes the best in asphalt roofing.  The American Life & Accident Insurance Company was honored for its progressive use of a modified bitumen system that provided excellent waterproofing and reliable protection for the both building and the vegetative roofing system.

In addition to the pre-vegetated Sedum mats, three 12-foot-square test beds were installed by Bernheim Arboretum and Research Forest to trial various plant species for the Kentucky climate:

Modelled after a rock garden, this plot includes snow-in-summer and ice plant.
Photo by Hill-Wiche in Fotki.

While the project has gained national attention, it is most often recognized by the occupants of the penthouse apartment on top of the building.  A walkway with pavers was added so that the guests in that residence could view the beautiful aesthetics of the vegetative roofing up close.

The test plot in the foreground  emulates a Kentucky cedar glade, with gray goldenrod
and prickly pear; the area in the background has different types of grasses.
Photo by Hill-Wiche in Fotki.

The durable attributes of asphalt roofing also made it a perfect complement to the vegetative roofing.  While this type of green roofing is very aesthetically pleasing, the main reason to utilize such a system is for the sustainable benefits it brings.

Side view. Photo by Hill-Wiche in Fotki.

“Vegetative roofing is one of the most effectively ‘green’ roofing options available,” said Boyd.  “It does a great job of catching runoff water, which makes it a great addition to any storm water plan.  Also, in cities where heat island effects are a problem, vegetative roofs often help because the vegetation will absorb heat instead of letting it come off the roof.”

Boyd added that this vegetated roof is easy to care for and maintain.  “The only maintenance required is the occasional weeding, fertilizer and watering, which is not much more maintenance than a standard roof.”

A view of all three Bernheim Arboretum and Research Forest test plots.
Photo by Hill-Wiche in Fotki.

Due to its specific function, Bernheim Arboretum and Research Forest provides monthly monitoring and maintenance to the three test plots on the American Life & Accident Insurance Company greenroof.

The American Life & Accident Insurance Company greenroof;
Photo Courtesy of Green Roof Solutions.

For property owners interested in increasing the environmental-friendliness of their buildings, and also adding some beauty to their surroundings, vegetative roofing is a great option.
 

Reed Hitchcock

Publisher's Note:  See the American Life & Accident Insurance Company project profile in The Greenroof & Greenwall Projects Database.  Learn about the following companies in The Greenroof & Greenwall Directory: Green Roof Solutions and Sempergreen.


Reed Hitchcock, Executive Vice-President, Asphalt Roofing Manufacturers Association (ARMA)

Reed Hitchcock

Reed Hitchcock is the Executive Vice-President of the Asphalt Roofing Manufacturers Association (ARMA).  Hitchcock joined ARMA in 2003 and has served in his current role since 2007.  He has led and participated in numerous roofing industry initiatives and coalitions specific to environmental, health and safety matters. For more information on vegetative and asphalt roofing, visit www.asphaltroofing.org.

Contact Reed Hitchcock:
info@asphaltroofing.org or 202.591.2450.


The opinions expressed by our Guest Feature writers and editors may not necessarily reflect the beliefs of Greenroofs.com, and are offered to our readers to simply present individual views and experiences and open a dialogue of further discussion, debate and research.  Enjoy, and if you have a particular comment, please contact the author or send us an email to:  comments@greenroofs.com.

 

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