How to Look for Rat and Mice Entry Points

A thorough inspection of your home is the first step to getting rid of your pesky visitors. There are many things to look for and if you’re in California, chances are most articles you’ve seen online don’t quite seem to fit your home. Because we specialize in rodent exclusion and eradication in California, we’re well versed in the construction techniques used here. Most houses have the same basic few problems plus the one or two more complicated issues. If your eyes are already glossing over and you’d rather spend a few bucks to get the issue fixed (and you’re in the Bay Area), click HERE to book a free inspection.

We use a checklist for our inspections which is key to making sure you don’t forget an area. A proper inspection starts at one corner and goes all the way around the perimeter. Some inspectors like to look around the foundation and lower areas first and then go back around and look at the upper areas, some inspectors like to do it all at once. My recommendation for a homeowner is the latter option. You’d be surprised at how many potential areas rats and mice can find on most homes so looking at the lower section of your house and then the upper is a great way to make sure you’ve seen all the exterior stuff. A quick list of things to look at are: foundation vents, bottoms of side garage doors, bottom and corner of garage door, potential foundation burrowing, under siding/stucco, under decks (may need to hop under your house for this one), pipe penetrations (mostly AC lines in California), exterior subarea access door(s) (if you have a subarea and if it’s accessible from the exterior), under chimney or bay window kick-outs, soffit vents (the vents under your eaves at your roof line), roof returns (where one roof line overlaps another) and gable vents (the vents at the peak of the attic on the side of the house).

When you’re looking at all these things around your house, make sure to look for holes, gaps and importantly rub marks. The holes needed for mice are 1/4” and rats are 1/2”, a quick way to determine this is the pinky - thumb technique. If you can fit your pinky in a hole, that’s roughly the size a mouse needs and if you can stick your thumb in a hole, that’s roughly the size a rat needs. So, we always look to seal pinky sized holes or bigger to be on the safe side (in some cases even smaller holes need to be sealed to prevent them from making those holes bigger).

Rub marks are grease stains left behind from where rats and mice rub over stucco, wood, etc. and leave a dark mark behind, they are also an important thing to look for because these will help you figure out where the rodents are traveling. Almost every article online makes it sound like rub marks will immediately be identifiable and are like a treasure map. Most of the time rub marks are actually a little hard to find (except in rare super-heavy infestations). A trained eye will know where to look and can find them pretty quickly but most homeowners simply don’t know where to look or sometimes even what to look for.

Once you’ve checked out the entire exterior, you’ll need to also check in your attic and your subarea (if you have one). There may be inaccessible areas (like decks) that can only be checked by getting into your subarea. Your attic can also hide some crazy entry points you would never think would be there. Make sure to check the plumbing vents for improper installation going up into the roof, check your roof returns from the inside and check your HVAC ducts that go up to any roof vents - we’ve actually seen them getting in there believe it or not!

If you feel like you can take care of your rodent issue on your own, please do. If you’ve tried everything and it still isn’t helping feel free to reach out!

Here’s some pictures that should help with your inspections.