Raccoon outdoors on a downspout (C) Daniel FriedmanKeep Bats, Birds, Mice, Rats, Squirrels, Raccoons Out of Your Building

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Animal entry points in buildings:

This article series discusses how to find where animals are getting into your building and how to keep them out, including bats, birds, rats, mice, and squirrels and even raccoons.

This article series focuses on removing pet or other animal odors from buildings due to pet urine, pet feces, wild animal urine, or even human urine on and around buildings or on clothing and other soft materials.

Below; the little stuffed animals in this photo include a skunk - both were innocent of any pet-crimes, but they had been placed at either side of a basement door jamb to cover stains from basement water entry.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Suggestions for Finding the Source of Animal Entry Points in buildings

Stuffed animals were hiding building damage (C) Daniel FriedmanArticle Contents

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Watch out: in addition to their common role as allergens, animal feces, urine, even hair can offer serious health hazards including from various pathogens: bacteria, viruses, even possibly rabies.

Watch out: also for wild animal bites, bacterial and viral hazards when entering confined spaces where invaders are or have been present.

The author (DF) became temporarily ill after (foolishly) working in a "clean looking" crawl space that later he realized had a heavy contamination of fecal and urine contaminated mouse dust. Bat and rodent droppings as well as bird droppings can be a source of a pathogen potentially dangerous to humans, the fungus Histoplasma capsulatum.

Watch out: before sealing up a hole in a soffit or wall where squirrels or bats are entering your building, make sure the animals are not going to be trapped inside where they will be mad, frightened, hostile, even dangerous (like a rabid raccoon), or ultimately dead and another source of stink.

What to do if a Bat Gets in Your Home.

Brown bat captured by Daniel Friedman(C) Daniel FriedmanWhat Percentage of Bats Carry Rabies?

The brown bat shown at left was captured in a Poughkeepsie, New York home when an agile family cat nabbed the bat mid-swoop.

Watch out: do not handle (touch directly) sick or dead bats or other rodents.

The owners worried that the cat was going to need rabies shots. According to the U.S. CDC, only about six percent of bats captured and tested had rabies. If you consider that it's the weaker old bats or sicker bats of any age who are more likely to be captured, that suggests that in the total brown bat population the percentage suffering from rabies is probably considerably less than six percent.

After posing this bat for a few photos, we delivered the brown bat shown at left to the county health department whose tests showed that it may have been elderly or ill but it did not have rabies. The U.S. CDC advises:

Whenever possible, the bat should be captured and sent to a laboratory for rabies testing. People can't get rabies just from seeing a bat in an attic, in a cave, at summer camp, or from a distance while it is flying.

In addition, people can't get rabies from having contact with bat guano (feces), blood, or urine, or from touching a bat on its fur. If you think your pet has been bitten by a bat, contact a veterinarian or your health department for assistance immediately and have the bat tested for rabies.

Remember to keep vaccinations current for cats, dogs, and other animals. - U.S. CDC, "Learning about bats and rabies", retrieved 3 June 2015, original source

If you capture a bat or encounter a dead one, do not handle it. If you capture a bat have it tested for rabies if people or pets have been exposed to it.

If no one has been exposed or is likely to be exposed to the animal, testing may not be necessary: check with your local department of health.

Local health departments do not always advise testing animals for rabies. When a rabid skunk tottered around in our neighbourhood and was found dead the next day the New York Dutchess County health department advised not to touch it but that they were not interested in testing it for rabies unless we thought that someone may have come in contact with it.

What to Do if You are Bitten or Scratched by a Bat or if You Think You Were?

If you are bitten by a bat you probably will know it, but as you can see in our bat photograph above the little brown bat's teeth are tiny. A bite mark may disappear quickly as may scratch marks from their little bat toes or bat wingtip claws - shown in our two photographs just below.

Brown bat toe claws (C) Daniel Friedman

Watch out: If you are bitten or scratched by an unfamiliar animal, wild or domestic, wash the wound thoroughly with soap and water and seek medical attention right away.

Here is the US CDC advice for what to do if you are not sure if you have been bitten or scratched by a bat:

Brown bat wingtip claws (C) Daniel Friedman

If you woke up because a bat landed on you while you were sleeping or if you awakened and found a bat in your room, you should try to safely capture the bat and have it tested.

The same precautions should be used if you see a bat in a room with an unattended child, or see a bat near a mentally impaired or intoxicated person.

The small teeth of the bat can make a bite difficult to find. Be safe and in these situations, try to safely capture the bat, have the bat tested, and seek medical advice. - U.S. CDC, "Learning about bats and rabies", retrieved 3 June 2015, original source

Common Spots for Animal Entry in Buildings: Bats, Birds, Rodents, Snakes

Brown bat photograph (C) Daniel Friedman Stains from bats on a building wall (C) Daniel Friedman

Above & below are more bat-invasion photographs. You will see that the cupped metal roofing formed a nice opening for bats to enter this home, and again, a telltale collection of bat guano droppings below this very spot. Birds and squirrels also enter buildings at openings like this, as we discuss just below.

Droppings indicate bat activity at a building (C) Daniel Friedman

Watch out: do not kill bats unnecessarily. Bats are already in trouble in many areas of the world, including some of the 45 species found in the U.S. And we need them. Bats eat large numbers of night-flying insect pests (such as mosquitoes) and are an important part of our environment.

Avoid closing bat roosting openings in buildings between May and August (in the northern hemisphere) because you may trap young bats in the building. Young bats that have not yet become able to fly won't escape and will die in the building.

Droppings indicate bat activity at a building (C) Daniel Friedman

Watch out: Histoplasmosis (from bat droppings) is an infection caused by inhalation of Histoplasma capsulatum. In people with compromised immune system this can be a particularly dangerous infection, potentially fatal if not treated. See also granuloma, iritis, lung nodules. More information is

Entry point for bats at a building (C) Daniel Friedman

Bird entry point into a roof overhang(C) Daniel Friedman

Bird dropping stains on an attic beam  (C) Daniel Friedman

Watch out: Cryptococcus infection (cryptococcosis): (from bird droppings), at primary risk are people with compromised immune system but normal adults can also be infected by inhalation of Cryptococcus neoformans, leading to a form of meningial encephalitis. Cryptococcosis is a fungal disease caused by Cryptococcus neoformans or Cryptococcus gattii.

Most people do not get sick with cryptococcosis, but some people are more likely than others to get this disease. For these people, cryptococcosis can cause serious symptoms of lung, brain and spinal cord disease, such as headaches, fever, cough, shortness of breath, and night sweats. Cryptococcus neoformans is found in bird droppings. More information is

Dead mouse odor (C) Daniel Friedman

Dead bat found in a building attic. We also find dead bats in suspended ceilings, ductwork, and other areas (C) Daniel Friedman

Steel wool used to close rodent entry point below a kitchen sink (C) Daniel Friedman

Advice for Keeping Bats, Rats, Mice, Raccoons or Squirrels out of Your Home

Skunk on the Vassar Golf Course (C) Daniel Friedman

Our photo above shows a skunk rummaging on a golf course. If you see a skunk meandering in daylight stay well away - stay away any time for that matter. This skunk was found dead two days after its photo was taken, probably due to rabies.

Steel wool used to plug rodent entry points (C) Daniel Friedman

Above you see use of steel wool used to plug rodent entry points in a building. Pest control experts recommend several simple steps that will discourage mice and squirrels from moving into your building as they are inclined to do particularly at the beginning of cold weather:

Open petfood invites mice and rats indoors (C) Daniel Friedman

Bats at the gable end of a home attic (C)

Above are bats on the outside of the screened attic gable vent opening of a U.S. home. These bats were not able to enter the home but heaven knows the effect on the bats if the burglar arm speaker (at left in the photo) sounds.

Loudspeakers are not likely to be an effective bat or rodent deterrent.

Snow time means thinking too late about heating costs

Trim shrubs at least a foot away from the building walls; we prefer 18". This also reduces the attractiveness of the building to insect pests such as termites and carpenter ants.

If your home is in an area where Norway rats are a problem, keep low growing shrubs away from your building walls entirely as those rats burrow under them, especially Junipers and Taxus.


If your building odor complaint source is found to be outdoors, see URINE ODOR REMOVAL at BUILDING EXTERIOR.

Also see URINE ODOR REMOVAL in CLOTHING This article describes bacterial/enzyme based cleaners that may be extra effective in removing human or animal urine odors from clothing, diapers, bedding, towels, etc.

Mice Problems Indoors

Dead mouse odor (C) Daniel Friedman

Mouse-specific tips on how to get rid of mice in your home and how to keep them out are at MOUSE in the HOUSE - separate article

Raccoons Like it Indoors in Buildings

Raccoon outdoors on a downspout (C) Daniel Friedman

To give the racooons more space, we move them to RACCOONS in the ATTIC, a separate article that relates a true story about raccoons invading a New York home at CHristmas. A brief excerpt is just below.

Dan and Laura were snuggled up reading in bed on a cold Poughkeepsie January night. Suddenly overhead they heard

SMACK! rattle, rattle, rattle, rattle, rattle, rattle, roll. Something or someone was in the attic! Now they heard the sound of little clawed feet scampering across the attic floor just over their heads.

The home, built in 1900, was a neo-Victorian with a large walk-up attic wherein were stored the usual detritus, old rugs, suitcases, trunks, broken lamps, bicycle parts, and other who-knows-what. Some animal, maybe more than one of them, was smashing something around in the attic. What the hey?

Dan tiptoes over to the door at the bottom of the attic stairs in his pajamas. He leans an ear against the cold red-varnished wood. Cold air leaks out of the attic and rolls across his bare toes adding to the chill of the sounds of intruders above.

Also see POETRY & SHORT FICTION, Daniel Friedman

Are There Squirrels in the Attic?

Bird entry point into a roof overhang(C) Daniel Friedman

Our photos show a stunning nest project built by squirrels in the attic of a 1960's home in New York. The squirrels entered through openings in the home's aluminum soffit covering, tore up fiberglass insulation, and built the mounded nest in our photo at below left. Squirrel droppings on attic insulation are shown in our second photo, below-right.

Bird dropping stains on an attic beam  (C) Daniel Friedman

Below we show another sign of squirrel invasion of an attic: leaves brought into the attic to add to insulation as a nesting material.

Bird entry point into a roof overhang(C) Daniel Friedman

One of our favorite squirrel invasion indicator photos provided by a reader is shown at below right. When squirrels nest or simply hide in an aluminum downspout, the sound or smell of the squirrel can be enough to drive some dogs mad as they try to tear their way into the squirrel's hiding place (below right).

Bird dropping stains on an attic beam  (C) Daniel Friedman

Animal Feces & Urine Detection & Clean-Up

Bat guano (bat poop or bat shit) indoors in the attic of a church (C) Daniel Friedman

Our photo at above left of deep piles of bat guano in the attic of a pre-1900 church was taken during a building inspection in Staatsburgh, New York. When you find mountains of bat droppings like this you can figure that bats have been inhabiting this building for decades.

Reader Question: how do I clean up bat droppings & bat urine in our cabin?

We discovered a huge colony of bats living under the roof of our log cabin.

I used a black-light (see UV LIGHT BLACK LIGHT USES) and found bat urine on all the main beams in the house as well as all the walls in the cabin. I have had restoration people tell me it could be cleaned and others said no all the wood is going to have to be replaced who is telling the truth?

I have read that bat urine is 70% urea which would seem very strong. We believe they have been there for 6 years. - S.S. 8/12/12


It is nonsense to replace structurally sound wood because of bat urine or other surface contaminants.

What makes sense to me is to clean the area thoroughly, including HEPA vacuuming and perhaps use of a sanitizer; when the wood surfaces have dried your remediator may want to apply a sealant to give maximum odor control - it's the same process used after a post-fire remediation in a building or after a mold cleanup. More about odor control in buildings that have been peed-on or in is


If there are wood beams or members that need to be treated and that are exposed in the occupied space, you can use a clear sealant so as to maintain the natural wood look, though the surfaces may become satin or glossy in finish.

To keep bats out of the cabin you'll want to find and screen off openings through which they have been entering. Look closely, as bats can enter a home or its attic through surprisingly small passages.

Bats are important to protect and preserve insofar as possible, though I agree we don't want them inside our homes. You might want to consult with local bat experts about installing one or a few bat houses or refuges in trees nearby.

Watch out: Histoplasmosis (from bat droppings) is an infection caused by inhalation of Histoplasma capsulatum. In people with compromised immune system this can be a particularly dangerous infection, potentially fatal if not treated. See also granuloma, iritis, lung nodules. More information is


Research on Pathogenic Hazards in Bat Droppings; Skunks

Reader Question: can I use peppermint oil to repel squirrels or other animals?

Prarie dog, Guanajuato, Mexico (C) Daniel Friedman

I have heard that peppermint repels squirrels - is that true? - Anon 9/23/12


You might indeed want to try peppermint oil Anon, as a number of animal repellant products do indeed contain peppermint oil, such as some deer and cat repellants. There are mixtures for similar applications mix oils of peppermint, geranium, sage, lavender, eucalyptus, lemongrass etc.

But our research into common preparations whose effectiveness has been tested as a squirrel repellant shows some different suggestions. I've included details just below.

Watch out: some folks use mothballs as an animal repellent. Using mothballs for animal repellant is an illegal pesticide application and can cause other building odor or even health problems.

Above-left: a Mexican prarie dog (Cynomys mexicanus), a diurnal burrowing ground squirrel, and an agricultural pest in this cornfield, eyes the tourists, Guanajuato, Mexico (2015).

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There are other specific animal repellent sprays and products sold at home and garden suppliers, often targeted to specific animals: coyote urine, for example. I've also tried pouring a bit of ammonia (or bleach but never BOTH at once) onto an area on a walkway or stair where a cat kept urinating.

List of Common & Effective Squirrel & Rodent Repellant or Rodent Aversive products

For rodents, which would include squirrels, some prepared products and specialty chemicals or preparations sold as repellents include:

Return to Mold/IAQ Action Guide: What to do about mold, mildew, and other indoor allergens an environmental testing guidance website explaining what to do about mold, mildew, and other indoor allergens.


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Animal Damage at or in Buildings

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ANIMAL ENTRY POINTS in BUILDINGS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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