Rats in the Attic and Walls: A Vallejo Homeowner’s Guide

Why rats end up in Vallejo attics

Roof rats are climbers. They live high, travel along fences, power lines, tree branches and ivy, and look for a warm, dry, quiet spot. An attic is perfect. It has insulation for nesting, no people, and easy routes down into the walls toward your kitchen.

Vallejo gives them a lot to work with:

• Mature trees and ivy. Palms, pines, fruit trees and ivy-covered fences give rats a highway to the roof. Many older streets near downtown and the Heritage District have all of these.
• The waterfront. Rat activity along the waterfront and around the ferry terminal is well known. In 2025 the city added traps and extra street sweeping after a rodent surge downtown, as NBC Bay Area reported.
• Older homes. Houses built before the 1960s often have open eaves, gaps around old vents and settled rooflines. A rat only needs a hole about the size of a quarter.
• Fruit and food outside. Backyard citrus, fallen fruit, birdseed and pet food left on the patio keep rats close to your house.
• Mild winters. It rarely gets cold enough here to slow rats down. When nights get wet and cool from November onward, they move inside.

Norway rats, the heavier ground-living rat, can also get into walls from crawl spaces under raised foundations. They are less likely to be in the attic. Not sure which one you have? Our guide to roof rats vs Norway rats in Vallejo covers the differences.

How rats get into the attic

Here are the entry points we find most on Vallejo homes:

1. Roof and eave gaps. Where the roof meets the fascia board, especially at corners and where two rooflines join.
2. Roof vents and gable vents. Torn or rusted screens are easy to push through.
3. Plumbing and AC line openings. Gaps where pipes, cables or AC lines go through the siding.
4. Garage door corners and weep screeds. A common way in for rats that then climb up inside the walls.
5. Chimneys and old flues. Especially on older homes with unused fireplaces.
6. Crawl space vents. Broken vent screens let rats into the crawl space and from there into walls.
7. Branches touching the roof. Not a hole, but the bridge that leads to one.

Signs you have rats in the attic or walls

Noise is usually the first clue, but it is not the only one. Look for:

• Scratching, scurrying or gnawing sounds at night, often right after dark and again before dawn.
• Droppings in the attic, garage or under sinks. Roof rat droppings are about half an inch long with pointed ends. See our droppings guide for photos and sizes.
• Flattened or tunneled insulation and paths through it.
• Gnaw marks on wood, wiring, storage boxes or pipes.
• Greasy rub marks along beams, rafters and around entry holes, left by rats’ fur.
• A musky, stale smell in the attic or a closet.
• Rats on the fence line or in trees at dusk. If you see one outside, there are usually more nearby.
• Pets staring or pawing at a wall or ceiling.

Is it rats, mice or something else?

Mice make lighter, quicker sounds and leave droppings the size of a grain of rice. Squirrels are active in the daytime, not at night. Raccoons are much louder and heavier. Night-time scratching plus half-inch droppings in the attic in Vallejo usually means roof rats.

Why you should not wait

A few rats turn into a colony fast. Roof rats can breed several times a year, and Vallejo’s mild climate means there is no real off-season. The longer they stay, the bigger the job.

• Wiring damage. Rats gnaw constantly. Chewed wires in attics and walls are a real fire risk.
• Insulation damage. Nesting and urine ruin insulation, which then has to be removed and replaced.
• Health risks. Rat droppings and urine can carry disease. Dust from a contaminated attic should not be swept up dry.
• Smell. A rat that dies inside a wall can leave an odor for weeks.
• More rats. The trails and scent they leave attract new rats, even after the first ones are gone.

What to do about rats in the attic

Step 1: Confirm and find the way in

Before anything else, find out how they are getting in. Walk around the house at dusk and look up. Check the roofline, vents and any spot where branches touch the house. Look in the garage and crawl space for droppings and gnaw marks.

Step 2: Remove the rats

Snap traps placed along the paths rats use in the attic are the most reliable tool. We do not recommend poison for rats inside a home. A poisoned rat often dies inside the wall or ceiling where you cannot reach it. For a step-by-step look at traps and what works, read how to get rid of rats.

Step 3: Seal every entry point

This is the step that actually ends the problem. Gaps get closed with materials rats cannot chew through, such as hardware cloth, sheet metal and metal mesh. Expanding foam alone does not stop rats. Sealing is done once the rats inside are gone, or a rat gets trapped in the wall.

Step 4: Clean up and repair

Droppings, nests and soiled insulation need careful cleanup. Wet the area down with a disinfectant first, wear gloves and a mask, and never sweep or vacuum droppings dry. Heavy contamination usually means insulation removal and replacement.

Step 5: Follow up

Check traps and entry points again over the next couple of weeks. New noise means there is a gap that was missed.

When to call a pro

Some jobs are fine to tackle yourself, like a single mouse in the garage. Rats in the attic are usually not one of them. Call us at (707) 000-0000 if:

• You hear noises in more than one area of the house.
• You cannot find how they are getting in.
• The roofline is too high or steep to inspect safely.
• You have found droppings in the kitchen or near food.
• Traps are catching rats but the noise does not stop.
• The insulation is soiled and needs cleanup.

Our rodent control in Vallejo page explains how we inspect, trap, seal and follow up. If you want to know what goes into the price, see the rat and mouse removal cost guide.