Bats hide in the structural gaps between a home’s exterior and interior walls, most often in attics, wall voids, soffits, and chimney spaces. They can squeeze through openings as small as half an inch, which means almost any crack, gap, or loose piece of siding is a potential entryway. Most bat species prefer roosting spots above 10 feet, but some will settle into basements, cellars, and crawl spaces beneath the house.
The Most Common Hiding Spots
Bats don’t nest in the open rooms of your house. They tuck themselves into tight, enclosed spaces within the building’s structure. Think of the voids between your drywall and your exterior siding, the space above your ceiling but below the roofline, or the gaps where different building materials meet. These areas are dark, sheltered from wind, and difficult for predators to reach.
The specific spots bats favor most include:
- Attics and roof spaces: The single most common roosting location, especially in summer. Attics trap heat, which bats actively seek out.
- Wall cavities: Bats enter through exterior gaps and roost inside the walls themselves, sometimes descending from the attic into lower floors.
- Soffits and eaves: The underside of roof overhangs often has vents or small gaps where bats slip in.
- Chimneys: A missing or broken chimney cap is one of the easiest entry points. Bats roost on the interior walls of the chimney shaft.
- Behind shutters and downspouts: Some bats roost on exterior walls behind objects that provide a narrow, sheltered gap.
- Dormer junctions: Where a dormer meets the main roofline, there’s almost always a small seam or gap in the construction.
- Gable vents: A torn or deteriorated screen on a gable vent is an open invitation.
- Under window sills and loose shingles: Less obvious, but bats will exploit any gap that gives them access to a protected void.
Older, taller buildings are significantly more likely to have bat colonies. Research from Penn State found that bat-occupied buildings were older and had more access points than unoccupied ones. Buildings with metal (tin) roofs were also more likely to harbor bats, likely because metal roofing creates warm air pockets underneath.
Why Bats Choose Certain Spots
Temperature is the biggest factor. In paired comparisons of similar attics, the ones bats chose were significantly warmer and had wider temperature gradients than empty ones. This matters because bats, especially females raising pups, need warm environments to support their young’s rapid growth. A south-facing attic that bakes in the afternoon sun is far more attractive than a cool, well-ventilated one.
Interestingly, light levels, humidity, and how often humans disturbed the space did not differ between occupied and unoccupied attics. Bats aren’t as bothered by occasional human presence as you might expect. What they care about is heat and access.
Where Bats Hide Changes With the Season
In summer, female bats gather in maternity colonies to give birth and raise pups. These colonies gravitate toward the hottest spots in a building, typically attics and upper wall voids. A maternity colony can range from a handful of bats to several hundred, and they return to the same roost year after year. This is peak season for noticing bats in your home, roughly May through August.
In winter, bats need the opposite conditions. Hibernating bats seek out cold but above-freezing spaces called hibernacula. In a house, this could mean basements, cellars, interior wall cavities on the north side of the building, or unheated sections of the structure. Some homeowners discover a bat in their living space during winter because a hibernating bat woke up and wandered from its hiding spot deeper in the walls.
How to Find Where They’re Hiding
You won’t always see the bats themselves, but they leave clear evidence. The most reliable sign is droppings (guano) accumulating below a roost or entry point. Bat droppings look similar to mouse droppings at first glance, but they crumble easily when pressed and contain shiny flecks of undigested insect parts. Mouse droppings are harder and lack the sparkle. Bat droppings also never contain the white, chalky material you’d see from reptiles or birds.
The second major clue is rub marks. Where bats repeatedly squeeze through an opening, body oils from their fur mix with dust and create a smooth, slightly sticky stain that ranges from yellowish-brown to nearly black. These marks often appear along walls, between bricks, under loose woodwork, and around gaps in siding. If you look closely, you may spot a few tiny hairs stuck in the residue.
Sound is another giveaway. Bats scratch, crawl, and vocalize inside attics, behind walls, and between floors. They get noticeably louder on hot days (when attic temperatures rise and they become restless), just before dusk when they’re preparing to leave, and at dawn when they return. If you hear faint squeaking or scratching from above your ceiling around sunset, that’s a strong indicator.
To pinpoint entry points from outside, watch your roofline at dusk during warm months. Bats exit within about 30 minutes of sunset, and you can often see them streaming out of a specific gap or vent.
Health Risks Near Roosting Sites
Accumulated bat guano can harbor a fungus that causes histoplasmosis, a lung infection you contract by breathing in airborne spores. The spores become airborne when droppings are disturbed, swept, or shoveled. This is why cleaning up a large guano deposit yourself is risky, particularly in an enclosed space like an attic. Professional hazardous waste removal is the safer route for significant accumulations.
Rabies is the other concern. Only a small percentage of bats carry rabies, but any direct contact with a bat (or finding a bat in a room where someone was sleeping) should be treated seriously. Bats have tiny teeth, and a bite can go unnoticed.
Getting Bats Out Safely
Sealing bats inside a house doesn’t work and can make things worse, pushing them deeper into living spaces as they search for a way out. The standard approach is exclusion: installing one-way devices over entry points so bats can leave at dusk but can’t return. Once all bats have departed, the entry points are permanently sealed.
Timing matters. Exclusion is restricted during maternity season (roughly mid-May through the end of July in many states) because flightless pups inside the roost would be trapped and die. Winter exclusion is also restricted in some areas because hibernating bats won’t leave on their own. In Ohio, for example, exclusion is prohibited from May 16 through July 31 when five or more bats are present, and again from October 15 through March 31 if any bats are found. Other states have similar rules, so check your local wildlife agency before taking action.
The best window for exclusion is typically August through early October, after pups can fly but before bats settle into winter hibernation. Every gap, crack, and hole larger than half an inch needs to be sealed, which often means a thorough inspection of the entire roofline, soffits, siding joints, chimney, and foundation. Missing even one opening means the colony will find its way back in.