Inspection Unit 4B

Prevention and Species

Prevention Part 2

This section covers how to help your clients prevent future animal damage. Whether the customer has suffered animal damage or not, ethical inspectors educate clients about how to reduce the property’s attractiveness to home seeking animals.

(All photos on this page are by Stephen M. Vantassel)

Exclusion is the last strategy to reduce animal entry onto your property. The first step in exclusion is by keeping your house and buildings in excellent repair. Animals are exploitive; if they find a weak shingle or rotted wood, they will claw their way through those materials to live in your warm attic. Keep in mind how attractive your house is to an animal. It has many advantages over a tree in that its warm, insulated, dry, and doesn’t sway when the wind blows.

Screen on vinyl attic vent.The first area a homeowner should seek to secure is the attic vent. The photo shows screening used on a vinyl siding. Here it is just bent around the screen frame, no screws. (Be careful making holes in siding and anywhere else in the building, as it could encourage water damage). Squirrels often enter buildings by chewing or pushing through the mosquito netting screen that keeps insects out of the attic. Ideally, all attic vents should be secured with ¼-inch wire mesh on the exterior of the building so as to protect the wooden louvers and the mosquito netting. I strongly recommend that the screen be screwed into place at each corner and then stapled securely around the remainder of the perimeter. Quarter-inch wire mesh will protect the attic not only from squirrels, but bats as well. If you are concerned about aesthetics, then secure it on the inside. However, be sure that the mesh is towards the exterior of the building so as to protect the mosquito netting from potential damage.

All chimney flues should be capped. Capping a chimney flue not only prevents animal entry but it protects the chimney from water damage. Customers usually ignore my advice to cap their chimneys. They just don’t believe that raccoons and squirrels enter chimneys until it happens. Raccoons generally reside in chimneys from March-June to raise young. Squirrels often will be found in basements during the months of Jan/Feb and Oct/Nov because they fall down the furnace flue while looking for a potential nesting site. The cap you have placed on your chimney should be professionally manufactured so as to follow proper venting guidelines.

Do not cap chimney with screening.Don’t use screening to cover a chimney because heavy snow and/or freezing rain may accumulate on the mesh, forcing the gases back into the house. The image shows how NOT to cap a chimney. Photo by Stephen M. Vantassel.

If you cap your furnace flues, I strongly recommend that you obtain a carbon monoxide detector. Oil- and especially gas-burning furnaces exhaust a great deal of moisture as a by-product of combustion. The manufacturers worry that this moisture could freeze on the cap (during extreme cold temperatures) and thereby force the gases back into the house. While not aware of this phenomenon happening anywhere in the U.S., you should be prepared for it. Finally, all caps should be of stainless steel construction.  Although they generally cost about twenty dollars more, they are guaranteed for life against rust and corrosion.

Good trench screen example

Porches, mobile homes, and sheds can be protected from burrowing animals like skunks by constructing appropriate barriers. The best barricade consists of laying a wire mesh skirt perpendicularly away from the wall of the porch. This floor skirt should be 2-3 inches below the soil’s surface and extend out at least 12 inches. Then secure some galvanized ¼-inch or 1/2-inch hardware cloth to the wall and, at the base of the trench, bend it out so that it will extend one foot away from the structure. This type of barrier prevents animals from digging under the structure. No matter how far the animal digs, it will keep meeting mesh. (Photo by Stephen Vantassel is an example of a good trench screen).

Have your client act on these recommendations and the likelihood of the building ever having a problem with wildlife will be greatly reduced. However, should they ever need help in controlling an animal damage problem, be sure they contact a licensed problem animal controller. They are the individuals licensed to handle these situations.

Finally, understand that these are introductory recommendations. Do not consider them complete. Visit to learn more.

©2005 Stephen M. Vantassel

Unit 4C