Rodents

Preparing Your California Home for Roof Rat Season

When California's first cool rains arrive, roof rats and mice start hunting for shelter — and your attic looks ideal. A room-by-room checklist to keep them out before they nest.

Why fall is the danger window

Roof rats are the dominant rodent across much of California, and they are climbers — they favor attics, garage rafters, and the upper voids of walls rather than basements. As the dry season ends and the first storms roll in, outdoor food and water get scarce and rodents press toward the warm, dry shelter of your home. The good news: a roof rat needs an opening about the size of a quarter, which means a careful inspection of your roofline can close most of their routes in a weekend.

The exclusion audit

Walk the exterior and the attic with a flashlight and look for the gaps rodents exploit:

• Gaps where the roof meets the fascia, and at roof-line transitions
• Unscreened attic, gable, and foundation vents
• Gaps around plumbing, gas, and cable penetrations
• Tree limbs and overhead wires that touch the roof — roof rats use them as bridges
• Gaps under garage doors and worn weatherstripping
• Crawl space access doors that no longer seal

Seal hard gaps with metal flashing, hardware cloth, or copper mesh packed into the opening — rodents chew straight through foam and steel wool alone.

Cut the food and harborage

Pick fruit promptly off citrus and avocado trees and clear windfall from the ground, since dropped fruit is a reliable rodent buffet in California yards. Store pet food and birdseed in sealed metal or hard-plastic bins, keep firewood and clutter off the ground and away from walls, and trim dense ground cover and ivy that gives rodents cover right up to the foundation.

Trapping done right

Snap traps remain the most reliable do-it-yourself tool. Place them perpendicular to walls where you see droppings or rub marks, and resist the urge to scatter poison bait outdoors — it puts pets and the owls and hawks that hunt rodents at real risk. If you are trapping week after week without progress, the colony is breeding faster than you are removing it.

When to bring in a pro

If you hear scratching in the walls or ceiling at night, find droppings in more than one room, or cannot locate the entry points, source control on your own only goes so far. A professional handles the full sequence — finding and sealing every opening, removing the active population, and cleaning contaminated insulation — in the right order, so the rodents do not simply return to a familiar nest. Ask any pro you hire whether they use exclusion-first methods rather than relying on outdoor bait stations.

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