Cockroaches get into houses primarily through small cracks and crevices in the building structure, plumbing and drainage systems, vents, and gaps around windows and doors. They can also hitch a ride on bags, luggage, secondhand appliances, grocery bags, and boxes. In multi-unit buildings, they can travel through shared walls, pipes, and electrical conduits. Cockroaches are adept at squeezing through tiny openings as narrow as 1/16 inch wide, making even small gaps an entry point. They are attracted to food, moisture, and shelter inside homes, so areas like kitchens, bathrooms, and basements are common places they target for entry and habitation. Preventative measures include sealing cracks, fixing leaks, covering vents properly, minimizing cardboard storage, and inspecting items brought into the home.