Rats and Mice in San Francisco: Who Handles What

Which rats and mice live in San Francisco?

Three species matter in the city: Norway rats, roof rats and house mice. The San Francisco Department of Public Health names them as the important urban rodents. UC IPM adds that roof and Norway rats live in almost all California cities, and the Presidio's species list includes the roof rat.

Knowing which animal you have is the first step, because the species decides where it nests and how it gets in. The health department's approach reflects this. Its program identifies the species first, and only then surveys for the attractant that brought the animals. That order makes sense. A fix aimed at a burrowing rat will not work on a climbing one.

The Norway rat is the heavier, ground-oriented animal. UC IPM says it burrows along foundations and under rubbish or woodpiles. Look for burrow openings at the base of walls, under sheds and beneath dense ground cover. The roof rat is the climber. UC IPM says it nests above ground in shrubs, trees and dense vegetation, and indoors in attics, walls, false ceilings and cabinets. In a city of steep lots, hedges and old houses with attics, both have plenty of choice.

House mice are smaller and live closer to people, inside cabinets, behind appliances and in wall voids. They can squeeze through small gaps, which is why UC IPM puts the mouse sealing threshold at about 1/4 inch. The National Park Service species list for the Presidio includes the roof rat, a reminder that rats are part of the picture even beside the city's most protected green space. Our rat control, roof rat control and mouse control pages cover each animal.

What does the city's program cover?

The San Francisco Department of Public Health runs a proactive and complaint-based rodent program. It identifies the species, then surveys for the attractant. The city mainly handles public property and can inspect private buildings and food facilities when vermin are reported. Private owners deal with infestations on their own land.

The public side of rodent control in the city is the health department's vector control work. Based on its public description, the program has two parts: it looks for problems on its own, and it responds to complaints. When a complaint comes in, the approach is to identify the species and then survey the surroundings for the attractant, which is often garbage, food waste or harborage such as clutter and overgrown plants.

The key limit for property owners is where the city's responsibility ends. The city mainly handles public property, such as sidewalks, public spaces and city-owned sites. It can inspect private buildings and food facilities when vermin are reported, but dealing with an infestation on private land is the owner's job. That is a normal split in many cities, and it is why a homeowner with rats in the attic cannot count on the city to fix it.

The department's pages say rodent complaints go through 311, which records them and routes them to Environmental Health, and they recommend pest services licensed by the San Francisco County Agricultural Commissioner that use integrated pest management principles. The same guidance says a residential owner or manager must investigate a report of pest activity within 72 hours. Those pages also say the department has moved its rodent help to a newer sf.gov page, so read this as the department's guidance and check sf.gov for the current way to report. The current phone number, the exact 311 steps and any fine amounts are not covered here because we could not source them. A company like San Francisco Pest Control handles the private-property side: inspection, sealing and control.

What attracts rats and mice to a building?

Garbage is a major attractant, according to the health department's description of its work. Food waste, pet food, bird seed, clutter and dense vegetation add to it, and open gaps let animals in. Remove the attractants and close the entry points, and the building becomes much less welcoming.

Rodents need food, water and shelter, and a city building often supplies all three by accident. Garbage is the headline item. Open bags, overfull carts and lids that will not close all feed rats. Compost bins and pet food left outside do the same. In a dense neighborhood where bins sit close together, a single poorly managed cart can serve a whole block.

Shelter is the second half. Dense shrubs, ivy on walls, stacked boards and clutter in garages and yards give rats a place to nest. For roof rats, a branch that touches the roof acts as a bridge. For Norway rats, a woodpile against a fence is a ready-made burrow site. Cleaning up the yard is not glamorous, but it often changes the situation faster than any trap.

Entry is the third piece. A rodent will use whatever gap it finds: around pipes, vents and utility lines, at the edges of garage doors, through damaged screens and where building materials meet. The next section explains how to close them. If you are unsure where animals are getting in, a technician can trace the route. The rodent exclusion page covers the sealing work.

How do I seal a building against rats and mice?

Seal gaps larger than 1/2 inch against rats, and about 1/4 inch against mice, with steel wool, wire screen or sheet metal, as UC IPM advises, and keep garbage in tight-lidded containers. Start with gaps around pipes, vents and utility lines, then check doors, screens and the roofline. Sealing only addresses the structure. Nothing here involves trapping or relocating wildlife.

Sealing is the most lasting step in rodent control, because it fixes the building instead of just removing the animals inside. The rule UC IPM gives for rats is simple: close any gap larger than 1/2 inch, and for mice about 1/4 inch. Use steel wool, wire screen or sheet metal, since gnawing animals can chew through softer materials. Foam or caulk alone is usually not enough for a determined rodent, though it can hold a metal backing in place.

Walk the outside and the inside. Outside, look at the foundation vents, the points where pipes and wires enter the wall, the gaps under doors and the junction between roof and wall. Inside, look under sinks, behind appliances and in the attic and crawl space. Roof rats use the upper parts of a building, so check the eaves, the soffits and roof vents as well as the ground level.

This site does not trap, remove or relocate wildlife, and sealing the structure is the work described here. Larger animals such as raccoons and skunks fall under different rules. Our attic and crawl space rodent cleanup page covers cleaning up after rodents, and wildlife-proofing explains sealing structure against larger animals.

• Seal gaps over 1/2 inch against rats and about 1/4 inch against mice with steel wool, wire screen or sheet metal.
• Check pipe and wire penetrations, foundation vents, door sweeps and roof vents.
• Keep garbage in tight-lidded containers and do not leave bags out.
• Cut back branches and vines that touch the roof or walls.
• Move woodpiles, lumber and rubbish away from foundations and fences.

What do the agencies around San Francisco do for rodents?

It varies by county. San Mateo County's vector control district gives free rodent inspections with a repair report, typically the next business day, and re-inspects after repairs, but its staff do not trap or seal. Marin-Sonoma's district offers rodent exclusion consultations. Alameda County does rat site inspections except in Berkeley.

If you live just outside the city, the public service you can reach changes. The table below sets out what could be sourced. Where it says not sourced, we could not confirm which agency serves the place, so no claim is made and no agency phone numbers are given. Check the agency's own website for current details.

The common thread is that public agencies inspect and advise, and the treatment of private property is mostly left to the owner. That is true even where a district offers a free inspection. The report can be useful to hand to a technician, since it records what the inspector found.

What should I do first if I find rats or mice?

Identify what you are seeing, remove the attractants, and find where the animals are getting in. Look for droppings, gnawing, burrows and noises, and note whether they are at ground level or overhead. Then call a technician to inspect, seal and control. The city does not usually handle private-property infestations.

Start by looking. Droppings, gnaw marks, greasy rub marks along walls and sounds in the attic or walls are the usual signs. Overhead noises at night often point to roof rats. Burrows at the base of a wall or beneath a shed often point to Norway rats. Small droppings in kitchen cabinets and behind appliances often point to mice. These are rough guides, not a diagnosis, and a technician can confirm.

Next, take away the draw. Close up the garbage, bring pet food inside, clear clutter and trim the plants that touch your building. Do not rely on poison alone. It does not fix how they got in, and an animal that dies inside a wall creates a separate problem. A technician will combine control with sealing so that the problem does not simply return.

When you are ready, call (855) 974-4733. Phones are answered 24/7, and a same-day visit is offered only when a technician is free. The price is confirmed on site before anything is applied. If you are in a shared building, tell the technician, because a problem in one unit often connects to the next.

Why do old San Francisco buildings make rodent control harder?

Older buildings have more gaps, more hidden voids and more shared walls, so animals have more ways in and more places to hide. Roughly 45 percent of San Francisco homes were built in 1939 or earlier. That does not make rodent control impossible, but it makes a thorough inspection more important.

The city's housing is old, and a lot of it is attached. Roughly 45 percent of homes were built in 1939 or earlier, according to figures reported by home-data sites, and the median home dates from about 1948. Those figures come from survey estimates, so treat them as a general picture. For rodents, the building's age matters because decades of settling, repairs and utility changes create gaps, and older raised floors and attics offer shelter.

For older houses, a lasting result usually comes from combining a thorough inspection, careful sealing at every level and attention to garbage and vegetation. A technician will look at the whole building, from the roofline down to the foundation. The general pest control page describes the routine visit, and the attic and crawl space rodent cleanup page covers what happens after the animals are gone.