This week I want to share another article from the School IPM 2015 Newsletter. When thinking about the "building envelope," many structures are similar—especially from the perspective of an ant or mouse! I took out some school-specific language, made the major points bold, and added one notes in italics based on my observations at PHAs. Thanks to the folks at School IPM 2015 for providing another great resource!
Designing, maintaining and operating buildings and grounds with pest prevention in mind is an enormous time and money saver! Here we focus on doors, windows, exterior lighting and landscaping in new construction and existing buildings. If you missed Part One on foundations, roofing and architectural elements, please see the October School IPM 2015 eNewsletter.
According to Dr. Michael Merchant, professor and extension urban entomologist at Texas AgriLife Extension Service, pests are much like people in that "Doorways are probably the number one entry point for pests into a school." It's important to ensure that all doors are well-designed and installed, and are equipped with either rubber or nylon brush door sweeps. All doors should be inspected after installation, ensuring that there are no gaps or spaces around the frame and the door closes tightly. Pay close attention to the ends of the sweep—mice and other pests will try to wrap around the corner of the door frame to get in. Dr. Chris Geiger, municipal toxics reduction coordinator for the San Francisco Department of the Environment, emphasizes that doors should have no more than ¼ inch of clearance. If you can slide a pencil under the door, the gap is too big. University of Florida data shows that effective door sweeps alone can cut pest complaints by 65%!
In addition to making pest access into the building more difficult, door sweeps also block air flow, keeping dirt out and reducing heating and cooling losses. Self-closing doors can be used to prevent doors from being left open inadvertently. Dr. Merchant asserts that schools need to take responsibility for these details; architects and building contractors simply don't have pest prevention at the top of their priority lists.
Windows are another common pest entry point. All windows should be tight-fitting and should include well-maintained screens. An article by Sewell Simmons in the Journal of School Business Management entitled "Pest Prevention Construction Guidelines and Practices " states that, "Screens on windows, crawl spaces, and vents are often damaged in school buildings. Check these carefully for needed repair or replacement." Dr. Geiger suggests looking into Teflon coatings or bird-repellant gels for exterior window ledges, which may provide a surface that's too slippery or sticky for birds to roost comfortably.
School IPM 2015: A Strategic Plan for Integrated Pest Management in Schools in the United States recommends that "weep holes, or openings in masonry to allow moisture to escape, are screened to prevent pest access, e.g., stinging insect nesting." Fine net screens or stainless steel batting can be used to prevent pest entry through weep holes, as long as they allow water to escape.
We're all familiar with how insects can be drawn in by sources of light at night. Since doorways are so critical to keeping pests out, sources of light should not be mounted above doorways, but rather on poles away from the building, with the light directed where needed. The International Dark-Sky Association provides guidelines on lighting that reduces light pollution. Low-UV-production bulbs, such as yellow insect lights can help reduce attraction. Sodium vapor lights are also an option, however these require special light fixtures rather than simply replacing a bulb.
One of the easiest mistakes to make in landscaping is choosing plants based on their dimensions when planted, rather than size at maturity. Shrubs are often planted too close together, obscuring the ground and creating harborage for rodents and insects.
Trees can grow into power lines or too close to buildings, allowing branches to provide easy access for insects and animals to buildings. Tree and shrub branches should be kept at least six feet away from structures, and ten feet if tree squirrels are a problem.
Decorative elements such as lattices and vines climbing up the side of buildings can also provide bird roosting sites and a handy ladder for roof rats—avoid these if possible. Dr. Merchant also suggests choosing native plants and those that are well-adapted to your area. These varieties may be more resistant to the common pests in your locale, requiring less pest prevention and elimination. If you have questions about pest-resistant plants, consult your cooperative extension service for recommendations.
Sidewalk cracks can provide an ideal place for weeds to thrive, and can also act as pathways for insects such as ants. Any cracks should be filled with an appropriate sealant or concrete. Dr. Geiger suggests installing concrete, brick or paver mowing strips under fences and around buildings and plantings to prevent weeds from growing in locations that can't be easily mowed. Mowing strips save on labor and reduce the need for pesticides to control weeds in unmowable areas.
Good moisture control can help with the management of subterranean termites, carpenter ants and some wood-boring beetles. Simmons' article provides good tips for reducing moisture, such as using moisture barriers in both above-ground and slab foundations. Additionally, all exterior grades should be sloped away from the building to provide good drainage and prevent moisture from building up. Sprinkler irrigation heads should be aligned and/or shielded to keep spray from hitting buildings. Foundation wall vents should be included to provide cross-ventilation for buildings with crawl spaces.
With a little effort and foresight, any housing authority can pest proof their buildings to keep out unwanted critters and reduce the need for chemical prevention.