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Do Birdhouses Need Ventilation? (Or Is the Entrance Hole Enough?)

Do Birdhouses Need Ventilation? (Or Is the Entrance Hole Enough?)

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Here’s something you may not know: a bird’s body is about 5℉ warmer than a human’s.

That means birds get hotter faster than us, and their bodies emit heat to the surroundings. Imagine cramming some birds in a birdhouse with no means of ventilation. That would be ugly, wouldn’t it?

This brings us to the question, do birdhouses need ventilation?

Well, proper ventilation is one of the many things that make for a safe birdhouse. This can be achieved through the house’s entrance hole in cold climates. However, if you live in a warm climate, a few ventilation holes are essential to make the birdhouse both comfortable and safe.

Read on to find out how to build or customize a birdhouse to have enough ventilation, so the guest birds can thrive inside.

Why Do Birdhouses Need Ventilation Holes?

Birds have a higher core body temperature than us humans, as theirs is about 102-109℉. This means that their bodies are much warmer than the ambient temperature, so they emit a lot of heat to their surroundings.

In an enclosed space like a birdhouse, this heat can build up, especially if the weather is warm in the spring or summer and there’s a batch of younglings inside. With nowhere to go, the small space of the birdhouse becomes a bit like an oven because of all the trapped heat.

You might be wondering why the heat can’t escape from the entrance hole. Well, some of it does, but unless there’s an opposite hole to the entrance, there’s no cross breeze.

Imagine sitting in a car with all the windows closed. If you crack open one of them, you get a little bit of ventilation. However, if you crack open the opposite window, too, you really feel the breeze come through.

This is the exact same concept as ventilation holes; they provide an exit for the warm air trapped inside to maintain that draft of fresh, cool air coming through the birdhouse.

Where Should I Place the Birdhouse Ventilation Holes?

Ventilation holes should always be high up in the birdhouse walls but not through the ceiling to prevent rainwater from flooding the inside. Hot air travels upwards due to its convection properties, so the higher up, the better.

You can place the ventilation holes right under the birdhouse’s roof. The holes don’t have to be huge; just a ¼ or even an ⅛ of an inch is enough.

If you’re building the birdhouse from scratch, or if you get a premade birdhouse that has no ventilation holes, it’s pretty easy to get it done. All you need to drill the holes are:

  • A drill
  • A ¼ or an ⅛” spade drill bit


  1. Decide how many holes you want to place per wall—one or two should be enough
  2. Tip the birdhouse to its side and drill the holes
  3. Remove any excess wood shavings from the inside of the house
  4. Clean the house with a safe disinfectant and put it up

If you’re letting your children join in the fun of building the birdhouse, you can make the holes using a hand drill or by hammering in a large nail and then taking it out. No power tools are needed!

Now that we tackled ventilation, what about drainage holes?

Do Birdhouses Need Drainage Holes?

Yes, birdhouses benefit tremendously from draining holes. If water gets inside the birdhouse, the holes will provide a direct way for the moisture to escape without causing much damage.

Most birdhouses are made of bare wood that’s only painted on the outside. So, if water seeps in, it can start rotting the wood, causing mold and mildew buildup.

There’s also the danger of a flash flood drowning baby birds if the water level inside the birdhouse rises. That’s why some strategically-placed drainage holes are necessary.

How to Add Drainage Holes to a Birdhouse?

Drainage holes are exactly like ventilation holes; the only difference is their positioning. Most birdhouses come with a sliding trap door; you can make the holes in that door.

If there’s no such door in the birdhouse you have, just flip it upside down and make drainage holes in the four corners.

Just be careful not to widen the holes too much, or else some tiny birds’ eggs might fall through. Also, avoid putting the holes too close to the center of the floor, as this might make the birds feel less safe inside.

After a few seasons, if you notice the trap door getting worn or having mold or mildew growth, discard it after making a replacement. Just don’t forget to drill drainage holes in the new door as well!

What Are Other Ways to Ensure the Safety of a Birdhouse?

Ventilation and drainage are just a couple of aspects that can make a birdhouse safe for nesting birds. There are many other ways you can make sure the birdhouses you’re setting up are up to code.

Construction Materials

You should avoid birdhouses made of metal as they are highly heat-conductive. They’ll basically turn into tiny ovens in the summer and refrigerators if the weather is cool.

Thankfully, most birdhouses are made of wood, but the wood type is essential for the safety of the nesting birds.

Untreated wood that has no strong scents is the standard here, as it has no toxic chemicals or unpleasant, strong odors that can put birds off nesting inside.

Hardwoods are preferable to softwoods since they can handle a variety of weather conditions and are more insulated from the outside cold or heat. They also tend to remain in better shape over the years, allowing for multiple uses.

Painting the birdhouse might be a fun activity, but unfortunately, it might not be the best direction to take.

Aside from vibrant colors attracting predators, the paints can also be toxic to the birds if they peck and swallow wood bits. Dark colors can also absorb unnecessary heat, making the birdhouse unbearable in the summer.

A clear, weather-proofing coating, like PolyWhey, can provide the birdhouse with enough protection against the elements while maintaining heat reflectivity.

Roof Overhang

This part ties in with drainage since enough roof overhang can prevent rainwater from flooding the birdhouse inside. It can also provide shade to the inside of the birdhouse in the summer months.

A roof overhang that’s one inch from the birdhouse body is standard. However, you should increase the overhang in length the larger the entrance hole is. This is to minimize incoming moisture and protect the birdhouse from mold and mildew.


If you want to set up the birdhouses to take a look at the birds inside every now and then, it’s important to have a direct way to access the birdhouse without disturbing the birds or the nest.

The most accessible, least intrusive way of watching the birds is through the top. Birdhouses with removable roofs are available, and they make the process less frightening for the birds.

It’s also a great way of maintaining the cleanliness of the birdhouse between seasons, so no scents or bits of last year’s nest remain inside. Birds prefer to nest in a clean cavity.

Predator Proofing

Birds, especially baby birds, can be preyed on by many different predators. You can expect pets, rats, squirrels, raccoons, and birds of prey to come looking for food inside a birdhouse.

That’s why it’s vital to place the birdhouse away from any branches that an animal can climb. There’s also no need for a perch in front of the birdhouse, as the birds don’t need it, but a predator might use it to gain footing.

And as we mentioned earlier, you should steer clear of bright colors for birdhouse paint since they attract the attention of many animals.


Where you place the birdhouses is imperative to whether or not the birds can nest and thrive inside.

If the birdhouse is in a place with a lot of direct sunlight or wind, the birds probably won’t choose to live there.

A place that gets full or partial shade, as well as being relatively obscured from the view of predators, is the perfect position for a birdhouse.

You can also tilt the birdhouse slightly forward so rain can’t get in through the entrance hole and pool inside. This, alongside the drainage holes, will be enough to keep the birdhouse safe and dry.

Final Thoughts

Building and setting up birdhouses can be a fun activity for the whole family. However, before you start a production line for the next nesting season, you should ask: “Do birdhouses need ventilation?”

If you live somewhere with cool summers, then the entrance hole can provide enough ventilation, but for warmer climates, ventilation holes are a must.

Just make sure you’re placing them higher up in the birdhouse walls to allow hot air to escape. As for drainage, a few holes at the corners of the birdhouse should be enough.

You should also factor in different aspects of birdhouse safety when you’re putting them up. Things like construction materials, roof overhang, accessibility, predator proofing, and the position of the birdhouse make a huge difference in the safety and comfort of your future guests.


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