I’m remodeling a house that was built about 30 years ago. Although this house is in a suburb that has good building codes, those codes have updated during the years.
Currently, all new homes in that suburb require fire stopping. This involves sealing holes between floors, which would prevent mice from traveling from the home’s crawl space to other floors. However, this code was not in effect decades ago. It is common for mice to try to enter warm spaces as the weather cools. If they find a habitable space they may decide to “set up shop” there. Apparently, that is what happened in this home.
The owners were aware that they had a mouse problem. However, now they know where those mice are coming from. I plan to block all access areas in this wall to impede their furry friends. I”ll also use foam insulation which not only has a high R value, but also an excellent “M” repellant value (my term).