Rooftop Gardening is Alive and Well Rooftop Gardening is Alive and Well

Rooftop Gardening is Alive and Well

You look out the window on a snowy winter's morning and watch the snowflakes dance around the evergreens and conifers. You finish breakfast and get ready to go to work. Locking the door, you walk to the elevator and...What? Elevator? Yes, elevator. Your view from the breakfast table is a rooftop garden.

Rooftop gardens have grown in popularity through the years. In the process, the gardens are adding to the eco-system by putting more oxygen into the air, Gardeners can enjoy fresh vegetables from their rooftop aerie. Here, we discuss rooftop gardens--what they are, and a few tips and fact on building your very own.

What is a Green Roof?

A green roof is a rooftop layout of vegetation, a growing medium, and a water proof membrane that protects the actual roof. Other components can be added, such as an irrigation system and root barrier drainage system. It can be used in industrial settings, residents, offices, and any property that has a large flat roof. They are widely used in Europe, where they provide not only beauty, but storm water and energy savings potential.

What Kind of Roof Gardens are There?

There are two basic types of roof gardens - the intensive and the extensive. The difference between the two is the requirements. An intensive garden needs these things:

-Requires one foot of top soil
-Can accommodate large trees, shrubs and flower beds
-Adds 80 to 100 pounds per square foot of load to the roof structure
-Is meant to be interactive. Access is encouraged
-Requires significant maintenance
-Needs a complex irrigation and drainage system

An extensive roof top garden has these requirements:

-1 to 5 inches of soil depth
-Accommodates many kinds of ground cover and ornamental grasses
-Adds only 12-50 pounds per square foot, depending on soil type and construction
-Is not designed for public access
-Requires annual maintenance until ground cover fills in
-Irrigation and drainage requirements are simple

What are the Benefits?

The biggest appeal of a rooftop garden is its aesthetic beauty. In addition, a rooftop garden will reduce sewage system overload by absorbing large amounts of water. It will store carbons, absorb air pollution and collect airborne particles. A rooftop garden protects underlying roofing material by eliminating exposure to damaging ultra-violet rays. It protects from extreme daily temperature fluctuations. A rooftop garden reduces energy used because it keeps the interior building cooler.

What About Disadvantages?

Probably the most important disadvantage is weight. If built on an old structure with suspected roof weight-bearing problems, it could cause structural damage. The solution is to downsize, and build a rooftop garden that will not create undue stress on an old building.

Is it Costly?

According to the Environmental Protection Agency (EPA) a rooftop garden costs approximately $8 per square foot to install. This includes materials, prep work and installation. A traditional roof costs about $1.25 per square foot to build, while the installation of cool roof membranes costs approximately $1.50 per square foot. One reason for the higher cost is the lack of rooftop garden builders in the United States. It is essential that you consider the long term savings when deciding on a roof top garden. This savings in summertime energy costs can far outweigh the initial investment in just a few years.

Building a Roof Top Garden

Just about any type of roof can accommodate a roof top garden. People are only limited by their imagination. When building a rooftop garden, be sure that you have a licensed professional check the structural capacity of the building before proceeding. Also, it is wise to check local ordinances to insure it is allowed.

The simplest method of building a rooftop garden is through container gardening. My own personal container garden includes lilac, Cistena Plum, Java Red Weigela, and Dwarf Burning Bush. I also grow tomatoes in containers. Weight is a consideration in my 114 year old building, so an intensive garden would not work well here.

A more complex roof top garden would involve covering the roof with soil. It requires a membrane to be first installed to protect the roofing material from leakage. Then a layer of substrate, such as gravel is added to provide drainage. A filtration mat is usually positioned on top of the substrate. The final layer is soil and plants of choice.

Rooftop gardens are environment friendly, help reduce air pollution, and are a sight to behold. Anyone can build a rooftop garden, if it is no more than containers on an apartment patio. You are only bound by your imagination and desire to bring beauty into your life. Follow these guidelines for success in rooftop gardening.

Alden Smith is an award winning author, regular contributor to and publishes Eco Friendly America. He writes on a variety of subjects, and excels in research.

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