Reprinted with permission from the California Association of School Business Officials. Simmons, S. 2005. Pest Prevention Construction Guidelines and Practices. Journal of School Business Management 70(4): 10-16. Pest Prevention Construction Guidelines

and Practices By Sewell Simmons

revention is the key to gas lines, and communication cables The following guidelines and prac- effective, least-hazardous generally have large openings that per- tices illustrate the variety of methods pest management pro- mit pest entry. Wall cavities, ceiling cav- that can be used and their value in grams in schools,” advises ities, and the space beneath floors can pest prevention. Sources listed in the Mary-Ann Warmerdam, all provide pest shelter. From these Reference section offer many additional “Pdirector of the Department of Pesticide areas, pests generally have ready access suggestions. Regulation (DPR). to the rest of a building. Utilities, over- “If the conditions that attract and head suspended ceilings, and air condi- Construction Guidelines support pests—the presence of food, tioning ducts provide a very effective and Practices water, shelter, and access—are not elim- pest distribution system. inated, then other management prac- Although pest-resistant building Foundations and Slabs tices are likely to fail,” said Director practices most commonly reduce shelter Exclusion Warmerdam. “Everyone involved in the and access, they can also reduce food • Eliminate gaps or flaws in foundations planning, design, construction, remod- and moisture sources through proper and slabs, or where the wall framing eling or retrofit of school buildings sanitation, reducing trapped moisture, meets the foundation or slab floor; should be aware of the need for long- and improving drainage. • Install physical barriers beneath joints term prevention or suppression of pest While proper construction practices or other discontinuities in the founda- problems. Pest prevention will reduce are the emphasis here, they cannot stand tion. No hidden cold joint should overall costs of pest control operations, alone. A strong preventive maintenance exist in the foundation unless there is as well as other maintenance and oper- program is essential. Poor sanitation or a physical barrier. A sheet metal barri- ating expenses,” she concluded. leaving entryways open will make even er to termites can be installed from A thoroughly integrated approach to the best-designed and constructed build- below the wall sill plate or first block pest management in school buildings ing susceptible to pest problems. Using course horizontally to embed in a begins in the early planning stage. Too the practices discussed below, together mortar joint; often, pest management is not considered with routine inspection and awareness of • Include the design of footings for brick, at this point. The way a building is put potential pest problems, can greatly stone, or other veneers with the other together—including materials, construc- reduce or eliminate the potential for pre-construction foundation planning. tion techniques, and attention to detail— infestations especially when followed by A concrete bearing ledge that is poured will impact future pest prevention efforts responsible maintenance. For more infor- integrally (monolithic) with the con- throughout the life of the building. Con- mation about pest prevention and main- crete foundation should support these sidering pest management needs during tenance go online to www.schoolipm.info heavy veneers. If poured as part of the design, development and construction to the “Managing Pests” link, then to the foundation, the ledge helps prevent ter- means to incorporate features that will “Pest Prevention and Management” link, mite entry into the building between exclude pests, minimize pest habitat, and then “Pest Prevention—Maintenance the footing and the foundation; promote proper sanitation. Practices and Facility Design.” • Use a sand barrier. Use a three-inch Several basic structural features cause layer of sand underneath most pest problems. Many buildings A thoroughly integrated slab construction. Use have pest exclusion problems at door- one to three-millimeter ways and windows. Heating, air condi- approach to pest management particle size in place of tioning, plumbing, electrical service, unsifted sand to provide a and fire sprinklers provide other pest in school buildings begins in permanent termite barrier entry points as well. Even in new build- (western subterranean ings the electrical conduit, water and the early planning stage. and Formosan termites);

10 CASBO JOURNAL JULY/AUGUST 2005 from the crawl space and within one foot of the perimeter of the building. Moisture management • Eliminate sources of chronic moisture in and around the structure. This is one of the most important requirements for successfully managing subterranean ter- mites, carpenter ants, and some wood boring beetles. Good drainage design will help to prevent moisture buildup in and around the structure; • Use moisture barriers. In above- ground foundations, moisture barrier films such as six mil polyethylene can be used to cover the area under the structure. Some builders recommend the use of moisture barriers under slab foundations as well; • Slope all exterior grades away from the structure to provide drainage; • Construct and seal all adjoining com- ponents such as porches and planter boxes to prevent moisture and soil contact with the structure; • Design exterior landscaping to avoid moisture build-up around the founda- tion. Maintain clearance between veg- etation and exterior walls; • Use naturally durable wood or non- cloth to exclude rodents). Be sure to • Align and/or shield sprinkler irriga- wood materials (more information add ventilation, should the material tion heads to direct spray away from accessible on these materials at installation reduce air flow by reduc- the building; and www.mcvicker.com/twd/gwdi97/page ing the square inch of vent space to • Place foundation wall vents to provide 000.htm). The only sure prevention of area ventilated equation below build- cross ventilation for buildings with crawl termite problems is the use of building ing code requirements. A general rule spaces. If regrading or remodeling cover materials other than materials they of thumb is 150 square (sq.) inches of vents, additional vents may be needed. thrive on and enjoy consuming; vent for every 100 sq. feet of under- Facilitate inspection and maintenance • Eliminate all wood-to-soil contact. building coverage. • Provide adequate clearance to allow Soil should always be from six to 18 Harborage reduction access for inspection and control if inches below any wood member — • Avoid burying or storing cellulose- needed. Construct decks, fences, patios, the greater the distance, the better; containing material (wood scraps, planters, or other wooden structural • Extend foundation below ground. form boards, vegetation, stumps, large components that directly abut the side- Good foundations will normally stop dead roots, cardboard, trash, and for- wall of the foundation or structure to rodents from getting into buildings; eign material) near the structure; provide: (a) an 18-inch clearance however, if foundations do not rest on • Prior to concrete placement, remove beneath or, (b) provide for six-inch bedrock, they should extend vertically all cellulose-containing material from clearance between the top of the com- below ground at least three feet or the area encompassed by the founda- ponent and the exterior wall covering have an L-shaped curtain wall about tion and the area within one foot of its or, (c) have components that are easily two feet deep with a one-foot projec- perimeter. The fill material should be removable by screws or hinges to allow tion from the building; free of vegetation and foreign material; access for inspection of the foundation • Modify foundations on older build- • Prior to concrete placement, clean all sidewall and treatment for termites. ings with concrete or non-corrosive cellulose-containing material from cells metal barriers to stop rodents from and cavities in masonry units, and Floors digging their way in; and from air gaps between brick, stone, or Exclusion • Check foundation vents to make sure masonry veneers and the structure; and • Eliminate gaps around floor joists. they are tight and appropriately • After all foundation work is complet- Floor joists should be built in or fitted screened (one-quarter inch hardware ed, remove all loose wood and debris onto joist hangers.

CASBO JOURNAL JULY/AUGUST 2005 11 Facilitate sanitation/harborage may hide. Dead spaces include double Facilitate inspection and maintenance reduction walls, false ceilings, enclosed staircas- • Build in inspection and maintenance • Build floors to be durable, non- es, boxed plumbing, and voids (false access. Suspended ceilings are helpful absorbent, anti-slip, without crevices, bottoms) under cabinets. in hiding horizontal pipe work and and capable of being effectively Harborage reduction services but access for inspection for cleaned. If concrete is used it must be • Do not use wall coverings that provide pests and maintenance must be built steel-float finished and sealed. Slope insect harborage. Do not install peg- in. Structural walkways should always floors sufficiently for liquids to drain board in kitchens, or other food service be provided in large premises. to trapped gullies or drainpipes. The areas, animal rooms, or laboratories. Utility Entry Points floor area under food preparation Facilitate sanitation equipment should allow easy cleaning Exclusion • Construct walls for easy cleaning. of food spills and remain open to pre- • Seal utility entry points on the build- Wall surfaces are best when smooth, vent harborage. ing exterior. Junctures where utilities impervious, non-flaking and light-col- such as pipes and cables enter struc- ored, and must be capable of being tures require special consideration to Good foundations will thoroughly cleaned. Do not use prevent pest entry; normally stop rodents from absorbent emulsion paints. Stainless • Seal entry points within the struc- steel splash-backs are recommended ture. Once inside the wall, pests may getting into buildings. behind sinks and working surfaces; gain entry into the main structure • Use durable, non-absorptive shelving along electrical lines, pipes, poorly material. Keep shelving far enough sealed fire wall sheathing, or around Moisture management away from walls to leave room for • In areas where hazard from termite furnace ducts, hot water heaters, or cleaning; and laundry drains. If pests are able to damage is most critical, use floor • Areas where susceptible items are reach the attic, they may travel from framing of naturally durable wood stored should be well lighted for ease room to room or unit to unit and use other applicable methods of in cleaning and inspection. termite protection listed above for through openings for pipes, ducts, Moisture management foundations; and and wiring; • Ventilate cavity walls. Adequate venti- • Provide adequate ventilation. Allow at • Pipes, ducts or cables passing through lation must be provided but any least 18 inches of clearance under walls should fit tightly or be built into openings into the roof for this pur- floor framing and at least 12 inches fire stops. Protect joists with metal pose must be screened with mesh or under floor girders. flanges where pipes or ducts pass hardware cloth. through floors and walls. Hot water Inside Walls, Cabinets, Shelving, Ceilings pipes should be carried in sleeves Storage Rooms through vertical or horizontal partitions. Exclusion Exclusion Surround the base of elevators, convey- • Eliminate gaps around joists. On • Install wall cavity closures and avoid ors and machinery with a two-foot high multi-story buildings, floor joists joist/rafter gaps. This will keep out smooth metal fence; conveyor ends should be built in or fitted onto joist various pests that have gained access should have tight-fitting doors. Seal hangers; and to the attic such as birds, mice, rats around all electrical conduits, plumb- • Seal all internal partitioning wall and and squirrels (squirrels are an increas- ing, heating pipes, trunking or service ceiling cavities. ing problem in roof assemblies); ducts that pass through them; and • Eliminate gaps around wall penetrations. Facilitate sanitation • Seal duct work. Ensure that all heat- Wherever drains, hoists, and vents, con- • Build for ease of maintenance. Sus- ing and air conditioning ducts are veyors, pipes, cable conduits or ducts pended ceilings should be made of tightly sealed at seams and joints. pass between buildings through walls or metal lattice incorporating cleanable Harborage reduction foundations, they should be sealed to panels. Aluminum backed and faced • Ensure that all pipe insulation has a prevent the spread of any infestation fiberboard has proved successful in smooth surface and that there are no from one building to another; many food factories. Flush-fitting gaps between pieces. • Equip storage areas with self-closing ventilation grilles should be installed doors to deny pest access; tightly enough to eliminate openings Facilitate inspection and maintenance • Eliminate cracks and crevices (i.e. around the edge of the grille. Solid • When installing pipes, cables and with sealant, or copper or bronze ceilings should be well insulated to fittings, build in or allow enough wool) wherever possible, especially in avoid condensation and mold growth, wall clearance to enable cleaning kitchens and other food preparation and should be smooth, fire-resistant, around the entry point. Flexible fit- and storage areas; and light colored, coved at wall joints, and tings are recommended for gas fit- • Eliminate dead spaces inside storage easy to clean. tings. All electrical switches should areas to restrict areas where rodents be flush-fitting.

12 CASBO JOURNAL JULY/AUGUST 2005 Doors Outside Walls and Building • Use gravel to discourage burrowing. Exclusion Perimeters Where feasible and inaccessible to stu- • Ensure that doors are properly Exclusion dents, maintain a two-foot pea gravel installed and correct problems that • Do not install exterior features that strip around buildings to prevent interfere with a close fit; attract insects, rodents, birds or other rodent burrowing; • Ensure that roll-up or overhead doors wildlife. Avoid installation (particular- • Install guards on pipes and down- are well fitted. With the door closed, ly near entrances) of the following: spouts. Standard conical or rectangu- check for gaps along the sides, bot- – light fixture designs that may pro- lar metal rat guards should be fitted to tom, and top of the door. A gap at the vide opportunities for bird perch- soil pipes and rainwater downspouts, top is common; ing, roosting or nesting; projecting about nine inches from the • Use self-closing doors. All doors – decorative lattices or other struc- pipes and built into the walls at the should close on a level threshold, have tural features that may inadver- point where they touch it. Fit tops of smooth, non-absorbent surfaces, be tently serve as bird roosts, over open pipes with balloon guards. Mesh tight fitting and self-closing; entrances to food services facili- fitted over rainwater downspouts will • Select door styles for ease of mainte- ties; and keep out nest debris; nance and durability. Many food – structural features that provide • Design exteriors that have no access factories use polypropylene or opportunities for rodent harbor- to wall cavities. To protect against toughened rubber doors for ease of age or burrowing. Install bird- mice, no external or other cavity wall maintenance; proof barriers (e.g., netting) that should have any holes larger than • Correct mail slot/letter plates that are are designed to prevent both one-quarter inch in diameter; not at least 30 inches above ground pigeon and sparrow access to pre- • Install fitted grills (small mesh) over level to prevent them from becoming ferred nesting sites. air intakes; and ‘rat flaps;’ • Use enclosed fire escapes to eliminate • Consider pest management when • Avoid the use of door frames with bird perching, roosting and nesting, landscaping near structures. acute angles; and access for other pests; Exterior Siding • Use woodwork that is well-seasoned, • Use durable pest-resistant construc- Exclusion properly-knotted, stopped, primed, tion materials. Buildings are con- • Avoid gaps at edges and corners. and given three coats of polyurethane structed from types of materials and paint; design methods that vary greatly in Facilitate inspection and maintenance • Modify conventional doors. External the degree of susceptibility to pest • Allow clearance for inspection between doors should be fitted with metal infestation (for example, metal and siding and soil surface in order to pro- kick-plates not less than one foot high concrete versus wood). Most struc- vide access to inspect for termite infes- and the metal plates should also fit tures eventually become less pest- tation, and to prohibit exterior siding jambs and door linings; and resistant due to deterioration, contact with soil; clearance between • Use nylon bristle stripdoor sweeps; alteration, or lack of repair. Pre-fab- exterior wall coverings (i.e., stucco, sid- these are remarkably versatile for pest- ricated building panels usually pro- ing) and soil on the exterior of a build- resisting conventional doors. vide more opportunity for ing should not be less than six inches. infestation to develop than do solid Moisture management Windows brick or concrete walls; certain parti- • Irrigation/sprinkler systems and risers Exclusion tion or cladding materials such as for spray heads should have sprinkler • Install close-fitting windows and chipboard, hardboard or blockboard heads or be located two feet from screens. Screens on windows, crawl offer little resistance to gnawing building so as to prevent water con- spaces, and vents are often damaged rodents and may, especially if damp, tacting walls; including drought toler- in school buildings. Check these care- encourage molds, booklice and fun- ant plants in landscape plans can aid fully for needed repair or replacement; gus beetles; in achieving this goal. • Slope window ledges. Window ledges • Avoid rough finishes that can be Roof Assembly or other essential projections should gnawed or provide foothold. Rats and slope at 45 degrees to discourage mice will climb up rough exterior Exclusion birds from perching and roosting on surfaces so it is best to eliminate such • Eliminate rodent access under shin- them; and finishes and to avoid projections or gles; • Modify windows to prevent harborage ledges which might give a foothold or • Build tight roof joints and protect and access for pests, with no clear pas- provide access to any higher points of with flashing; sageways to inside. Modify weep holes entry that are unlikely to be as well • Fit eave roof tiles with bird stops (that (openings that allow drainage of mois- proofed as those on the ground floor; will also exclude bats, bees and ture) in window frames (e.g., with cop- • Screen or otherwise eliminate animal wasps); and per or bronze wool) to prevent access access under decks, porches, and stair- • Make sure all attic and soffit vents are by paper wasps and other insects. ways; properly screened to exclude insects,

CASBO JOURNAL JULY/AUGUST 2005 13 birds, and other animals. Use one- or trash is stored. When stored Sewell Simmons is an environmental quarter inch hardware cloth screen together, these materials put food and research scientist with Cal/EPA’s Depart- mesh (coordinate with mechanical shelter together, favoring pests. ment of Pesticide Regulation. For a list of requirements). Sanitation references, please contact the author at Moisture management • Place outdoor garbage containers, [email protected]. • Direct water from drainage and sprin- dumpsters, and compactors on hard, klers away from walls. cleanable surfaces; and • Include a water source at the site for Refuse and Recycling Areas cleaning permanent storage containers Exclusion and pad surfaces; ensure adequate • Locate site away from building drainage. entrances (at least 50 feet from door- ways); Vertical Shafts • Design site with properly graded con- (stairwells, elevator shafts, dumb crete or asphalt pads to help prevent waiters and refuse chutes) rats from establishing burrows Exclusion beneath them; • Floor cavities should be sealed where • Build to exclude vertebrates. Build they enter shafts or chutes. refuse sites with a solid enclosure that Facilitate sanitation/harborage extends all the way to the ground. Use reduction metal or synthetic materials, as opposed • Shafts or chutes should be of smooth to chain-link or wood, to prevent internal construction. To the extent fea- rodents and other wildlife from gnaw- sible, build or modify these areas (e.g., ing or climbing the enclosure; and use coving at floor to wall junctures, or • Close off refuse, recycling, and trash other means of minimizing corners and storage areas. Locate storage areas for sharp angles) to reduce debris accumu- boxes, paper supplies, and other mate- lation and to facilitate cleaning. ■ rials in areas separate from where food

14 CASBO JOURNAL JULY/AUGUST 2005