One question we hear a lot from homeowners is “How are these mice even getting in my house?!”

While every home is different, there are several common areas that lend to easy rodent access. The best way to get a comprehensive understanding of your home’s vulnerabilities is to have a pest professional assess your property, but here are a few things to look for:

Rodent Sized Gap Where Utility Lines Enter Structure

1. Rodent Entry Around Utility Inlets:

When utilities are installed on a new or pre-existing structure, lines are typically run into the home by cutting or drilling a hole through the wall. Often these openings are slightly larger than the line being run into the home which leaves a spot for mice to enter the structure. Ideally these gaps would be sealed by the installer, but they are often overlooked or the sealant deteriorates with age.

2. Rodent Entry Along Foundation Sill Plate:

In construction the sill plate is the part of the structure where the horizontal foundation/wall meets the vertical joists. When a home is built on a concrete foundation, the top of the wall is not always level so shims are used at tie down points to level out the wooden framing. This shimming can create gaps that rodents use to enter a home.

Rodent Hole in Flashing in Soffit

3. Rodent Entry at Soffit Roof-line Intersections:

For the purpose of this article, soffit roof-line intersections are areas where two roof lines meet creating a protected overhang. Builders and roofers do not always seal or flash these intersections appropriately because they are typically not high water areas. Sometimes the flashing is not even present, but often it is not installed securely or rodents are able to chew through the material used. When this happens, animals and rodents are able to take advantage of the gap to enter attic spaces or wall cavities.

Gap That Allows Rodent Access Under Garage Door Bottom Seal

4. Rodent Access Around Garage Door Seals & Jambs:

The side frame that supports the garage door track is called the garage door jamb and sometimes it does not extend down to the concrete floor leaving a gap for rodents to enter. Settling of the concrete can further exaggerate the gap or cause the mortar that used to seal the area to fall away. Garage door seals can also deteriorate over time allowing rodent access. Often we find that the side or bottom seal has frayed or been cut too short and rodents can go under or around them. Settling of the concrete can also cause an issue where the bottom seal does not fit tightly across the entire span. These issues can often be remedied using custom seals and minor door adjustments.

Cantilever Without the Bottom Sealed Allowing Rodent Access

5. Rodent Entry Under Cantilevers:

Cantilevers are parts of a structure that extend horizontally past the foundation wall. In Colorado, cantilevers are often used for fireplaces, kitchens, and bay windows. Some cantilevers are very close to the grade/ground while others are a foot or more up the side of the exterior wall. Cantilevers become a problem when the bottom is not sealed properly.

In some cases, a board was never installed to seal off the joists and rodents can enter the floor space freely. Other times a board was installed, but it was not sealed or fastened properly leaving gaps for mice and other animals to enter. Still other times, the bottom of the cantilever is sealed with wood that is not rated for ground contact and/or moisture and so it deteriorates. This allows rodents to chew through the deteriorating wood to enter the structure.


If you identify any of these problem areas on your property, it may be time to get professional assistance with repairs. Don’t forget that it is important to get a quality repair from a provider with knowledge in both the construction and pest management arena. And ALWAYS avoid repairs that employ spray foam or steel wool as rodents are known to chew through both.