First the good news... you wont have any mice! Now the bad news... snakes are magicians and will get in somewhere, somehow. I had 2 blacksnakes living in my basement in rural Pa for years... they (named Helen and George) took up residence on the top of the cinderblock wall above the oil burner... I suppose this was a cozy spot for their home. I found snakeskins in the basement when we did the pre-purchase home inspection... figured they were blacksnakes, which they were, and figured I was lucky to have free mouse extermination for my mountainside home. Gotta admit I was shocked the first time I saw Helen and George slithering toward the house one day when I was outside. Old George was over 5 feet long and fat as my forearm. Helen was leaner but almost as long. We watched to see where they got into the house and the 2 buggers slithered vertically upward over 3 feet to where the siding met the block and squeezed through a space 'bout the size of the key on my computer keybord. All was fine until one day I heard the Mrs exclaim... "that's where I draw the line... " Turns out she was down in the basement and there was ol Helen and George all curled up together in domestic bliss when suddenly a tiny 3rd head pops up and I'm thinking... uh-oh... we got ourselves a family... A case of expansion foam and a few months later our friends were gone.... probably to the neighbors.
I think we can all live together in harmony. Some day I'll tell yall 'bout the nest of timber rattlers in my neighbors window casing.