How to Eliminate Mice From Your Home's Ductwork

A mouse eating crumbs in a dark space.
  • 1-2 hours
  • Beginner
  • 10-20
What You'll Need
Mouse traps
Peanut butter
What You'll Need
Mouse traps
Peanut butter

You hear the gnawing noises. You see the droppings. Occasionally, you see a flurry as one scurries by. When you have mice in the house, it’s time to get out the traps. Effectively placed, traps can help immensely in your effort to ward off the invaders. But mice like to find a safe place to bed down and store their food. Unfortunately, that is often in the ductwork of your house. When the little rodents take up residence in the ducts of your home, it can be annoying, frustrating, and even deadly. Here’s how to tackle the issue.

Step 1 - Investigate

A man standing on a ladder looking at the roof of a brick house.

Finding where the little critters are entering your house is the key to eliminating the problem long-term. Besides, it doesn’t do much good to eradicate them inside the house if they still have access elsewhere.

Begin by walking the perimeter of the house. Look for any entry point along the foundation and all the way up to the roofline, under the decking, through openings in a doorway, near the chimney, or in any other visible gap. Small mice can fit through a space not much larger than a pencil eraser, so careful inspection is required. For example, if the sweep at the bottom of your garage door is uncentered or worn out, there may be a gap in one corner. If you have a gap where your cement sections meet in the middle of your garage, that may leave a space under the main door, as well.

Also look for droppings and the sight or smell of urine. When they begin to use the same route frequently, waste will build up, making it obvious where they’ve been entering. One way they get in is through spaces between the metal sheeting around the furnace—so check there.

Examine beneath your home. Shine a flashlight across the surface of the plastic beneath your home, looking for dropping or footprints in the dust. Entering from underneath the house, they often gain access through tubing if it has a tear or if they chew through it.

Step 2 - Prepare

In order to tackle the problem, you will need a few supplies. There are many, many products on the market from rodent motels to sticky pads, but the most effective product is the good old-fashioned wooden mouse traps. While observing your options in the pest aisle at the hardware store, you may also notice there are baits and attractants available. The product recommended most frequently, however, is peanut butter.

This is because it's sticky and it also requires them to work at it a bit, leaving them as a target for a longer period and increasing the chances of them setting off the trap. Whatever, you do, do not use poison in your ductwork. Not only does it make the poison airborne in your house, but when a mouse is poisoned it will die later, likely deep in your ductwork, which exudes a nasty smell while they decay.

In addition to gathering supplies, you will want to turn off your furnace.

Step 3 - Set Traps

A vent register in wood flooring.

Locate all of your heat registers. In two-story houses, they are often in the ground on the lower level and in the ceiling in the upper level. Set traps using the directions on the packaging. Remove each register and place a set trap inside. Proper placement of the trap is essential. Mice have fine whiskers that run the length of their bodies. They stay near the wall and use those hairs as a guide. Because of this, you want to place your traps perpendicular to the wall with the baited end against the wall.

Step 4 - Check Traps

Check your traps daily. You may be able to shine a light through the grate to see if there is a mouse in the trap without removing each register. If there is a mouse in the trap, wear gloves to remove it, reset the trap, and wash your hands thoroughly.

Step 5 - Call the Professionals

Because mice like to seek refuge in the safety of ductwork, they may have accumulated a food store somewhere in the system. In addition, mouse feces, when disturbed by air, can release the hantavirus directly into your family’s air supply. The hantavirus can cause severe health issues and can even be fatal.

If you've noticed significant rodent activity in your ductwork, you’ll want to call a company that specializes in cleaning out ductwork. These companies come to your home with a truck equipped to suck out all of your ductwork. In addition, they use a high-pressure hose to force air through the ductwork from every air vent as well as the return registers to ensure the entire system is clean.

Mice are not only loud, sneaky, and annoying, but they can also create a severe health hazard within your home, especially when they target your air system. There is generally no need to call an exterminator if you can locate where they are entering the home and set your own traps.