Rats and Mice in San Francisco Garages and Basements

The ground floor is Norway rat territory. UC IPM says that indoors, Norway rats mostly stay in basements and ground-floor areas. In San Francisco that's the garage, the storage room behind it, the laundry area and the space under the front stairs.

Garages here get a lot of traffic and not much attention. The door goes up and down all day, boxes pile up along the walls and the bins sit right inside. It's a good setup for a rat.

The Garage Door

UC IPM says young rats can squeeze under a door with a half-inch gap. On a sloped driveway, garage doors often don't sit flat, and the bottom seal leaves a gap at one corner. Look from inside with the lights off on a sunny day. If light shows, that's a way in. A new bottom seal and side weather stripping are cheap fixes compared to a rat problem.

• Light showing under or beside the garage door
• Chewed corners on the bottom seal
• Droppings along the garage walls and behind boxes
• Gnawed bags of pet food, birdseed or garden supplies

Storage and Bins

The health department tells building owners to stack stored items neatly and at least six inches off the ground, and to keep garbage containers rodent-proof and watertight with tight lids. Move pet food and birdseed into metal or heavy plastic bins. Get boxes onto shelves. If your recycling and compost bins live in the garage, keep the lids shut.

Basements and Crawl Spaces

Older houses have foundation vents and old pipe holes into the basement or crawl space. Screens rust out and holes get left behind when plumbing is redone. A tech will check those, plus the gap where the sewer line and gas line come through the wall. Rodent exclusion covers the sealing and rat control the trapping.

Related: Rat Control, Rodent Exclusion, Attic and Crawl Space Cleanup

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