""By Dr. Gerry Wegner, BCE

To view this article as it appeared in PCT magazine, please click here.

Every now and then, we get calls from folks who are quite certain some kind of animal is in their residence because they can hear noise in a wall, ceiling or attic. But when we send an associate over to perform an inspection, no evidence of rodents or invasive wildlife can be found.

Upon further investigation, and sometimes several visits later, other sources are revealed to be responsible for suspicious noises — sources that have nothing to do with the pitter-patter of little feet or gnawing of structural elements by tiny mandibles. Here are a few “A-ha!” moments we’ve had over the years.

Those Pesky…Trees? Perhaps the simplest explanation for scratching sounds from exterior walls and attics is the rubbing of tree branches against siding or roofing when the wind blows. Always carefully check the proximity of trees to buildings. We recommend pruning branches near walls or roofing to allow a space of 8-to-12 feet from exterior structural surfaces. Of course, this also prevents animals from bridging onto residences from trees in the future, solving a real potential pest problem (in addition to getting rid of the noise). It may seem like a lot of distance to a client, but reassure them that it really is the best way to protect the home from real (and imagined) pest threats.

Trees also can be responsible for “plinking” sounds overhead. A stiff breeze can cause nut-bearing or oak trees shadowing a residence to lose acorns and nuts from their twigs, occasionally striking the house. Another breeze-related sound can be caused by the swaying and tugging of above-ground cables, wires and satellite dishes that attach to siding and rooflines of homes. These sounds may be alleviated by having the attachment and penetration points checked by a cable technician or electrician to make any repairs or adjustments.

Outside Animals. Of course, sometimes wildlife is responsible for the sounds being heard indoors, but not as a result of activity inside walls or attics. Because of the way homes are constructed, even small sounds can be conducted from exterior surfaces to interior areas, making it seem like the sources are close by.

For example, a bird rubbing its beak on a rain gutter might sound like something tapping inside the upper wall or attic. Likewise, a squirrel or raccoon scurrying across the roof could sound like it was running through the attic. Careful inspection of the interior and exterior of the residence will quickly reveal whether or not wildlife or mice have been active, and the cause of these unexplained noises.

Just the Pipes.
 A repetitive ticking or clicking sound coming from walls and ceilings can result from the expansion and contraction of metal HVAC ductwork that conducts ventilation through these voids. When metal heats up, it expands; when the furnace stops pushing warm air through the system, the metal cools and contracts. Similarly, a water heater can make a ticking sound while warming its contents. This sound can be conducted along the copper pipes that run up and out through walls. We have had people swear to us that an animal is responsible for such sounds. As pest management professionals, there’s not much we can do to eliminate these sounds, but educating and reassuring clients is a service in and of itself, without actual pest control being performed.

What’s that Sound? Perhaps the most frustrating thing about all these situations is that everyone involved — residents and PMPs — must be present while the noise is being produced. It can be a major challenge getting everyone to agree about whether or not an animal is responsible for the sounds, but calmly explaining the rational cause in your position as the consultative expert is the best approach. Even if you have to return to the house for a follow-up visit, ensuring that your clients feel heard is as important as solving a real-life pest problem when it comes to building and maintaining a relationship of trust and respect with your clients. Thankfully, we have found that in most cases, the “A-ha!” moments are shared, and peace of mind is restored. In the end, that’s what we strive for.


The author is technical director of ProGuard Commercial Pest Solutions, Columbus, Ohio. He can be reached at gwegner@giemedia.com.