Our tenant’s Christmas cooking party turned out to be a stinker when mice took up residence in the back of the gas oven. Building Science informs us that heating accelerates chemical reactions. Imagine Old Dog Smell to the 10th power.
Cleaning did not change the smell factor. Here’s the sexed-up explanation why: http://www.salon.com/2012/11/03/chances_are_your_house_is_soaked_in_mouse_urine/
Animals obey their biological imperatives. They’re adapted to survive. They seek shelter from the weather and predators, warmth and moisture, they eat, procreate, nest, poop and piss, defend and expand their territories. I have 30 years first-hand experience with un-invited guests, human and otherwise.
Rats run alongside exterior walls, seek cover and burrow under foundations. They climb trees and run gutters until they find gaps between the fascia and roof. If there are no gaps they’ll gnaw through water-weakened wood. Rats chew through rubber and plastic pipe to get a drink. They thrive in wet basements and crawl spaces. They love grass seed. They favor the warmth atop water heaters, furnaces, ductwork and the tops of ceiling tiles in basements. They nest in attics, in ribbed plastic ductwork, in cluttered crawl spaces and basements and in walls.
Chipmunks (ground squirrels) burrow near foundations. Burrows channel water toward foundation walls and provide ready-made invasion routes for rats. Flying squirrels are the octopi of the rodent world. They squeeze through the smallest of openings and nest in quiet attic spaces. Mice live in hollows of walls and ceilings….. and in ovens. Gray squirrels prefer attics. Squirreled-away nuts are a sure sign of activity. They’ll also nest in uncovered chimneys. Nesting squirrels filled our 25 ft chimney flue with tree branches.
Other Warm and Cold Blooded Creatures
Bats prefer warm south or west-facing attic gable vents. Nesting birds also use gable vents-they often pile nesting materials several feet deep. Opossums and Raccoons nest in attics and uncovered masonry chimneys. Rat snakes take up residence where there is sufficient prey. Bears, coyotes and raccoons will get into the trash or compost. House Wrens Nest near and in houses. http://www.nps.gov/nr/travel/atlanta/har.htm
Health, Safety and Functional Concerns
The Power of Piss triggers asthma attacks. Animals and their feces may transmit diseases due to parasites, bacteria and fungi. Bats are known carriers of Rabies (about 5%). Never handle a bat bare-handed. Rodents chew through wiring insulation to mark escape routes causing an increased risk of fire. Animal bites are bacterial bombs and should be dealt with immediately.
Animals tramp down, pull apart and disturb wall and ceiling insulation-their preferred nesting material reducing insulation effectiveness.
What Homeowners Can Do
Step 1. Knowledge is Pest Control Power
Pests are ever-present and live just beyond our field of vision. Animals are biologically engineered to survive. They possess highly developed senses the and ability to detect variations in pressure and moisture.
The hollows of framed walls and between floors, flues, ducts, plumbing vents and wiring openings, are their vertical and horizontal paths through homes. They inhabit spaces behind kitchen appliances, behind and under countertops and cabinets, in pantries and dropped soffits (ceilings); wherever there’s room to hide and store food.
Buffered Zones like attics, basements, crawl spaces and storage areas, especially wet and cluttered ones, are ideal because they are close to sources of food and provide shelter, moisture and warmth.
Step 2. Discourage pests by making your home less hospitable for them:
Outside the House
Screen and seal openings in exterior walls at crawl vents and other wall penetrations. Use hardware cloth, a galvanized mesh with 1/4″ openings, and foam sealant. Trim tree limbs and shrubs away from outside walls and roof. Move or trim plants away from exterior walls. Replace vegetative ground cover close to exterior walls with gravel. In all ways and as much as possible reduce the volume of roof and site water near exterior walls. Clean gutters and grade or drain roof, surface and A/C water toward the downhill side of your home. Store birdseed, grass seed and other rodent foods in sealed containers. Bird feeders are favored in the daytime by chipmunks and squirrels, at night by rats, mice and opossums.
If you leave pet food outside expect it to be eaten.
Exterior and Attics
Screen and seal outside openings: at soffit vents, gable vents, at corners, where the fascia and gutter meet, at plumbing vents, at roof exhaust vents. Draftstop (method of sealing with rigid materials) openings that connect the attic to the house: at plumbing, ducting and wiring openings penetrations. This will also limit the movement of fire and loss of conditioned air.
Basements and Crawl Spaces
Consider closed and conditioned crawl space design: http://www.crawlspaces.org/
Install dehumidifiers in un-ventilated areas to reduce moisture. Set glue traps for mice, spring traps baited with peanut butter for rats. If all else fails install a concrete rat slab over crawl space soils. Draftstop openings at plumbing drains and vents and where A/C lines and dryer vents extend to the outside. Install hardware cloth over crawl vents. It’s especially important to clean up crawl spaces: remove clutter and debris and cover soils with plastic.
Inside the home
Remove clutter in kitchens, closets and storage areas. Fix plumbing and roof leaks. Keep a clean kitchen. Use covered trash containers. If your heating vents are in the floor vacuum them out-especially in the kitchen. Check for evidence of infestation at or behind fixtures and appliances, especially in kitchens and bathrooms.
Contact a qualified pest control company. If pests are a big problem plan for multiple visits.
Expect repeats. And don’t ignore the Power of Piss.