By Tim Husen
When deciding on a healthcare facility, patients may consider a range of factors from quality of care and convenience to the use of cutting-edge technology and innovation. Green roofs, a growing trend across the country, can help set hospitals and clinics apart by contributing to a facility’s sustainability and providing patients with an extra set of benefits such as a beautiful place to sit outside to heal or to observe the serenity from the inside. In addition to providing credit toward LEED certification, green roofs offer aesthetic appeal, especially for patients in long-term care.
However, these roofs also can increase pest pressures for healthcare facilities, which can pose a problem because of the need to maintain a high standard of sanitation. As patients receive care for medical conditions and illnesses, they are sure to be alarmed by any pest sighting, which can severely damage a hospital or clinic’s reputation.
In some cases, pests transmit disease and cause allergic reactions — a serious concern for sensitive patients with already weakened immune systems. Insect pests and rodents also can cause structural damage, surface erosion and damage to electrical wiring. With abundant vegetation, green roofs provide the food, water and shelter that many pests seek.
Common Pests Attracted to Green Roofs
To feature a green roof while mitigating the potential for pests, it’s important to know which pests to look for and what can be done to prevent them. Here are a few common rooftop pests and tactics to identify a potential infestation:
- Cockroaches: The most common sign of cockroach activity is the pest itself. These pests are nocturnal, so seeing just one cockroach during the day could be a sign of a large infestation. If a cockroach is out during daylight hours, it was likely pushed out of its shelter by overcrowding.
- Ants: Ants can nest almost anywhere, including under fountains. Ant colonies can reach populations of 500,000 and uproot entirely if disturbed. They also will leave a chemical scent trail to a food source for other ants to follow – so pay attention if you see them moving in a line.
- Flies: One pair of flies can produce a million offspring through their offspring’s offspring in just a matter of weeks. The most obvious sign of a fly problem are the flies buzzing around. It’s important to keep them out of the building because they can quickly transmit disease as they land on surfaces.
- Rodents: Rats and mice burrow through vegetation and mulch, leave behind droppings, create gnaw marks and make holes around doors and utility penetrations. They also move along walls and leave behind greasy rub marks, which can indicate their path into the building.
Vegetation is the cornerstone of green roofs and also the root of many pest problems. Plants, flowers and water features on a green roof all can attract pests. However, there are ways to strategically plant to avoid attracting more pests to your urban sanctuary. To keep pest populations at a minimum:
- Avoid plants that produce nuts, fruits and seeds. These plants attract pests looking for food.
- Use cedar mulch instead of organic mulch. Cedar mulch helps repel certain types of ants, like the Argentine ant.
- Reduce heavy mulch cover in planters and ivy overgrowth to minimize the food and shelter they provide to pests.
- Check growth areas at the top of plants and on the underside of leaves for evidence of pest activity.
- Talk to a pest management provider about species of vegetation to avoid on a green roof and where to plant to help mitigate pest activity. Wildflowers have the potential to attract stinging insects, so plant succulents, grasses or herbs instead.
Exclusion, Maintenance & Sanitation
If despite the above tactics, you’re overwhelmed with pest issues, another tactic for controlling them on green roofs is an integrated pest management strategy (IPM). This is an environmentally responsible solution to pest control that focuses on multiple control strategies, which may or may not include chemical treatments. A pest management provider will assess the green roofs and building’s weak spots to develop a customized solution that both helps reduce pest activity and prevents pests from getting inside. An effective plan will focus on exclusion, maintenance, and sanitation to protect against pests, with the specific challenges of a plant-filled roof in mind.
For example, many pests can enter a building through even the smallest of holes and cracks. Rats can fit through holes as small as a quarter, and cockroaches can squeeze into cracks just 1/16 of an inch wide. To keep these pests out, here are a few things that you can do:
- Seal cracks, holes and other potential entry points in the exterior masonry with water-resistant sealant and metal mesh. Caulk around utility connections or outlets as well.
- Install door sweeps and weather stripping.
- Keep doors to the roof closed as often as possible.
- Minimize water accumulations from leaky taps, HVAC units and irrigation by correcting drainage blockages and repairing leaks.
- Install and repair window and vent screens.
- Keep trashcan lids tightly sealed and empty trashcans regularly. The odors in garbage cans attract pests looking for food.
- Share sanitation tips with patients and staff so they don’t unknowingly contribute to a pest problem.
By developing an integrated pest management plan, healthcare facilities can proactively protect against pests and their health and financial consequences. To make the most of a pest management strategy, work with a pest management professional to educate staff on best practices. A pest management professional can schedule staff trainings to teach cleaning and maintenance crew the signs of pest activity and practical, everyday strategies for combatting pest-conducive conditions.
Green roofs are well worth the investment as they help reduce energy consumption, mitigate the effect of heat islands, filter air pollutants and provide recreational space for employees and patients. However, without an effective pest management strategy, the greenery could prove more troublesome than expected. By taking a proactive approach, facility professionals can ensure hospitals and clinics — along with their patients — reap the rewards, without issues caused by pests.
Tim Husen, Ph.D., BCE, is a technical services manager at national pest management company Orkin LLC. A board-certified entomologist specializing in urban entomology, he has more than a decade of experience in the industry. For more information, email firstname.lastname@example.org or visit www.orkincommercial.com.