Discovering that you have rats can be an unsettling realization. A rat infestation in the crawlspaces underneath your house can be a potential health hazard, as wild rats often carry many diseases capable of being transferred to humans they share space with. Exterminators can take care of your rats, however they are often quite expensive. Solving your rat problem for yourself is another, more cost-effective option.
Locate where the rats gained access to your crawlspace, and any areas through which they can then access your house. A rat needs less than an inch of space to squeeze into an area.
Seal any gaps the rats may be squeezing through. Caulk gaps in windows that are improperly sealed, and board over or re-cement any holes in your house's exterior or foundation that could be used to access the ground under your house.
Place snap traps in the areas the rats are infesting without arming them, and leave them there for several days. Rats are wary of change, and this will allow them to grow accustomed to the traps.
Remove the traps, and bait with peanut butter before returning them to their positions, and leaving them to catch the rats.
Dispose of any rats caught in the traps. Take the rats immediately to an outdoor garbage to avoid the spread of diseases the rats may have.
Clean the areas the rats had infested thoroughly. Remove all droppings, and scrub down any surfaces the rats frequented.