Featured Article

Installing Modular Vegetative Roof Systems

Offers Growth Opportunities

by Kate Baumann

Although the recession has battered both the housing and commercial construction markets and curtailed the work available to contractors in the building trades, there are pockets of opportunity. For roofing contractors who are open to new approaches, there is a genuine growth opportunity in the installation of vegetative roofs using modular vegetative roofing systems.

Historically, vegetative roofs were built-in-place systems designed and installed by landscapers working with architects and horticulturists - with the result that sometimes scant attention may be given to the integrity of the roofing system by the vegetative system installers. However, the relatively recent introduction of modular systems gives roofing contractors the opportunity to take the lead on vegetative roof installations without involving landscapers or horticulturists.

That's because manufacturers of today's modular roofing systems will provide roofing contractors with installation training and all of the components necessary to create a complete vegetative roof. Modular systems typically include the following elements:

Lightweight, movable trays or modules complete with growing medium (more than just soil, it's typically a proprietary blend of organic and inorganic materials) and plants which have been pre-selected by the manufacturer's staff horticulturist to be appropriate for the climate in which they will be installed. Sedum, a drought-resistant perennial that comes in a variety of colors is a popular choice for vegetative roofs.

Trays/modules come in a variety of depths and sizes to accommodate a variety of plant types and vegetative designs. Depending upon the type of plants selected, the trays are sometimes lined with fabric which permits storm water to filter through the tray without allowing the growing medium to wash away.

Generally, the trays can be set directly on a properly installed TPO or EPDM roof membrane that is in good condition and arranged according to a predetermined design. The trays may be ordered pre-planted with seedling plugs that will grow into mature plants, or for a roof that is "instantly" green, trays with mature plants are also available.

In addition, the GreenGrid® system offers Ecoballast® modules that are filled with stone ballast. These modules can be custom-drilled with the appropriate number and size of holes to manage storm water run off through the retention and detention of rainfall.

Edge treatments in painted aluminum or steel to finish the design are also available for aesthetic purposes, but are not required as they are for built-in-place systems.
Other optional elements such as drip irrigation systems, pavers, walkways, water features and planter boxes can be incorporated into the system.

Modular vegetative roofs offer multiple benefits for both contractors and building owners.

They are more cost-effective than built-in-place vegetative roofs.
All system components are engineered to work together for easier, faster installation. The pre-planted trays and modular design allow work to continue even in rainy weather.
No special tools are required for installation. Trays can be moved easily and then put back in place without disturbing the growing medium or the plants, a real plus when roofing system maintenance is required.
A modular vegetative roof can be installed in sections and altered or rearranged in the future.

The detailed information necessary for successful modular vegetative roof installation is available through contractor training programs offered by manufacturers of modular vegetative roofing systems.

However, even with a turnkey vegetative roof system and manufacturer-sponsored-training, it is essential that roofing contractors have a clear understanding of their responsibilities in vegetative roof installations and how they, as roofing experts, can add value to the process.

Before any installation begins, it is essential that the roof structure be evaluated and approved to safely carry the added weight of a vegetative roof system. This is the building owner's responsibility, but the roofing contractor's checklist should include obtaining proof that the roof will meet the necessary load-bearing requirements.

Similarly, it is the building owner's responsibility to verify the water-tightness of the existing roof system. Here roofing contractors can offer their expertise to verify the condition of the existing roof. During this roof inspection, the contractor can also identify the locations where there are penetrations in the roof that will require proper finishing with ballast material to meet firebreak requirements.

In preparation for the installation, the contractor should stage delivery so that only the number of trays that can be installed in one day are delivered at a time. That is to ensure that the trays are not left stacked up at the job site for days on end. These are living plants that need water and sunlight to thrive and the sooner they are installed in the roof environment, the less potential there is for plant damage or loss.

Once the roof has been installed, maintaining the vegetative roof system - initially that is primarily watering and weeding - becomes the building owner's responsibility. However, ongoing maintenance of vegetative roofs offers roofing contractors another potential revenue stream. Some roofing contractors are already selling maintenance services for conventional roofing systems and adding vegetative roof maintenance to the portfolio of available services is another way to offer protection for the entire roofing system.

Vegetative roofing system manufacturers will provide recommendations for long-term maintenance schedules and offer special instructions for drought conditions. A roofing contractor interested in offering vegetative roof maintenance could either hire or train staff to handle these specialized tasks such as trimming, pruning, and pesticide applications, or subcontract them to plant maintenance specialists.

There will always be a demand for built-in-place vegetative roof systems that offer the flexibility in design and plant material selection necessary for elaborate rooftop landscapes. However, modular vegetative roof systems put appealing rooftop landscapes within reach of many building owners and enable roofing contractors to participate in the 21^st century "green revolution."

To learn more about vegetative roofs, go to www.mulehide.com and www.greenroofs.org. For contractor training, contact Mule-Hide at 800-786-1492 and ask for a Mule-Hide Living Roofs^TM sales representative to contact you

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Kate Baumann is Director of Marketing, Customer Service & Procurement at Mule-Hide Products Co. Inc. (www.mulehide.com), supplier of Mule-Hide Living Roofs^TM featuring GreenGrid^® modular technology, as well as other premium-quality, high-performance, low-slope roofing products and systems that meet current and emerging needs of the design community with a strong focus on sustainable solutions. She can be reached at (608) 361-6812 or kate.baumann@mulehide.com.