Granite Bay · Placer County
Norway Rat Control in Granite Bay, CA
Norway rats burrow under foundations and invade crawlspaces. Professional removal and permanent exclusion.
Know Your Pest
What Is a Norway Rat?
Rattus norvegicus — also called the brown rat, sewer rat, or wharf rat — is the larger of California’s two common rat species. Adults reach 16–20 inches nose to tail and weigh 12–16 oz. Their small ears, blunt nose, and tail shorter than their body length immediately distinguish them from the slender roof rat.
Norway rats are ground-level burrowers. In Granite Bay, they exploit irrigation lines, compost bins, and overgrown vegetation near foundations. They access homes through floor drains, utility pipe gaps, cracked foundation vents, and any opening ≥½ inch at or below grade.
Once established under a slab or in a crawlspace, Norway rats gnaw through PVC plumbing, vapor barriers, and floor insulation. A colony of 20 adults produces over 25,000 droppings per year and contaminates soil with leptospirosis bacteria.
Early Warning Signs
Signs of Norway Rats Around Your Home
2–3 inch diameter holes near the foundation, under decking, along fence lines, or beside compost bins. Fresh burrows have smooth, compacted entry ramps.
Capsule-shaped pellets ¾ inch long with blunt ends — larger than roof rat droppings. Found along walls, in garage corners, under sinks, and near food storage.
Heavy thumping and scratching in lower wall cavities and beneath the floor. Norway rats are more active at dusk and the first few hours after dark.
Norway rats chew continuously to file their incisors. PVC pipes, irrigation tubes, and electrical conduit under houses are common targets.
Dark grease marks at rat height along the base of walls, especially in garages, utility rooms, and under kitchen cabinets near appliances.
Dogs and cats fixating on a specific wall, cabinet, or section of floor. Animals detect rat activity — urine scent in particular — well before humans do.
Our Approach
How We Eliminate Norway Rats
We inspect the perimeter, crawlspace, utility penetrations, and drainage pathways. Burrow mapping and runway identification guide the treatment plan. Moisture sources and harborage areas are documented.
Heavy-duty snap traps and enclosed bait stations are placed at burrow entrances, along confirmed runways, and in crawlspace entry areas. We use tamper-resistant stations where children or pets may access the area.
Concrete, galvanized hardware cloth, and sheet metal are used to seal foundation vents, utility entries, and burrow access points. Norway rats cannot chew through hardened metal or poured concrete.
Written recommendations for compost bin management, irrigation repair, wood pile placement, and vegetation clearance — the environmental conditions that attracted Norway rats in the first place.
Found Burrow Holes Near Your Foundation?
Norway rat colonies expand fast and spread disease. Get a professional inspection this week.
(279) 227-5858Fully Insured · Placer County
Frequently Asked Questions
Yes, though it’s uncommon. Norway rats are strong swimmers and can navigate sewer lines. This is most likely in homes with older clay sewer pipes or broken lateral connections. A licensed plumber can inspect and reline vulnerable sections.
A female can produce 5–7 litters per year with 8–12 pups per litter. Pups are sexually mature in 5 weeks. A single mating pair can theoretically grow to 2,000+ rats in a year without intervention.
Yes. Leptospirosis (spread through urine in water or soil), rat-bite fever, salmonellosis, and hantavirus are all documented risks. Children playing near soil adjacent to burrows are at highest risk. Cleanup of burrow sites requires protective equipment.
Norway Rat Control in Granite Bay
Rodent inspection and exclusion in Granite Bay. Professional-grade materials. Serving Granite Bay and all of Placer County.
Exclusion Approach
How Norway Rat Exclusion Differs From Roof Rat Exclusion
Norway rats and roof rats share the same suburban neighborhoods in Granite Bay and Placer County but exploit entirely different entry routes. Getting the exclusion right requires understanding which species you are dealing with before picking up a tool.
Norway rats are ground-level animals. They burrow, and they enter structures through the lowest points: gaps in the foundation stem wall, improperly sealed crawl space vents, floor drain pipes, gaps where utility conduits enter below grade, and through concrete cracks at grade level. They are strong enough to enlarge existing openings by gnawing, and they follow established burrow runs that return to the same entry points generation after generation.
Roof rats, by contrast, rarely come near the foundation. They travel above ground through tree canopies and gain entry at the roofline through tile gaps, gable vents, and eave transitions. A home with both species active — which occurs in Granite Bay properties near Miners Ravine or the Folsom Lake creek drainages — requires entry point mapping at both levels before any sealing begins.
Norway Rat Entry Points: What We Check
Foundation vents lacking intact hardware cloth are the single most common Norway rat entry route in Granite Bay homes. Standard vent screens use 1/4-inch mesh; we use 1/4-inch galvanized hardware cloth at minimum, 1/8-inch where Norway rat gnawing is evident.
Where plumbing, electrical conduit, or HVAC lines enter below the sill plate level, any gap larger than 1/4 inch is a Norway rat route. We probe every penetration with a steel pick before sealing with hydraulic cement or galvanized sheet metal collars.
Placer County’s clay-heavy soils expand and contract seasonally. Concrete foundation stems develop step cracks at corners that widen gradually. Norway rats exploit any crack reaching 1/2 inch width. We use hydraulic cement, not caulk, for these repairs.
The gap between the garage slab and the wall plate frame is frequently unsealed in homes built before 1990. Norway rats enter here and use the interior garage wall cavity as a travel route throughout the structure.
Norway Rats in Placer County: Local Habitat Drivers
According to UC IPM, Norway rat populations are closely associated with water sources. In Placer County, this means heightened Norway rat pressure in areas near:
- Miners Ravine and its tributaries in Rocklin
- Dry Creek, Secret Ravine, and Linda Creek in Roseville
- The American River corridor through Folsom and southern Placer County
- Agricultural irrigation ditches in Lincoln, Loomis, and Newcastle areas
- Properties with improperly drained irrigation systems or persistent standing water
Source: UC IPM Pest Note 74106: Rats (Rattus spp.) — University of California Agriculture and Natural Resources.