The Guild Report:  
Is your Landscape over a
Rooftop or Parking Garage?
June 2012 
In This Issue
Point of View
Above Ground Landscapes
Designer Chicken Coops?

Point of View  
With Employee Owner
Paul Swanson 


  Paul S EarthDay 2010


"As a long time employee-owner at Gardeners Guild, I continue to be impressed about how well our divisions collaborate to serve customers.  Because many of us are long time employees, the depth of knowledge and skill are a tremendous   benefit for our clients.
Paul is our Director of Business Development.  He has a BS in Horticulture from Cal Poly, has been with Gardeners' Guild for twenty three years; is Landscape Industry Certified and an ESOP* Trustee.    

*ESOP - Employee Stock Option Plan


Over Structure Landscape Project 
Construction & Container 







If you manage or own a commercial building in San Francisco or Oakland and it is landscaped, there is a good chance that it is what is called an "over structure" landscape.  This just means that your landscape or garden is built over a structure - such as a balcony, roof or parking garage. 
In fact, any urban above ground courtyard space landscape is likely to be this type of landscape.


Our cities are sprinkled with dozens of them.  They add to the value of the building and provide beautiful green spaces for gathering.


They may look just like a street level landscape but that is where the similarity ends.  The requirements for building and maintaining these landscapes are quite different.


The article below details their challenges, potential problems and best practices.   We hope you find the information useful. 


We welcome your comments and suggestions. 


All the best,
Suzanne Harris

Rooftop and Over Structure Landscapes


Because there is a structure below the landscape, not soil, it cannot be overstated - that an improper installation may not become apparent until the plants are stressed, in decline or even dead. 


A rooftop or over structure landscape can have soil depth of less than a foot to five feet or more. It consists of several layers: root barrier, waterproof membrane, drainage layer, soil, plants and irrigation. 


Below is a description of what are essential considerations of over structure landscapes.  It explains what can go wrong why you need to have a contractor who is knowledgeable about urban landscapes to design, install and maintain your above ground landscape.



Leakage is one of the worst problems.  Unfortunately, it is not always noticeable until the water has already leaked into your building.  The waterproofing liners have a lifespan and it is important that your landscape maintenance contractor pays attention to any potential leakage. Waterproofing is done by a contractor who specializes in waterproofing.



Contrary to what you might think, the right kind of soil for an over structure landscape is soil with a high mineral content so it does not break down.  These ideal soils are not readily available and must be specially designed and blended for best results.  Improper soil types can result in a drop in soil grades which can expose utilities, irrigation pipes and waterproofing liners.  Conversely, in a typical landscape you want soil that has a higher percentage of organic matter which will decompose - contributing to fertility of native soils.  Consequently, specifying the proper soil for an on-structure landscape installation is a critical step to ensuring long term success.      



It is important to keep in mind a few points:  You don't want to water too deeply and you will need to minimize runoff.  For many over structure landscapes spray irrigation is the best solution unless high wind or blockage from plant material is a factor.  Spray irrigation enables more accurate management of moisture in the top few inches of soil  Drip irrigation typically creates a deeper moisture profile leaving upper soil layers dry which promotes root development at the bottom of planters within drainage layers.  Over structure irrigation is challenging so it is important that your contractor be knowledgeable about appropriate irrigation technology and performing proactive irrigation checks and repairs.  For maintenance, irrigation checks should be done more frequently than with in ground landscaping. 



Water needs to be able to flow unimpeded through soil towards the drain outlets.  Features to expedite this water movement to drains should be included in any renovation or new construction.  It is another reason that this type of landscape needs to be closely monitored.  A drain can easily get clogged and it would not necessarily be noticeable until a tree dies or flooding occurs.   When we build over structure landscapes we include either french drains or composite drain layers to be sure water will move through the soil to the drainage outlets quickly.     


Avoid deep rooted plants or those with aggressive rooting habits.
Overall, it is better to plant smaller, slow growing trees.
As an example, trees to avoid planting would be Poplars and Liquid Amber which are both fast growing with aggressive roots. 


Designer Chicken Coops?

Driving the road that leads to my house I often notice one lone chicken wandering the street.  I'm guessing it's my neighbor's.  A friend of mine says that when she moves to the country she wants to raise chickens.  I'm hearing more about chickens and chicken coops lately.  Perhaps it's because its become the latest craze.  Not just in the country, but its popular in the city, too.  Chicken coops are sprouting up all over; upscale chicken coops!  
My recent google search for "Chicken Coops in Marin" yielded six local companies selling their chicken coop designs.  One such outfit is called "Wingman Coops".  Their website says they design chicken coops for the discriminating backyard chicken enthusiast.
Sunset Magazine says that the chicken coop is the next doghouse!
There is even a blog called urban
For more information about Wingman Coops.