Today's post comes from the October School IPM 2015 Newsletter. Schools and housing are similar in many ways when it comes to the building structure. Think like a pest: it's all about the little entry points. So without further ado, here's the article:
Preventing pest problems begins with designing, maintaining and operating buildings and grounds to reduce food, water and harborage. This month's article features tips on how to effectively pest-proof foundations, architectural elements and roofing for new construction as well as existing buildings.
From the Ground Up
Neglected or poorly constructed building foundations provide an ideal entry point for pests. Regular visual inspections are critical. Dr. Michael Merchant, professor and extension urban entomologist at Texas AgriLife Extension Service, advises, "You always want to have clearance, or a field of vision, around the foundation of a building." Not only does this allow for easier access for inspections, it also denies pests access to concealed travelways and entry points.
Dr. Merchant suggests positioning sidewalks next to the building, with any decorative plantings or shrubs on the outer side of the sidewalk, away from the building. This provides an attractive visual barrier just as if the plants were right next to the buildings. If it's not possible to put the sidewalk next to the building, all plants should be kept a minimum of 18 inches away from the foundation. Crushed stone barriers can also be placed next to the foundation to provide an open space and keep rodents from digging.
Avoid using wood within 18 inches of soil to reduce the potential for termite infestation. Sewell Simmons reports, "The only sure prevention of termite problems is the use of building materials other than materials they thrive on and enjoy consuming." (See "Pest Prevention Construction Guidelines and Practices" in the Journal of School Business Management at http://www.cdpr.ca.gov/docs/pestmgt/pubs/casbo_article.pdf.) Additionally, all materials that contain cellulose including wood scraps, vegetation, stumps and dead roots should be removed from areas under and around the foundation of all buildings. According to Dr. Chris Geiger, municipal toxics reduction coordinator for the San Francisco Department of the Environment, chemical treatments that are put down under the foundation to deter termites generally only last a few years, so they're not a good long-term prevention method. It's also difficult to treat every inch of dirt. Any gaps permit termites to bypass the treatment. Instead, consider solutions such as a layer of sand or other physical barriers such as metal shields under the slab which keep termites out and provide a moisture barrier.
A variety of materials are available to seal foundation cracks and holes, which are common pest access points. Stainless steel batting can be cut to size and stuffed into gaps to block pests. Concrete, expanding foams and caulks are other options for sealing gaps and cracks left by poor construction practices and deterioration. It's critically important to choose the best material for the job at hand. For great information on selecting the right product, see Bobby Corrigan's "Recommendations for Selecting and Using Caulks and Sealants in Pest Management Operations" at http://www.ipminstitute.org/school_ipm_2015/Corrigan%20on%20sealants.pdf.
An Ounce of Prevention
Pest-proofing building designs, as well as conducting regular inspections for pest-friendly deterioration, is a sure recipe for avoiding pest management headaches down the road. Dr. Geiger points out, "Pest management and especially pest prevention is one of the big gaping holes in green building certification programs and building design in general. Just a few carefully chosen design tactics can reduce the need for pesticide use significantly over the life of the building."
For example, bird-proofing after the fact can be prohibitively expensive. Consulting a pest management professional with bird expertise before finalizing designs can be well worth the investment. Facades with fancy detail can provide birds with roosts and perches for nest building. If eliminating ledges from the design isn't an option, Dr. Merchant suggests putting the ledges at a steep angle, at least 45 degrees, which will have the same aesthetic value as traditional ledge angles but will deter bird roosting. Ledges should also be shallow rather than deep, and nooks and crannies should be avoided to eliminate sources of shelter for nesting birds. Dr. Merchant points out that "someone's idea of what might be pretty isn't necessarily a good decision from a pest management perspective."
Particularly in the southern United States, bats roosting in buildings can be a major issue. Bats can transmit rabies and bat removal and cleanup can cost thousands of dollars. Typically, bats enter the building through gaps under roof edging. Since bats only need a 1⁄4- 1⁄2" space to enter a structure, it is important to ensure that all gaps and holes are completely sealed.
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