The best rodent prevention method is keeping your building’s exterior sealed. Inspecting it regularly and sealing any cracks, holes, or other kinds of damage that rodents could get inside through is crucial. Keeping your environment clean by taking out the trash regularly, sealing garbage cans, and putting away food is also a great way of discouraging rats from entering your space. Most sound-based and many scent-based repellants don’t really affect or prevent rat problems.