Raccoons can enter a house through any gaps or openings. They scratch and chew at any viable hole they find until it is big enough for them to pass through. Apertures along the roof and dog or cat doors are some of the most common points of entry.
While garbage bins filled with food scraps are attractive places for raccoons to commonly forage in, they will still try to find a way into homes to seek safe shelter. Some people may find these creatures cute, but they can also cause harm and harassment to residents.