What Is Good Indoor Humidity in Summer? 30 to 50% Always!

The rule of thumb is to keep the humidity level in your house between 30 and 50%, throughout the year.

In fact, some people just like to set the humidity level at 50% on the furnace humidifier, and then forget about it altogether.

But this might not be the best thing to do. You see, allergens thrive in high humidity. For instance, dust mites will thrive in 50% humidity.

But today, we are going to find out together what the best humidity level for your home is, in the summer.

Here, I recommend that you keep the summer humidity level in your home between 30 and 45%. If the humidity level rises above 45%, it will encourage dust mites to thrive. Again, if the humidity drops below 30%, the air will dry out your floors and wooden furniture. Also, low humidity is not good for leather items

Failure to maintain the right humidity levels in the house in any season can cause serious symptoms of sleeping in dry air, asthmatic attacks, allergic attacks, and others.

In addition to the health problems of high humidity, even low humidity can harm your items and indoor plants. I guess what I am telling you here is that you need to maintain the recommended indoor humidity level.

Keep reading as we divulge more information about maintaining the right indoor humidity level.

Is 70% humidity too high for the house?

Is 70% humidity too high for the house

Well, I created a whole article about why 70 percent humidity is high outside and inside the house. So yes, 70% humidity is indeed too high for your house.

Keeping such high humidity levels in the house is a serious recipe for mold growth in the house. In fact, research shows that mold will start to grow when the humidity level is 60 percent or higher, if the temperature is right.

The indoor humidity level should never exceed 50%, and even then, this is mostly for places that experience dry summers, such as Las Vegas. In fact, on some days, you might even find it necessary to raise the humidity level to 55%, but never to 60%.

You can see just how much higher 70% humidity is as compared to the recommended maximum of 50%. Too high!

And this is too high for any part of the house. A good humidity level for the bedroom should be about 40%.

A good crawl space humidity level is 40 to 55%. Anything higher than that will spread to the rest of the house, and it will also make mold grow.

The best humidity level for summer with AC (30 to 50%)

best humidity level for summer with AC

The AC can lower humidity, but not to the recommended level. This is why your house can be really humid, even with the AC running.

Therefore, even when the AC is running, please run that dehumidifier for summer, to lower the humidity level to the recommended level.

Maintain the humidity level between 30 and 50% when the air conditioner is running. If it is higher than that, you can still run the dehumidifier at the same time.

To maintain the required air moisture levels, use a hygrometer to monitor the humidity level. That way, if it gets higher than 50 percent, you can use the dehumidifier to lower it.

Something that most people wonder about is: if the AC is running to lower the temperature, will mold still grow if the indoor temperature is high?

Of course, it will still grow. Mold can grow in the freezer, albeit slowly, but it will grow. Therefore, in your house, it will grow whether you keep the temperature low or not.

How can you control the humidity in your house in the summer?

Now that we agree that high humidity in the summer could damage your items or even worse, expose your family to symptoms of mold toxicity, you need to put it under control as fast as possible.

Here are the simplest ways to control humidity in your house in the summer:

Run a dehumidifier

This is the first and most obvious solution for high humidity in the basement, in the living room, bedroom, or any other room in the house.

You could also have a whole-house dehumidifier attached to the furnace. That way, it automatically kicks in to lower the humidity when the set parameters are exceeded.

Running a dehumidifier is not enough. You also need to know the best position for it. For instance, place the dehumidifier high above the floor and away from walls and furniture.

Make sure you buy a dehumidifier with a built-in humidistat. If it lowers the air moisture content to the set level, it will stop automatically. If the moisture content rises, the unit will start automatically.

More ventilation helps

Houses with better ventilation can disperse the damp air from their indoor space faster and allow drier air from the outdoors to come in.

However, this can be a double-edged sword since high humidity outside affects the indoor humidity.

Therefore, if you are running the dehumidifier, do not open the windows because more humid air will keep coming inside. This can get your dehumidifier running endlessly.

Only keep the windows open if it will not be counterproductive.

Install exhaust fans

Exhaust fans help to make the work of the dehumidifier easier. Usually, exhaust fans are installed in the kitchen or the bathroom. They remove the damp air outside, thus lowering the indoor humidity.

If you live in a really humid place like Seattle, installing a few exhaust fans can help a lot. You can also consider installing ventilation in utility rooms without windows.

When you use hot showers and cook in the kitchen, you generate a lot of water vapor, which raises the humidity level.

An exhaust fan for humidity installed in these two crucial places will arrest the damp air and remove it before it can spread to the rest of the house.

Control humidity in the basement and crawl spaces

For high-humidity Florida and other places, the basement can be a really humid place most of the year. And the same applies to the crawl space.

Unfortunately, the humid air cannot stay contained in these two places. Rather, it spreads to the rest of the house.

Therefore, if you are lowering humidity in the rest of the home and you have forgotten the basement, you are not safe. The humidity will still affect the rest of the house.

Once again, for the basement or crawl space, get a dehumidifier that can run 24/7, switching on and off automatically when the need arises.

So that you don’t keep emptying the dehumidifier bucket, you should get a unit that comes with a drain hose attachment.

You can get a dehumidifier with a pump too. It can dump the water it draws from the air over a long distance, including over vertical heights.

Why you need to control humidity in summer

You cannot live in your indoor spaces if you have runaway humidity. You need to bring it down in summer so that you can sleep better.

Here are some of the reasons why you need to control the air moisture level:

Prevents the growth of mold

Mold is a notorious indoor allergen. Okay, while some species are not harmful, there are dangerous types of mold.

Toxic black mold is notorious for causing health issues. As it matures, it produces mycotoxins, which cause skin reactions like itching and rashes.

They also cause runny noses and watery eyes. If you have someone with asthma in the family, they will experience even worse mold exposure symptoms.

Mold also damages clothes, shoes, furniture, carpets, walls, and ceilings. This is why you need to get the best dehumidifier for closets, to lower the humidity level in small spaces.

It prevents a musty smell 

Mold and mildew on items in the house cause a musty smell. Therefore, by preventing the growth of mold, you enhance the air quality in your home.

When the mold matures, it starts to produce a musty smell. This won’t take too long to happen. As you can see in my article on humidity and mold growth chart, mold can mature in less than a week, and start releasing spores and mycotoxins.

If you experience a musty smell, just know you have mold. You can check the carpets, walls, ceiling, basement, and under the furniture. Check the hidden spaces in the bathroom and the kitchen.

Condensation on the windows

You know how there is high humidity after rain, and you can see the condensation on the windows. This is going to happen when you have high humidity.

As the damp air comes into contact with the cold glass of the windows, it condenses, and it can start rolling down. This means the humidity is too high.

This is a clear indication that you should run the dehumidifier to remove the air moisture content.

Also read my articles on:

Dehumidifier blows cold air

Why dehumidifier blows hot air

Shark air purifier keeps shutting down

Levoit air purifier keeps shutting off

Wrapping it up

High humidity in the summer is such a big problem for many people. Not only does it cause excessive sweating, dehydration, and other health problems, but it can also cause damage to walls, books, paintings, and so on.

In fact, high humidity damages electronics too.

You need to maintain 30 to 50% humidity in all of your rooms, including the basement. That way, you prevent so many issues, including the growth of mold.