August 2006 Guest Feature

August 2006 Guest Feature

Chicago’s Hyde Park Art Center has a greenroof of DIY modules, filled with growth and plant media, atop the Hyde Park Art Center building’s existing roof. Photo by Robert Kravitz

By Sandra McCullough, LEED AP

All photos Courtesy GreenGrid ®

F or those of us who know the value of green roofs and are longtime enthusiasts of green roofing systems, each new installation has been considered an achievement for the industry. And now that the movement has garnered considerably greater acceptance with green roofs found on all types of facilities worldwide, we have an opportunity to concentrate on specific markets that have yet to take advantage of green roofing systems.

One such market is residential—and more specifically, individual home owners. Roofs of any kind are rarely on the mind of most home owners, and when they are, it is often because they need to install a new roof or repair an existing one—both of which are usually costly expenditures.

Encouraging home owners to add a green roof atop an existing roof has been a challenge, not only because of the added expense, but because so few home owners know what a green roof is, its benefits, its long-term cost savings, or how easily it can be installed. Although small green roof undertakings may be easy do-it-yourself projects for the average weekend warrior, more extensive green roof systems can still be perceived as daunting in terms of buying the right materials, installing the layering, and including the important perimeter, flashing, and drainage outlet details.

This is changing now with the introduction of do-it-yourself (DIY) modular green roofing systems. These systems have helped reduce the expense of green roofs significantly because they are designed for self-installation, eliminating much of the labor costs.

Rooted on the Roof: A Brief History

Although green roofs on homes are relatively rare in the United States, the concept is not a new one. Green roofs have been found on Scandinavian, German, British, and Irish homes for centuries. Even some early American prairie homes in Iowa, Nebraska, and other states had green roofs of sorts decades ago.

These sod houses with sod roofs used a layer of grass, grass roots, and other plant media as a construction material, especially in those areas where other types of construction materials such as bricks and lumber were not as readily available. A sod covering that was historically a material of choice in the United States was frequently referred to as buffalo grass. It had a thick root system that would be plowed into long strips and then cut as necessary to be stacked on the house—roofs, walls, and all.

Often the grass would stay green and continue to grow on the outside even after being placed on the house. This would sometimes attract goats, cows, and other animals that grazed on the surface, acting as living lawn mowers. The big benefit of sod for the home owner was its insulating qualities. Sod homes tended to stay warm in the winter and comfortably cool in the summer—one of the benefits attributed to green roofing systems today.

Modules Make the Difference

However, as mentioned earlier, one of the big obstacles to green roof installation, especially for home owners, has been the cost. With the traditional built-in-place green roof, several workers are often required to haul plants and soil to the building top where the green roof is installed.

In addition, a built-in-place roofing system can take many days to install on a home. If several laborers are brought in to install the roof, this increases the concern that an accident might occur. Often this concern translates into higher insurance costs for the roofing contractor, which is passed on to the home owner.

Modular green roof systems are an alternative to built-in-place systems. They help eliminate many concerns about safety risks and reduce the cost to install a green roof.

One such system, the GreenGrid® Do-It-Yourself (DIY) Kit just introduced by Weston Solutions® uses lightweight 2′ x 2′ x 4 modules made of 60 percent recycled plastic. The Kit is delivered directly to the homeowner or installation site and consists of four main components: the plastic modules just mentioned, geotextile root and soil barrier, growth media, and plants.

Different plant palettes are also available. Plant selection is based on the region of the country where the green roof is to be installed, as well as hardiness, drought tolerance, and low maintenance. Additionally, because green roofs can be visually appealing, the selections have varying foliage and flower colors, which bloom at different times of the year.

As with all green roofs, there is periodic maintenance, at least initially. If natural precipitation is insufficient, the plants may need to be irrigated during the “establishment period,” which usually lasts for four to six months. Occasional weeding may also be required during this period. Although the growth media is specially prepared for the roof, application of slow-release fertilizer once or twice per year may be required for plant nutrients.

Requirements

As with any green roof project, certain installation requirements must be followed for all DIY modular systems. For instance:

Structural Capacity: The home owner may need to consult with an engineer to determine if the home can support a green roof. The GreenGrid modules, for example, filled with plants and growth media, weigh 15 pounds when fully saturated.

Existing Roof Condition: The existing roof surface must be in good condition and free of leaks. If repairs are needed, these should be completed before the green roof is installed.

Maximum Slope: This can vary with the type of DIY system installed, but for a GreenGrid modular DIY green roof system the slope must be 5 percent or less.

Permits: The home owner must secure any local permits and/or approvals that are required.

Installation: DIY systems are designed for home owner installation – see pointers below. However, some home owners prefer to have roofing or landscape contractors install the green roof. (See below for step-by-step installation instructions.)

DIY System Installed on Arts Center in Chicago

To help celebrate the opening of its new location in April 2006, Chicago’s Hyde Park Art Center asked area artists to create new work for the local community to enjoy.

One of the projects that has garnered considerable attention—and is now a permanent exhibit—is the building’s green roof.

The DIY modules atop the Hyde Park Art Center is a permanent art display as well as an environmentally friendly greenroof. Photos by Robert Kravitz.


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