Subscribe
Lessons from green roofs at St. Paul and Elk River schools
Folks in Elk River and St. Paul now have green plants up in the sky. That’s because Elk River’s Twin Lakes Elementary School, and Community of Peace (CPA), a St. Paul chartered public school, have installed “green roofs.” Everything I read urges communities to adopt this idea.
Beth Pearson, a Research Specialist at the University of Wisconsin/Milwaukee Great Lakes Water Institute says that green roofs provide “immediate benefits to the environment, both inside and outside a building.” That’s because they help conserve energy inside a building, and help generate valuable oxygen outside.
The green roof at Community of Peace is open, and hosted students, faculty, St. Paul mayor Chris Coleman, and other elected officials last week. Kong Khang, 18, CPA student council president, explained in a speech that he had asked students how they felt about the green roof. One student urged that the school start a gardening club. Khang smiled “Man, this person stole my idea!” He also mentioned “Some students can’t wait until spring comes so they could see the flowers.” There are 50,000 plants (right, 50,000) on the roof.”
Community of Peace, a 13-year-old charter public school enrolls a diverse group of 640 students, gradesK-12, plus 30 pre-kindergarten students. The U.S. Department of Education and Center for Education Reform have recognized CPA as one of the nation’s outstanding charter public schools. The school has been cited for programs that teach character and “peace-making” – and the ability to get along with others.
Principal and founder Dr. Karen Rusthoven sees the new roof as “one more step toward our goals of helping students achieve their potential, and being a constructive positive force in St. Paul.”
Dan Collins, principal at Twin Lakes says that helping to design the school was “a once in a lifetime opportunity.” The school includes several features designed to save energy and enhance learning. Mike Schrock, A.I.A, and lead architect for the building described “light tubes” that bring natural light into the building, thus saving on electricity costs. Collins agrees: Twin Lakes has “a huge amount of natural light.”
Deb Rathman, Lead architect at CPA believes green roofs are “a great option for schools. Schrock agrees, “The environmental benefits mean we’ll see a lot more of these. Flat roofs make sense for many schools, Adding plants on them reduces the energy needed to heat and cool buildings.” Come spring, sedum flowers in many colors will open.
Twin Lakes’ green roof is nearing completing. Tom Walerius, Elk River Assistant Superintendent, noted there are a few details to be worked out before students can visit the roof. One issue is handicapped accessibility. Schrock ‘s design included rubber pavers, allowing wheel chair bound students to move on the roof. But pebble paths were installed. “We’re talking with the contractor about this,” he says.
Beyond the green roofs, these two schools illustrate something else. There is so much to be learned from innovative, effective district and chartered public schools. We must get better at spreading what the most talented educators have created.
Comments
Considering the life span of
Considering the life span of a normal school roof, and even allowing for use of an additional moisture barrier, one can only wonder how will these schools will facilitate repairs when these roofs leak or what they will do if a drain clogs?
It’s often very difficult to locate and repair a leak on a normal roof and often our roofers will struggle to locate and repair an elusive leak for months, if not years. Water pooling is a problem on any roof, especially if it does not have adequate drains or the drains are not functioning properly. When you add soil and a plant material to the equation you come up with a nightmare finding a leak. Then, we have to ask what the schools will do when it is time to replace the roofs, that normally have a life of about 20 years, assuming these gardens were installed on new roofs.
life span of green roofs
In response to the comment about the lifespan of these green roofs and finding leaks I would point out a few things
- The life span of a professionally installed green roof should be much longer than a traditional roof for the simple reason that the waterproof membrane is better protected from the elements and in particular the extremes in temp that wear on the membrane of a traditional roof.
-Assuming the schools had the roof installed by certified contractors the membrane and the work should also be warrantied for the same or longer period of time as a traditional roof.
- If the roof does eventually leak a competent contractor should be able to locate the leak and repair it without a lot of additional expense – a green roof doesn’t mean there is a couple feet of soil on the roof – these roofs generally use only several inches of specially engineered growth media (i.e. expanded shale) that allow for proper drainage and are moved for repairs without a major effort.
Considering the life span of (Reply)
Replying to:
Submitted by Anonymous (not verified) on Sat, 10/27/2007 - 03:06.
Best practice for green roofs is to install a fully adhered waterproofing membrane on the roof deck and not a roofing membrane. An additional "moisture barrier" as anonymous refers to is ambiguous.
The waterproofing membrane in a green roof application is actually less vulnerable to in-service damage than many types of roofing membrane assemblies exactly because of the green roof protecting the membrane.
Leak detection and repair does involves greater work effort than in a conventional roofing application. Best practice engineering with qualified, experienced installers can reduce the occurences of leaks and associated repair costs on all types of roofing applications.
The waterproofing membrane with the protection of the green roof over it can provide a life span considerably greater than 20 years and thereby reduce the annualized cost of replacement.
leaks and green roofs
The idea of covering a roof with plants does seem counterintuitive, given the importance of proper roof maintenance. Most commercial green roofs, though, are “inverted”: the membrane is applied directly to the roof deck, with the insulation above. That largely eliminates the voids under the membrane (through which water can travel horizontally) so if you see evidence of a leak inside the building, you can say with some certainty that the leak is directly above. If leaks are a particular concern, relatively inexpensive Electric Field Vector Mapping (EFVP) systems can pinpoint leaks to within a couple of inches, without moving or even disturbing the green roof itself.
More importantly, though, leaks are much less common on green roofs. As a rule of thumb, the membrane under a green roof will last twice as long as a conventional roofing membrane – or even longer. The layers of the green roof protect the membrane from degradation from thermal swings and UV radiation, the primary causes of roof failure over time. There are green roofs in Germany that are fifty years old and still going strong.
Green roofs are not foolproof, nor are they appropriate for every building. Like any building system, they must be carefully considered and well-detailed, but the environmental benefits (stormwater treatment, energy and resource conservation, urban heat island mitigation, habitat restoration, not to mention beautification) are broad and quantifiable. If you have any questions about green roofs, please feel free to contact me via email at cwegscheid[at]cermakrhoades.com.
Leaks are less likely and easier to find in green roofs
It is my understanding that green roofs leak much less than traditional roofs and last much longer as well. I am by no means an expert but leaks in traditional roofs generally are a result of UV degradation upon asphalt shingles or wood shakes. In a green roof assembly, this degradation is eliminated.
Also, in attempting to locate leaks, it is much easier to find them in a green roof assembly because the moisture barrier is placed directly onto the roof sheathing (plywood, etc.) meaning that wherever you locate that leak on the inside of your building, the leak is likely occuring at that location on the outside. In a typical roof construction, moisture can penetrate the construction and navigate through cavities of insulationg and enter the interior of a building in a completely different location than where the leak exists. This is what leads to difficulty in locating these leaks.
Again, because there is a lack of UV degregation, green roofs are expected to last much longer than traditional roof constructions. Green roofs are also an initiative that can better our future and even if the above is false, are worth taking a risk on with the hope that our green roof technology will continue to evolve to the point where these worries no longer exist.
Green Roof Life Span
Dear anonymous,
Green roofs are not some new experimental product but rather a tested and proven alternative to standard roofing. There is a long track record of roofs that have been installed and while not problem free they are every bit as reliable as a standard roof. Green Roofs are also a means of providing a multiple environmental benefits while with a superior product that will ultimately require less maintenance than standard roofing methods. The many environmental benefits of a Green Roof are well documented, including green roofs existing schools or retro fitting existing buildings will is one of the best means of mitigating some of the environmental problems faced by our core cites.
• Non-point Source pollution
• Air Pollution
• Excessive Storm Water runoff
• Flooding
• Urban Heat Island
• Lack of Wildlife habitat
• Energy Conservation
• Noise Pollution
• Limited areas for urban green space or community gardens
If saving the planet is not impetus enough to convince the interested party that a green roof is the way to go perhaps value engineering the green roof from a cost benefit stand point will. While a green roof is not always the most cost effective method of roofing more times than not a long term property owner will come out ahead.
Anyway, I guess my point is Green Roofs are a proven sustainable alternative to standard roofing. And while continued discussion is good we need to get past the leak thing, HEAR THAT INSURANCE COMPANIES! There is no shortage of information out there information there, lets inform ourselves of the nuances of green roofs, understand the beniftis and just get it done.
Paul
Post new comment