Can Bats do Damage to Your House?

Small Brown Bat in Attic

It’s nearing that time of the year when we see little flying guests making their way inside our homes.

While they don’t intend to be a problem, it’s easy to see how bats can become an issue if you let them take over your house.

When left unchecked, one stray bat can turn into a colony of them!

Bats can cause severe structural degeneration due to their corrosive waste.

Bat droppings often result in guano deposits that can damage and degrade the structure of your home by causing corrosion, wood decay, and stains.

While there as several other issues bats can cause as they enter your home, the main purposes of this article are to cover some of the different physical degenerations that bats can cause – let’s get to it!

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Bats Can Be Destructive

A few years back, when my grandmother was still around, we found that she had a few bats taking up shop in her chimney.

After doing a ton of first-hand research, I learned then that bats tend to travel in groups, and when there’s one bat, more are likely to follow.

In any situation dealing with bats, it’s essential to call a local pest control service to help deal with the issue. At my grandmother’s house, we found that the bats had made their way into the attic and had caused some minor damage to it.

Some of the problems that bats can cause are:

  1. Corrosion
  2. Wood Decay
  3. Waste Stains
  4. Bad Odor

Bats Can Cause Corrosion to Structures

While bats, in general, aren’t too destructive, their droppings can be over time.

Bat and bird guano have high levels of uric acid, which can erode metal and clay structures.

These acids can damage the protective patina of copper and bronze, which can jeopardize their integrity. The acids also affect the binders for stone and concrete.

Bat guano also contains high amounts of phosphate, ammonium, and potassium. These compounds have been found in various caves in which bats have taken up shelter.

Though all these minerals make for an excellent fertilizer, it becomes a problem for bricks and clay.

These minerals can cause moisture between the cracks and weaken the structures over time, causing some issues in the home.

In addition to metal and clay materials, wooden structures are also compromised by the uric acid in guano. The fibers expand and separate in response to the acid, and it makes the wood break.

In my grandmother’s attic, the bats were removed quickly, so there was minimal damage, thankfully.

However, if we would have waited some time to get rid of the bats, or perhaps didn’t know they were there – then she may have come across some issues.

First, it’s best to be preventative however you can. If bats do take up shelter in your home, acting quicker is key to successful removal.

Bat Waste Can Cause Stains

The uric acid in bat urine can also stain the walls and cause etching on polished surfaces like glass and marble even after a pest control service has come and removed the waste.

In the aftermath, it’s highly likely that you may need to repaint or replace the surface entirely. You definitely won’t appreciate bats ruining the aesthetic of your house!

Bats Can Cause Bad Odor in Your House

As with all pest waste, excessive build-up can lead to a very foul smell.

If all that guano piles up in a single room, it can affect insulation and alter the smell. Even worse, the scent permeates all over your house if left untaken care of.

If you have bats, it’s essential to take care of the issue sooner rather than later by calling in a local pest control service.

There Are Bats in My House! Why?

Small Bats in Roost in Cave

Bats are always migrating and finding areas with better food sources. If you’re wondering why they seem to be attracted to your attic, then there are several reasons.

First, it’s probably because they see possible entry holes that they can access. They could have accidentally wandered in or are intentionally looking for a place to stay for the mating season.

Another thing to consider is whether lots of bugs can be found in your attic. Bats eat insects, so it would be an ideal location for them to stay for the season.

As nocturnal animals, bats prefer the dark, so if minimal light enters your attic, then they’re more likely to stay. They also prefer warmer areas as the cold can cause them to freeze.

Naturally, bats like to stay in caves as a deep cave is likely to show little light. If you have an attic with no windows or cracks, then it could make a good home for bats to stay.

The only way that bats can enter your house is that there is a possible entry hole in your home.

How to Get Rid of Bats

The best way to get rid of bats is to make sure they don’t enter your home in the first place.

Simply put, being preventative is the best way to go, and the best way to do that? Well, we think it’s using scent! Make sure to head on over to our article about scents that bats hate to learn how to deter them!

After you’ve read that – if you have active bats in your home, you’ll need to address the problem ASAP by calling a local pest control service as soon as you know you have an issue.

That’s what we’ve done in the past, and it’s your best route.

Here are some of the ways that you can get rid of bats and prevent them in the first place:

  • Find Where They Are in Your Home
  • Check for Holes in the Occupied Area
  • Seal Small Passages
  • Call a Professional to Create a One Way Door

Find Where They Are in Your Home

The first thing to do is to see where all the bats are hiding – a lot of times you may find bats in your attic (and if you do, we have an in-depth article about how to get bats out of your attic!)

You can quickly identify where the bats are around your house by finding their guano or urine stains.

Check to see if there are windows or other small holes with scratches on them because that could be a point of entry.

Also, try listening to squeaking or scratching.

Check for Holes

Next, check to see if there are any small openings that bats can enter from.

Since bats are nocturnal, another trick you can do is wait until night time and watch where they are exiting from.

If needed, get someone to inspect your house when no visible holes can be seen.

Bats are famous for squeezing into the smallest holes, so even a hole that’s less than half an inch wide can be a point of entry.

Seal Small Passages

After all the bats are gone, you can prevent them from coming back by sealing the passage or door permanently.

For such small animals, they have a strong memory and would likely come back to your house if they found it cozy enough.

A few areas that might slip your inspection could be holes in the roof, gaps in brick walls, and loose boards. Make sure to seal these too.

You can use a sealant like caulk to repair them and to ensure that it doesn’t wear out even if it gets wet. I recommend using caulk as it should last for a good while.

Another common entry point is chimneys.

While you can’t entirely seal your chimney, what you can do is put a chimney cap over the hole. Don’t try to start a fire to smoke them out.

I wrote a guide about some of my favorite power drills for DIY projects- which includes a review of a quality caulk and a proper chimney cap that you can install on your fireplace.

You can view that guide here (like to guide).

Call a Professional to Create a One-Way Door

There are many ways that you can bat-proof your house to keep them from coming back.

You either create one-way passages or place nets to keep them from coming back.

It’s important to make an exit point rather than sealing the area entirely because there might still be bats inside the space.

You want to call a local professional for this because of the bat mating season (May to mid-August).

During bat mating season, methods of exclusion aren’t allowed to be used on bats.

If your house has bats during the mating season, your local professional may have other options for you.

If you can have this method done, then your local pest control expert will most likely place a flap on the hole or attach a passage that leads the bats out.

The flap serves as a sort of a one-way door where bats can exit from but cannot re-enter because they won’t be able to figure out how to enter again.

Eventually, the bats will stop trying to get in and fly somewhere else.

Remember, it’s important not to harm bats.

Harming bats is illegal in most states, according to the DEC.

If you have bats in your home, visit your state’s DEC webpage to find numbers for local offices to follow up on laws in your state.

Really, it’s a great thing that bats are majority protected. Bats are an essential part of our ecosystem because they eat insects.

Unfortunately, they tend to have low reproductive rates, so their population can quickly decline if they aren’t protected.

When To Get Rid Of Bats

As much as they can be a nuisance to you, the season for getting rid of bats should be taken into consideration to ensure their survivability.

One of the main reasons why bats even enter houses is because of their mating season.

It’s likely that the bats that make roosts (bat families) in your attic are mothers with pups that need a safe space.

Pups can’t fly or navigate on their own, so you need to make sure they are fully grown before releasing them.

Mating season is different per area, so go and contact your local DEC to see if the bat mating season is in effect for your area.

It’s highly recommended that you don’t get rid of them while pups are in the roost.

They’re young pups that need their mothers for survival who aren’t ready to be on their own yet.

Mother bats know exactly where they left their pups and what their cries sound like, and many will be persistent to get back to their pups.

If you have a roost in your home or a lone pup in there, you may be stuck with bats in your house for a few months during the mating season.

In this case, you’ll have to postpone your bat exclusion to after mating season.

Build a Bat House to Deter Bats from Your Home

If it’s wintertime and you saw bats in your house, you won’t be able to get rid of them at this time because of the weather.

What some people do is build a little bat house for them to roost in.

These are placed near a post or tree that’s more than 10 feet above the ground, but the most ideal seems to be around 12 feet high.

Bat houses look similar to birdhouses that are at least 2×2 feet.

They have to be sealed tight and dark because bats hate the light.

Similarly, bats want their houses to be warm, so you should place your bat house facing south for maximum sunlight during the day (so they can get nice and toasty)

Bat houses are best built near lots of plants and a water source.

This is because they get enough food from the bugs attracted to the plants and water when they get thirsty.

Though, it’s best to build houses a bit farther away from trees to keep them away from predators.

Inside the house, you’ll need to create a sort of perch for bats to hang from. They need to drop to initiate flight, so they need a bit of space inside the house.

Benefits of a Bat House at Your Home

Wooden bat box among the branches of a tree

After everything, you may be wondering why you would want bats near your house after we just talked about getting rid of them.

Well, when they’re not in your attic, they are quite helpful to have around.

For one, bats are great pest controllers.

No need for mosquito repellants with these critters eating them away (in theory).

Bats help to control the ‘corn earworm moth’ and be very helpful to farmers since this moth is known to damage crops.

Bats can help to pollinate and cultivate your garden.

You know all that phosphate, potassium, and other nutrients in guano that we mentioned earlier?

It turns out that they’re very nutritious for plants.

Guano actually helps plants convert nutrients to make them bloom and flourish.

Also, just like butterflies, bats swoop down on flowers and spread pollen everywhere.

In all, bats are good for the environment, and you can actually benefit a lot from them as long as they don’t stay inside your home.

If you’re interested in reading more about bats, I wrote an article about the interesting ways that bats give birth.

You can click here to read that.


Bird, M. I., Boobyer, E. M., Bryant, C., Lewis, H. A., Paz, V., & Stephens, W. E. (2007). A long record of environmental change from bat guano deposits in Makangit Cave, Palawan, Philippines. Earth and Environmental Science Transactions of the Royal Society of Edinburgh98(1), 59-69. 

Shahack-Gross, R., Berna, F., Karkanas, P., & Weiner, S. (2004). Bat guano and preservation of archaeological remains in cave sites. Journal of Archaeological Science31(9), 1259-1272

“Got Bats?” fs.usda.gov 


“Bat Houses.”

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