The real problem with chipmunks are their burrows. They are notorious for making deep burrows that are many feet in length. They create a clean sleeping quarter and then numerous side-tunnels for waste and for storing food. That ends up creating quite a network of tunnels and weakened ground right under your house.
If chipmunks become too numerous, you could end up with damaged decks, porches and other yard structures. These can become very expensive to repair. Chipmunks that get into homes and garages can cause even more damage.
Chipmunks are small striped rodents of the family Sciuridae. Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia. Chipmunks may be classified either as a single genus, Tamias, or as three genera: Tamias of which the eastern chipmunk (T. striatus) is the only living member; Eutamias, of which the Siberian chipmunk (E. sibiricus) is the only living member; and Neotamias, which includes the 23 remaining, mostly western, species. These classifications were treated as subgenera due to the chipmunks' morphological similarities. As a result, most taxonomies over the twentieth century have placed the chipmunks into a single genus.