ᐅ Why are mice not an issue with cavity walls?

Hello,
we are just at the very beginning of our building planning and are currently doing a lot of reading. One question, for which I have not found any information so far, is the following: Why are mice not considered a problem in a cavity wall construction (with a 2-6cm (1-2.5 inches) air gap) – at least this is never discussed anywhere? Is it assumed that the layers will remain completely sealed for the next fifty years? Or is it not an issue for the insulation between the layers if a large population moves in there?
Karl

If you have enough cats, there will generally be fewer problems with mice. However, this can vary from year to year and depends on the location of the house.

In principle, there are always recurring issues with animal infestations in cavity wall insulation. A mouse can slip through an opening smaller than 5mm (0.2 inches). Insulation cavities are usually not sealed that tightly. Since mice are also attracted to the cozy warmth of mineral wool insulation, problems can arise depending on the population size.

Once mice have gotten into the insulation, it becomes very difficult to remove them.

Try searching online for mice in prefabricated houses, there are plenty of results.
Then look up ants in prefabricated houses.

Thank you very much for the quick responses. With the keyword "joint ventilation," I was now able to find quite a bit of information. Apparently, it is indeed a problem, even in new buildings with cavity wall construction. The solution seems to be joint ventilation grids (and, of course, otherwise airtight masonry).

Thank you again.

Karl

karl.jonas schrieb:

double-shell wall construction (with 2-6cm (1-2.5 inches) air gap)

Why an air gap? If you decide, for whatever reason, to install an air gap, there are very small ventilation slots that can also be sealed to prevent pest infiltration.

karl.jonas schrieb:

Are we assuming that the shells will remain completely airtight for the next fifty years?

Just as airtight as the masonry. So yes.

No air gap = no openings whatsoever = absolutely no pests inside

@Benutzer200: After your (presumably rhetorical) question, I naturally searched online and found an article by Helmut Künzel titled "Double-Skin Masonry: With or Without Ventilation" (Fraunhofer IBP). His conclusion is: "A fully insulated cavity is unproblematic and provides optimal thermal protection with the given construction dimensions."
karl.jonas