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Sealing Up the Home – Where To Look For Gaps and Holes

We oftentimes get calls from homeowners who have just found a mouse in their newly built home. Frequently, they are upset with the builder for not building their home correctly. It is important to understand that new or old, all homes have potential entry points for mice. Here are the important points you need to know regarding sealing up the home – where to look for gaps and holes.

Outside or Inside?

If you are wondering whether you should start sealing holes from the inside of the home or the outside, the answer is a little more complex than either-or. The best approach is to connect the dots between the activity on the inside and the outside. This will determine what needs sealed up or blocked off.

If rodent activity started in the kitchen, pay attention to plumbing, wiring, and ductwork. It is unlikely that a mouse is going to bore straight through a 2×4 to gain entry. Rodents are accustomed to following lines such as branches. Plumbing and wiring look just like a path to food.

Once you have a good idea of where those items go, head outside and check in the areas that correspond to that portion of the home. It doesn’t always align clearly, but there is always a connection.

Common Culprits

While every house is different, there are certain areas that are a higher likelihood of allowing entry. If you don’t know where to check, start with the following list:

image of a window

  • Wires going in and out of the home from the outside
  • Piping going into the home from the outside (e.g. a/c unit conduits)
  • Windows & Doors – especially weatherstripping
  • Seams – the foundation to siding, chimney to home, etc.
  • Covered portions of the home – bay windows, low decks, porches, etc.

image of a window

As you look over these things, look from above, the side and below. Rodents have a different perspective than we do. Utilizing a reflective mirror may make this process easier. Look for gaps 1/4″ or larger. Mice are very flexible and can pull off maneuvers that put our best human contortionists to shame. Don’t forget to press on areas and see if they are soft or malleable.

Light Test

Once you are finished with the external inspection, you can head inside to shed some light on the subject. The idea is to find areas that you can completely darken and look for light coming in where it shouldn’t i.e. not through a window. This works well in furnace rooms, unfinished basements, garages, etc. The darker you can make it, the better. If you see light, you can dive deeper into that area.

Draft Test

Similar to the light test, you can use other external elements as indicators of where things may be getting in our out. This is best done on a cold winter day when the temperature differential between inside and outside is significant. Simply put your hand close to the wall working high, medium, and low checking for cold spots. In some cases, it may help to moisten the hand doing the checking to accentuate the difference. If you feel a draft, dive into it and see what is going on.

Patch It, Caulk It, or Stuff It

Once you find where mice are getting in, get an immediate fix in place. You can use patches, repair weatherstripping, caulk it, expanding foam, or stuff in rodent proofing materials. Be aware of the exposure and elements that will come in contact with the rodent proofing materials. Select the right material for the situation.

One common mistake people make is they select something such as steel wool to stuff in a hole. It will work well for a while, but once it gets exposed to moisture for a while, it rusts, corrodes, and falls apart. Not only does this fail to keep mice out, but it can leave an unsightly mess.

After you get a temporary fix in place, see what is the best option for a permanent fix. If the supporting board under the window is rotting away, don’t keep stuffing things in the next hole; just replace the board.

Help is Available

The rodent exclusion process can be quite a battle. If you are frustrated with it or simply don’t want to tackle it, turn to the experts at Rove Pest Control. Mice will shift and adjust their strategy – especially if one of their entryways is taken away. Get help along the way or turn the entire project over at .