Inside your unit, while you wait.

Where to look, and what to use.

1. A. Under the sinks. Empty the cabinet under each sink, kitchen and bathroom. Shine a flashlight where the pipes come through the wall and the cabinet floor. A gap about the width of your finger around a pipe is enough for a mouse. Block it: Cut 1/4-inch hardware cloth to fit snug around each pipe and press it into the gap, then seal over it with interior caulk. A small gap can take caulk alone. Keep the shut-off valves easy to reach.
2. B. Behind the stove, fridge and dishwasher. Slide the fridge out and look at the wall behind it for holes around the water line and the outlet. Look behind the stove and under the dishwasher’s front panel with a flashlight, for holes around the gas line and pipes. Block it: Seal small holes around water lines with interior caulk, with hardware cloth packed in behind any larger hole. Don’t move a gas stove or touch the gas line yourself. Ask your landlord to seal around it.
3. C. Baseboard gaps and corners. Run a flashlight along the baseboards, especially in the corners and behind furniture. Look for gaps where the baseboard has pulled away from the wall or floor, and for droppings or dark rub marks along the wall. Block it: Seal gaps along the baseboard with interior caulk. Pack hardware cloth into any larger hole first, then caulk over it. A removable caulk lets you leave the wall as you found it.
4. D. Radiator, heating and AC lines. Look where radiator or heating pipes come up through the floor or wall, and where AC lines come through the wall to an indoor unit. There’s often an open ring of gap around the pipe. Block it: Fit a split metal pipe collar around each radiator or heating pipe. It closes the ring without fixing anything to the pipe, and metal is safe on a hot pipe. Around AC lines, press hardware cloth into the gap and seal it with interior caulk.
5. E. Under the entry door. With the hallway lights on and yours off, look at the bottom of your entry door. If you can see light under it, a mouse can see the way in. Block it: A custom metal door sweep closes it, bent to fit from aluminum flashing. Ask your landlord in writing to fit one, or fit it yourself with their written OK.
6. F. Closets and the water heater. Check the back corners of each closet, and the floor and wall behind the water heater or in the utility closet, where pipes and lines come through. Look for gaps, droppings, and shredded paper or fabric used for nesting. Block it: Press hardware cloth into gaps at the closet corners and seal over it with interior caulk. Around a gas water heater, don’t block the air it needs or its vent, and don’t move it. Seal only the gaps around the pipes in the wall, or leave it to your landlord.
7. G. Around the tub access panel. Find the panel behind the tub’s plumbing, often in a closet or hallway on the other side of the tub wall. Open it and look with a flashlight for gaps around the pipes, and for droppings inside. Block it: The panel is meant to open, so don’t seal it shut. Inside, press hardware cloth around the pipes and seal it with interior caulk. Close any gap around the panel’s edge with a removable caulk, so it still opens.
8. H. Holes in the backs of cabinets. Empty the lower cabinets and look at the back panels and corners for holes, often where pipes or wires once ran. Look for droppings and chew marks. Block it: Cover each hole with a piece of metal flashing or a metal plate, or hardware cloth for a small one. Hold it with removable mounting tape, or small screws if your landlord says OK in writing. Seal the edges with interior caulk.

What to use: 1/4-inch hardware cloth, interior caulk or sealant (with hardware cloth behind larger holes), metal plates or flashing, and a custom metal door sweep. Pick removable options so nothing damages the unit.

Tell your landlord in writing. Photograph each spot and send the photos to your landlord in writing. Ask them to seal the whole building from the outside at once. Mice already inside? Use enclosed snap traps, used with sealing.

Write the note to your landlord →