How to find and seal roof rat entry points

Updated October 1, 2026. By the OakTend team.

Walk around and over the outside of the house looking for the small openings roof rats use to get into attics and walls, then close them with materials rats cannot chew through.

How often: Once a year, and after any roof, vent, solar or cable work that may have opened a gap.
What you need: Flashlight, Galvanized hardware cloth, 1/2 inch mesh, Tin snips and work gloves, Steel wool or sheet metal for small gaps, Pruning saw

Why it matters

UC's pest program says roof rats favor warm, coastal climates, and the Orange County Mosquito and Vector Control District says they travel neighborhoods along utility lines and fence tops. Sealing entry points is one of the main things the district asks homeowners to do.

Steps

At dusk, watch fence tops and utility lines near the house for rats on the move.
In daylight, check the roofline, eaves, attic vents and where the roof meets the walls for gaps and torn screens.
Check where pipes, wires, cables and AC lines go through the walls.
Seal any opening larger than 1/4 inch with steel wool, wire screen or sheet metal.
Cover vents with 1/2 inch galvanized hardware cloth. Skip chicken wire; rats get through it.
Prune tree limbs to at least 3 feet from the roof, and pull vines off the walls.
Bring pet food in at night and keep birdseed and fallen fruit picked up.

When to call a pro

Call a pest control company if you hear scratching in the attic or find droppings inside. The Orange County Mosquito and Vector Control District also answers questions about rats and can tell you what it offers in your area.

Safety

Do not sweep or vacuum droppings. The CDC says to wear rubber or plastic gloves, soak them with a mix of 1 1/2 cups of bleach in a gallon of water (or an EPA-registered disinfectant) for 5 minutes, then wipe them up.

Go deeper

Termites in Orange County

General information, not professional advice. Your equipment's manual comes first when it says something different.

Sources

UC IPM Pest Notes: Rats (updated June 2025)
Roof rats prefer warm and coastal climates; seal openings larger than 1/4 inch with steel wool, wire screen or sheet metal; use 1/2 inch galvanized mesh on vents, not chicken wire; prune limbs within 3 feet of a roof; rats travel utility lines and fence tops at dusk.
Orange County Mosquito and Vector Control District: rats
Roof rats use utility lines and fences to move around; identify and seal entry points.
CDC: how to clean up after rodents
Do not sweep or vacuum droppings; wear rubber or plastic gloves; 1.5 cups of bleach per gallon of water; soak for 5 minutes.