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Exciting news about moss for green roofs…
During 2008 Moss Acres conducted several experiments with moss on a wide range of green roofing soil mediums and on a green roof atop a springhouse. The results have been very favorable. We have found that by grinding two varieties of our mosses (hypnum – sheet moss and dicranum – rock cap) and broadcasting these fragments over the expanded aggregate, we have been able to establish moss that not only knits together quickly, but also grows into and amongst the aggregate, locking the moss to the roof.
The keys to success have been keeping the moss fragments moist (gel powder is first lightly sifted onto the roof), choosing a relatively shaded location, and utilizing a relatively high coverage rate of 65% - 85%.
Building on our success with the moss covered springhouse roof, Moss Acres began providing moss for additional green roof projects in early 2010.
The first was a shaded section on a flat roof at the Russel Wright Design Center in Garrison, New York. Michael Franco, Landscape Architect for Town and Gardens, Ltd., designed the roof and specified a mix of hypnum and rock cap mosses for the shaded section, and sedum for the section with more sun exposure. The moss roof was installed over a Kemper membrane with a drainage/retention layer by Drainage Products, Inc., and extensive green roof growing medium by Sky Garden.
The next project was at the residence of none other than Dave Benner, moss pioneeer and father of Moss Acres owner, Al Benner. This roof, over a section of the house measuring 550 square feet, had a 10° pitch and was well shaded under a large beech tree. Five years earlier, the roof had been covered with an EPDM rubber roof. For this installation, the entire section was covered with a Colbond Enkadrain “retain and drain” mat system, a Rooflite® extensive growing medium, and a mix of pre-shredded hypnum and rock cap mosses that were applied to achieve a 75% coverage rate. Prior to spreading the moss, which was done by hand, a water-retention gel was raked into the growing medium. The last thing to go down was a powdered tacifying agent, which will help the moss fragments attach to the gravel-like growing medium. Special thanks for on-site support to Charlie Miller and his team from Roofscapes in Philadelphia, PA.
To establish a green roof using moss on a relatively flat, shaded roof, the steps are incredibly simple:
Please call 610-635-4144 to discuss in detail any green roof project for which you might be considering moss. Remember, the species of moss currently offered by Moss Acres thrive in shaded areas. Some partial sun can be tolerated, but lengthy periods of afternoon sun on a roof are not recommended. (Note: We are currently experimenting with sun-loving mosses for roofs, so feel free to inquire for up to date information).