
Who wouldn’t want a green roof? Nice to look at, fun to hang out on [in the case of roof gardens], they probably smell great [must be better than rubber+tar] - and oh yeah, they’re super for the environment. They reduce urban heat island effect, reduce water runoff/contamination, protect the existing roof from harmful UV rays, encourage [supposedly] the return of some indigenous species [birds, insects, etc.], and they clean the air. Super - if only there were a book released in late 2007 from PA Press that both gave a history of green roofing, an explanation of how they work, and provided an in-depth example of an existing roof that was converted to a green roof…
Enter Green Roof - A Case Study by Christian Werthmann - a book chronicling [in depth] the design and construction of a green roof for the American Society of Landscape Architects‘ headquarters in D.C. The ASLA hired Michael Van Valkenburgh Associates, in collaboration with the Conservation Design Forum, to design the green roof ‘hybrid’ - meaning that it would be both a ‘green roof’ and a ‘roof garden’ [a distinction made clear in the case study]. The 3,300 square foot completed roof meets all the sustainable + aesthetic criteria mentioned above, and provides a rooftop hangout for the ASLA.
Tremendously informative, Werthmann’s book covers just about everything you could imagine and more. He starts with an essay on green roofs [Part I] - describing the types of green roofs [green roofs, roof gardens, hybrids], the conditions at the ASLA headquarters, the history of green roofs, precedents, construction/planting techniques, bioengineering, regionalism… and more. He also gives an in-depth description of the ASLA roof as it was proposed, including renderings, an explanation of the design, the intent, and the benefits of the roof. Part II is then additional information on the ASLA roof, followed by a number of photographs of the finished product.
The third part of the book - Part III: Roof Index A-Z - is really where the best information lies. Werthmann breaks down the project to it’s individual pieces, from air handlers to visibility, biodiversity to the 2 ‘waves’ designed by Michael Van Valkenburgh Associates. This section gives a description of each of the design issues that were faced on the project, along with an explanation of how they were solved - providing sketches, before and after photos, diagrams, plans + sections…everything. All questions are answered.

Basically, if you’re looking to learn more about green roofs [or roof gardens, or hybrids] this book is a great place to start. It gives an incredibly detailed look into the inception, design, and construction of a green hybrid roof system [in a temperate climate] - earning it a place on any seriously green ninja’s bookshelf.

Christian Werthman’s Green Roof - A Case Study can be purchased here from the MNP store or here from the publisher, Princeton Architectural Press.
Also, be sure to check out ASLA’s blog, The Dirt and their own info on their new green roof - including webcam videos and a virtual tour.
::Special AMNP thanks to Russell and the people at PA Press for generously supplying a review copy of this book::
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