In order to effectively seal up any points of entry that an animal can gain access to it is important to perform an inspection to determine the points of entry. Rodents do not need much space to gain access into your home. During the winter months, animals seek out shelter to give birth to their young as well as for food and water. Food becomes harder to locate as the colder weather sets in. Rodents such as rats, mice, and squirrels can cause an extensive amount of damage as they can chew through wires and pipes which can cause a fire and extensive water damage costing hundreds if not thousands of dollars in repairs. The insulation can become soiled and damaged due to the rodents use of the insulation for nesting material leaving behind urine and feces that can also pose a health risk for occupants.
There are a few steps that you can take to determine if there are any entry points that need to be sealed. An inspection of the property from the outside should be your first step in determining where the animals may be gaining access. They can gain access into the attic through the tiles, rafters, gables, and soffits, they can also gain access into your home through the chimney, floor drains, windows, floor and dryer vents, holes used to pull wiring through (ex: cable, phone, plumbing, electrical), under sinks, doors, and crawl space vents.
Always consult with a professional. It is not recommended that a seal up be performed by someone who is not knowledgeable in this area as the risk of an animal being trapped in is always a possibility. Before a seal up can be performed, it must be determined that there are no animals left inside and that the materials used for the seal up will prevent the animal from being able to chew its way back in.