Depending how big the opening you could use Pur Black Foam, Xcluder or Copper Mesh to seal off the area after getting rid of the infestation. We have a number of Rodent Exclusion Products here. Here is a step by step guide to rodent proofing your home: Inspect foundation all the way around the home. Any crack, gap or hole that is ¼” or larger needs to be repaired. In holes that are 2” or smaller, Stuf-Fit Copper Mesh, Xcluder Single Roll or Pur Black Foam can be used. In larger holes or gaps you may need to use sheet metal or hardware cloth with less than ¼” mesh to repair the area. Check all doors, door frames, windows and window frames. Replace any weather stripping that does not create a tight seal. Replace any broken window panes. Replace any damaged window or door screens. Repair any gap, hole or crack around frames that are ¼” or larger. If gnawing damage is present on doors, a metal kickplate should be installed to prevent any additional gnawing. Inspect all trees and hedges near home. Any tree branches or hedges that touch or hang over the house should be cut back to prevent rodent from using them as pathways onto and into the house. Keep grass short and trim bottom of hedges or bushes to expose soil beneath and eliminate rodent harborage areas. Inspect the roof. Check shingles, roof ventilators and vent screens to be sure they are secure and undamaged, replacing or repairing as needed. Make sure the chimney is capped to prevent animal entry. Look at all utility entry points. Areas where utilities enter the home can also make easy access points for rodents. Make sure any gap or hole larger than ¼” around the wire, cable or pipe is sealed using Stuf-Fit Copper Mesh, Pur Black Foam, Xcluder, hardware cloth and mortar or sheet metal where needed. Pipes that run vertically up houses can be utilized by rats as direct pathways onto and into your home. You can paint a 12” band around the pipe at least 3 feet from the ground using high gloss clear paint to stop rodents from climbing. As an alternative you can place circular metal rodent guards around the pipe. Brick or stone houses can be very easy for rats to climb. As with pipes, you can paint a 12” band (at least 3 feet from the ground) using high gloss paint all the way around the structure to deter climbing. Remove food and water sources when possible. Feed pets in the morning and remove any uneaten food immediately. Find and fix any leaking pipes or drains. Remove bird feeders if possible to eliminate the bird seed as a possible food source. Clean up any rodent feces and urine found during the inspection. Be sure to wear protective gloves and a respirator to avoid breathing in any fecal matter. Use a bleach solution to clean rodent nesting areas and entry points to get rid of any pheromones left behind that may attract future rodents.