What do humidity percentages mean? You Should Know This

A lot of people use humidifiers or dehumidifiers to control the moisture percentage in our homes so that we can be comfortable. Air contains some water. There shouldn’t be too much or too little water in the air to keep our home comfortable.

Dehumidifiers (such as air conditioners) normally soak up the extra humidity from the air and allow us to get a good night’s sleep. Even when we are traveling to our respective workplaces, we turn on the AC in our cars so that we do not sweat due to excess humidity inside the car. If the air is too dry, we can use a humidifier. These are often used in the wintertime but it depends on your local climate as well.


Experts tell us to maintain the humidity level at around 30%, however, you must have wondered what it exactly means. Today, let’s explore the facts together. To know how we can measure this, we have to take a look at humidity and relative humidity.

The difference between humidity and relative humidity: types of humidity

If we go back to our school days, we can recollect that the definition of humidity is the concentration of water vapor in the air. Various percentages of humidity in the atmosphere cause dew, fog, or precipitation. There is a limit to how much water can be in the air.

Absolute humidity: what is it?

The total mass of water vapor present in a respective area is known as absolute humidity. Absolute humidity looks at how much water droplets can be present in the air. It doesn’t consider how much water the air can hold. It is expressed as the volume of water vapor (mH2O).

It is more a theoretical measurement as the temperature affects how much moisture the air can hold. It doesn’t take every relevant item or variable into account. For this reason, it is more used by scientists than plumbers or AC techs.

What is relative humidity?

Relative humidity is the quantity of water vapor in the air versus how much water the air can hold. Basically, it is the volume of water vapor present in the air compared to the maximum of water in the air. It is measured as a percentage (%) of the quantity needed to attain saturation. This means that the air would not be able to absorb any more water if it is at 100%.

Relative humidity takes temperature into account. In warmer weather, it can absorb more water than in colder weather. In essence, it looks at the current situation in a room to determine how much humidity should be present. For this reason, relative humidity is more practical and allows us to adjust the settings on our humidifiers and dehumidifiers.

You can often notice humidity on a window as there is a mist or water droplets on them.

There are devices and sensors that make it easy to measure relative humidity. This makes it easy to see if there is a problem and adjust the humidity in a room. This is done by adding or removing water vapor from the air. The relative humidity is used to determine the humidity percentage in a room.

Some people argue that relative humidity is not easy to work with and that we should use the dew point as this indicates when grass gets wet and is more practical. This is the point that the air is not able to hold any water anymore.

Ideal relative humidity: what is it?

If you have bought a humidifier and are wondering what the ideal setting will be, then according to plumbers, the ideal RH for comfortable indoors is somewhere between 30-50%. In layman’s terms, it means that the air in that particular atmosphere holds between 30-50% of the maximum amount of moisture it is capable of containing.

Why the humidity percentage is important in a house: what does 80% or 100% mean?

This might sound absurd, however, it is true. When the humidity inside the home is too high, it can even do damage to the property. The excess moisture can give birth to mold and create a conducive environment for it to procreate and survive. Research done by the Building Science Corporation found that humidity of 70% or higher can cause serious damage to the building and walls.

Let’s see how

1. Too much moisture

Damp places in the home are perfect for the growth of mold and mildew. Have you ever wondered why black or dark green mold forms in the bathroom and near the cemented kitchen sink?

Have you ever noticed closely the grey patches on your shower curtains or bathroom walls? They are mildew that grows in humid conditions. If you do not get rid of this mold and mildew, it will start chewing on the shower curtains, rugs, books, wallpaper, etc. in the bathroom.

It also impacts the structural integrity of the house by weakening the window and door fixtures, walls, and ceilings. Deep cleaning your bathrooms periodically should take care of the problems caused by the growth of mold and mildew. You can also add more ventilation or a window to adjust the humidity levels after a shower. Sometimes the local plumbing code even requires that you do this in a bathroom.

Exterior walls face the wrath of the weather, and if not maintained properly, the humidity will cause damage to the paint and eventually erode the cement. Hence, it is important to use good quality all-weather paint to safeguard the external and internal walls and repaint them periodically.

To safeguard the internal walls, one should invest in an air conditioner or dehumidifier and keep the humidity under control. It will not only be comfortable for the inhabitants of the home, but also for the wall paint.

Furniture will start to develop stains and growth if there is excess humidity in the atmosphere. The wood will start swelling and will get deformed soon. If you have wooden floors, you need to be all the more careful. Even seasoned wood starts drinking the moisture and starts swelling. Over a period of time, it will start rotting and no amount of curing will be effective.

You can add plastic to the crawlspace or add ventilators and dehumidifiers to lower the amount of humidity in a house. Each house is unique so you will have to check with your installer to see what is possible for your home.

2. Too little moisture in the air

If there is too little moisture in the air, it can be uncomfortable to be in a room. This can happen during the wintertime or when the air in a room hasn’t been refreshed for a while. Some climates also have drier air.

There are cheap sensors that allow you to monitor the humidity percentage. This allows you to take action if needed.

A humidifier can be used to spread moisture in the air. There are different principles that they work on (from heat to vibration). It is important that you clean your humidifier often as can spread dirt over your house if the filter and water reservoir are not properly maintained. Humidifiers often have sensors that measure the relative humidity in a room. This allows them to activate when the humidity percentage is too low. They shouldn’t be active all the time as this can indicate a problem with your device.

Conclusion: what do humidity percentages mean?

Plumbers and AC techs spend a lot of time making sure that homes are comfortable. The relative humidity in the bathroom, kitchen, and sleeping room is a big part of this. If this isn’t correct, the house might be uncomfortable. Too much moisture in the air can lead to mold and mildew. These can be dangerous and should be removed as soon as possible.

Not enough moisture in the air can make it feel dry. For this reason, it is important that you discuss with your plumber how you will manage the humidity in the air. This can be done by adding ventilation, a humidifier, or a dehumidifier. Your needs will depend on the climate and personal preferences.

The humidity percentage indicates how much moisture there is in the air. It is a great way to objectively determine what needs to happen with the air in a house. This allows plumbers to offer suggestions. All these systems need maintenance and cost money to install so it is important to find the best solution for your home. Sensors can help to check how the humidity percentage evolves over time and can activate your humidifier or dehumidifier.

If you have a humidifier, it is important that you clean the filter often if you want to keep the humidity level in the desired range.