[CaptT820]

Really the only way to keep rodents out is not rocket science, but modern science. As others have said, don't allow them in, in the first place. If building new, seal literally every possible crack, opening, or hole with silicone, great stuff, or some other chemical sealant. Rodents do not like spray foam as it is toxic to them. If placing insulation use roxul, spray foam, or some type of cellulose insulation that small critters don't like. Fiberglass is like a winter condo for mice and will never keep them out. Cellulose is slightly more money, but is rodent proof, and gives a greater insulating value per inch than fiberglass.