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Read Text Only: Green Feature
Living Roof - California Academy of Sciences


In case your only green knowledge has been about the *cough* alternative kind of movement these last couple of years, you should know that the California Academy of Sciences is setting the standard for sustainable living with 1.7 million native plants living on its roof. The original sketch of the building in 2001 by Italian architect Renzo Piano was a design that would metaphorically lift up a piece of Golden Gate Park as the museum was slid underneath. Nine years later, the roof is in full bloom and the CAS is the “greenest” museum ever constructed.

We were lucky this month, not only because of some beautiful breaks from the rain, but also because we were able to accompany the Chairman and Senior Curator of Botany at CAS, Dr. Frank Almeda, on a tour of the living roof. Passionately involved with the roof since its conception, Dr. Almeda told us everything about it, from its resident albino poppy – yes, that’s “poppy” and not “alligator” - to why city pigeons and rodents don’t like the roof.

We’d like to give you the facts about the living roof because hey, it’s a very impressive green roof and every San Francisco resident should learn how to live sustainably, but we also wanted to know what Dr. Almeda had to say about taking on a similar project for your own roof. Besides the obvious “you must be entitled to the space on your roof” clause that’s probably in your lease, here’s what we found out:

1. Hire an architect or enlist the knowledge of an architect friend to determine if your roof can bear the weight of plants and their support systems.

2. Calculate your water usage and conservation needs. Now would be a good time to get that rain barrel you always wanted to try out.

3. Expect your initial project to cost around $17/sq. ft., but to save you thousands in energy costs over the life of your living roof and to last 25 years longer than a traditional shingled or clay tile roof.

4. With San Francisco’s weather, you’re probably used to layering, so apply this to setting up your foundation. Start with a lightweight concrete and steel frame roof (one that can bear the load, remember?), you’ll then add a waterproofing layer (much like a roofing shingle), an insulation layer, an egg crate-like drainage layer, an erosion control layer using chicken wire and substrate, and 3” deep biodegradable coconut husk trays for planting your seedlings.

5. Educate yourself about native plants and their ecological and chemical requirements. Just because you want to blanket your roof with invasive ice plants or Russian olive trees in containers doesn’t mean it will function as an energy-conserving “green” roof. For 100% coverage, try some Columbine, Beach Strawberries, Beach Daises, and Self Heal (Prunella). Having a variety of low laying, lightweight plants will provide habitat for birds, bees, and will naturally retain moisture and nutrients with minimal weeding.

There you have it, San Francisco! If you want to live more sustainably and healthily by preventing dirty water runoff from your building, filtering urban noise and pollution, and conserving energy by allowing plants to do the evaporative cooling and heat loss prevention for you, then what are you waiting for? They’ve been doing it in Scandinavia for centuries and the best part is, this garden won’t get you busted by the cops.