Prevention
for Norway Rat
Exclusion is the most durable defense — "build them out." Seal any opening larger than 1/4 inch, which closes gaps to both rats and mice: foundation cracks and the gaps around pipes, wires, drains, and vents. Fit doors, windows, and screens tightly, capping chew-prone edges with sheet metal where gnawing occurs. Pair sealing with sanitation — store food and pet food in rodent-proof containers, and clear woodpiles, rubbish, and dense ground cover that shelter burrows. Source: https://ipm.ucanr.edu/home-and-landscape/rats/pest-notes/