You read alot about how you have to mouse proof your home to keep mice out so they don't become a problem. This fact is true. The question becomes; what can resist the sharp fangs of a rat and mouse? The incisors of a mouse are able to chew through cinder block, bricks, soft metal. It is obvious these rodents are resourceful when it come to the art of chewing. So what makes all these experts think that stuffing a hole with cement or "stuf-fit" or foam will keep out these mice with razor sharp fangs? Simple. Mice can be just as lazy as you and me. They would just as soon take the path of least resistance then chew through foam. If there is a hole that is open they will go through it, if it is stuffed they will move onto an easier entrance. So look for these holes a fill them in. You will give yourself a ninety percent head start in keeping mice out. Mouse proof to your hearts content. Build those suckers out, and you will thank yourself later.