Hearing crawling or scratching in your vents typically points to two main culprits: pesky critters or loose, expanding metal ductwork.
Mice and Other Rodents
You may hear them scampering through the metal ductwork, especially at night. Rodents in air ducts can cause damage by chewing on wiring, insulation, and air duct materials. Their nesting materials and droppings can trigger allergies and asthma flare-ups if blown into the home through vents.
The exact cause of the noise from your vent depends on the type of sound. To narrow it down quickly:
An animal in your HVAC ducts is something no Detroit home or business owner wants to deal with. Pests like mice, rats, squirrels, birds and insects can all find their way inside. Once they're in, they can damage ductwork, tear insulation, and cause possible health hazards like allergies and asthma.
Dust mites generally do not live inside your air ducts or vents. They cannot survive in bare metal or fiberglass ductwork because they require high humidity (usually 50% to 80%) and fibrous, accessible food sources like dead human skin cells.
In dust mite allergies, swelling, called inflammation, of the inside of the nose, causes:
How to Tell If It's Mold — Or Just Dirt
Warning Signs Of Having Mice In Your Vents
Identifying an animal in your attic by sound depends on the time of day, the volume/weight, and the type of vocalizations or movement.
As the air in your HVAC system passes through your ducts, it can cause the metal to expand and contract as it heats up and cools down. This can lead to your air ducts making popping sounds or cracking noises that are often louder in certain areas of your home, depending on where the HVAC ducts are located.
Animals, especially rodents, have a tendency to make their way into the air ducts of your homes. They create an entire habitat inside the air ducts, nesting and reproducing. Needless to say, this negatively affects the quality of air conditioning in your home as well as the health of your air quality.
A clogged plumbing vent pipe starves your drain system of necessary airflow, creating a vacuum that disrupts water flow. Common symptoms include gurgling noises in drains after flushing or using water, slowly draining sinks or tubs throughout the house, unpleasant sewer odors indoors, and sluggish, inefficient toilet flushing.
Sanitize and Deodorize Air Ducts: Professional cleaning eliminates droppings, urine, and other contaminants, ensuring clean indoor air quality. Occasionally, an animal will die in your air ducts. The professionals at Trutech can remove the carcass and get rid of the dead animal smell. Avoid DIY removal.
If you are hearing noises in your attic, mice typically produce light, rapid scratching, scampering, and scurrying sounds. Because they are nocturnal, these sounds are usually the loudest at night. You may also hear faint gnawing or crunching sounds as they chew on wood or plastic.
Another common cause is expansion and contraction due to changes in temperature. Oil Canning – When the walls of your air ducts move in and out due to pressure differences, you may hear a rumbling, popping sound.
Yes, someone can live in your attic or hidden crawl spaces without you knowing. This real-life phenomenon, often referred to as "phrogging," involves a stranger secretly taking up residence in an occupied home. Because these intruders aim to go unnoticed, they can remain hidden for weeks or even months.
Roof rats are most active during the warmer months when food is abundant, but they can remain active year-round in milder climates. Cooler weather often drives them indoors, where they forage for food and shelter.
The most common animals in attics are mice, rats, squirrels, and raccoons. Narrow down your unwelcome guest by listening to when the noise happens and what it sounds like:
Vents that are not properly sealed or have loose covers can be an easy access route for mice. Once inside, they can move through your home using the vent system. They are attracted to warm spaces, and vents often provide just that. It's crucial to be aware of this possible access point and take action to secure it.
Here's the reality: if you see one mouse during the day, there are likely 5-10 more you're not seeing. In other words, daytime sightings almost always indicate multiple mice. Even nighttime sightings suggest more than one. Mice are social animals that live in family groups.
Yes, mice will occasionally go near or even climb on sleeping humans. While mice are naturally skittish and prefer to avoid human contact, they are nocturnal, excellent climbers, and fearless when searching for warmth, nesting materials, or crumbs.
Mold toxicity (or mycotoxin illness) occurs when you are exposed to mold spores that produce toxic byproducts. These symptoms can mimic other conditions and often range from mild respiratory irritation to severe neurological and immune responses.
To kill mold in air ducts, you need to use an EPA-registered HVAC disinfectant (like RMR-141) or natural solutions like undiluted white vinegar or 3% hydrogen peroxide. Always spray the solution onto a cloth to wipe hard, non-porous surfaces, and address the root cause of moisture.
In A Nutshell: Misconceptions About Mold
Your home can be 100% mold-free: No, there are always mold spores in the air. Anyone can effectively remove mold: No, you need professional services for that.