If you are lying awake listening to a persistent scratching, scurrying, or chewing noise coming from your walls or floorboards at night, you aren’t imagining things. In Northern California—from the coastal hills of Marin County to the valleys of Sonoma and Napa—these sounds are the classic, unmistakable warning signs of a structural rodent infestation.
When those noises seem concentrated near the baseboards or beneath your floor, the source is almost always down in your crawl space. Understanding why this happens, what animals are responsible, and why standard pest control methods fail is the first step toward reclaiming your peace of mind and protecting your property.
Why Do You Only Hear the Scratching at Night?
The sudden racket that starts right after you turn off the lights isn’t a coincidence. Both rats (specifically roof rats and Norway rats) and mice are primarily nocturnal creatures. They spend the daylight hours nesting safely in dark, undisturbed areas. As night falls, they wake up and begin foraging for food and water, moving actively through the hidden pathways inside your home.
Your crawl space provides the perfect staging ground. It is dark, protected from predators, and filled with fiberglass insulation that makes premium nesting material. When rodents travel out of the crawl space to search for food, they don’t walk across your living room floor; they climb up inside the hollow cavities of your walls. The scraping sounds you hear are their claws pulling against the drywall and structural framing as they move between the crawl space and your attic.
The Crawl Space: The Vulnerable Underbelly of Bay Area Homes
Many homes in towns like Novato, San Rafael, and Santa Rosa are built on raised foundations with crawl spaces. While this architecture is excellent for managing sloping terrain and accessing plumbing, it presents a massive vulnerability if it isn’t properly proofed.
Rodents can squeeze through shockingly small openings. A mouse needs a gap no larger than a dime, while a fully grown rat can fit through a hole the size of a quarter. Common entry points in your crawl space include:
- Damaged foundation vents: Torn, rusted, or standard plastic vent screens are easily chewed through or pushed aside by determined pests.
- Unsealed utility penetrations: Gaps around plumbing pipes, electrical conduits, and HVAC lines that lead from the outside directly into the crawl space subfloor.
- Rotting rim joists and sill plates: Over time, moisture can soften the wood along your foundation line, allowing rats to chew their way inside.
- Missing crawl space access covers: Ground-level access doors that are loose-fitting or made of rotting wood provide an open invitation.
Why Traditional Pest Control Won’t Stop the Noise
When homeowners hear chewing in the walls, their first instinct is often to call a traditional exterminator who sets out toxic bait boxes. In the Bay Area, this approach is both ineffective and hazardous.
First, poison does not stop the scratching noises; it pauses them temporarily. If an exterminator kills the rats currently living under your house, the open holes remain. New rodents tracking the pheromones of the old ones will move into the vacant crawl space within weeks, restarting the cycle.
Second, a poisoned rodent doesn’t step outside to die. It crawls deep inside your wall voids or insulation and dies there. This leads to weeks of unbearable rotting odors, fly infestations, and expensive structural damage to locate the carcass. Furthermore, poisoned rodents that wander outside pose a lethal threat to local Northern California wildlife, including owls, hawks, bobcats, and neighborhood pets.
The Done Right Solution: Permanent, Poison-Free Structural Sealing
At Done Right Rodent Proofing, we don’t use band-aid solutions. We fix the root cause of the noise by performing a complete structural exclusion.
- Thorough Inspection: We crawl into the spaces most people avoid to map out every single entry point along your foundation and subfloor.
- Construction-Grade Exclusion: We permanently seal every gap using heavy-duty, commercial-grade materials that rodents cannot chew through—including 1/4-inch steel hardware cloth, solid metal flashing, concrete, and lumber. We never rely on temporary quick-fixes like spray foam or steel wool.
- Clean Trapping: Once the house is sealed tight so nothing else can get in, we place mechanical snap-traps inside the crawl space to eliminate the pests trapped inside. We check and manage these traps every 3 to 5 days so you never have to deal with them.
- Industry-Leading 3-Year Guarantee: We are so confident in our construction-grade sealing that we back our work with a full 3-year rodent-free guarantee. If new rodents manage to break through, we return and fix it at absolutely no additional cost to you.
Stop letting rodents ruin your sleep and damage your home’s infrastructure. Contact Done Right Rodent Proofing today for a comprehensive, poison-free crawl space inspection.