does humidity rise or fall in a room

Does Humidity Rise or Fall in a Room? An appropriate level of humidity is essential for a pleasant indoor climate.

We all know that don’t we?

It is vital because of a number of health and structural issues that can arise from either too much or too little humidity.

But have you ever pondered does humidity rise or fall in a house? Well, the humidity levels can fluctuate based on many factors. 

Humidity can rise or fall in a room based on various factors, including ventilation, temperature, building materials, and human activity

Does Humidity Rise or Fall in a Room?

room humidity

The most fascinating thing about humidity is that it changes based on many variables.

But, does humidity sink or rise in a house? Well, it can do both!

When the air in a room has too much moisture, the water vapor saturates the air making humidity levels go up.

It can result in issues with condensation, dampness and various molds.

Moisture always moves from areas of high temperature and moisture to lower areas, which is how water vapor can move throughout the structure of a house.

As it is carried in the air it defies gravity, rising and spreading as it is forced through gaps in the walls.  But, there are many factors at play here. 

Basic Factors Affecting the Rise and Fall of Humidity

factors affecting rise and fall of humidity

The three main factors affecting the humidity levels in a room include:

  • Building materials
  • Ventilation
  • Temperature

Humidity levels will change if the construction materials fail to absorb water and there is poor ventilation.

Similarly, activities that raise the temperature and water availability will also affect humidity.

Temperature is the biggest contributing factor. A temperature rises, the percentage of water vapor in the air rises.

The humidity will fall if a door is opened but rise if someone showers.

Since dry air holds heat inefficiently, there has to be some moisture in a room to warm it. 

Factors that Contribute to High Humidity Levels

factors affecting rise and fall of humidity

Speaking of humidity rising in your room or property, you will have to consider the following factors: 

Low Ventilation and Rising Humidity Levels

Ventilation is essential to avoid dew-like condensation forming on cooler surfaces.

Whilst an air-tight room voids the effects of outside weather, conditions inside the room cause humidity levels to rise. 

As well as certain construction materials, basements and crawlspaces attract moisture around a home.

In a room with poor ventilation, people and their activities can contribute to rising humidity. 

Human Factor and Rising Humidity in a Room

human factor and rising humidity in room

The occupants in your home exhale water vapor as a byproduct of their metabolic process. 

This adds as much as 2 litres (4.22 pints) per day for a family of four and even their sweat adds to the amount of water in the air.

Other sources of increasing humidity are water-based activities such as:

  • Bathing
  • Cooking
  • Floor washing
  • Clothes drying
  • Watering houseplants
  • Poor maintenance causing leaks 

The Effects of Rising Humidity in a Room

With humidity levels going up, the room feels uncomfortable causing its occupants to become dehydrated and feel sticky.

This is mainly because the sweat fails to evaporate, and the air becomes denser, making it harder to breathe.

effects of rising humidity in a room

As the moist air moves attempting to find equilibrium by spreading out evenly through the room, condensation forms on any cooler surface particularly around the windows and on outside walls.

The warmth and moisture are ideal growing conditions for bacteria, spores and dust mites, making the environment unhealthy. 

Natural materials, such as leather develop molds and clothing smells musty, wood swells and rots and metal fittings like door handles tarnish and rust. 

Things to Do to Lower Rising Humidity in a Room

ways to lower rising humidity in room

When you notice humidity rising in your room, you can always try ways to change the conditions and lower humidity.

Some options include the following:

  • Limit the number of water-based activities in a room and use correctly vented appliances.
  • Add ventilation by opening a window so dense air can escape.
  • Consider using a fan or humidifier to improve ventilation.
  • Place products to absorb water vapor like charcoal, salt or even cat litter in the room.
  • Place leafy houseplants that take their water in directly from the air around the room.
Fact: Certain plants including the Boston and Lady ferns, English and Algerian ivies, Areca palms, rubber and snake plants can help lower humidity in a room. 

Factors that Contribute to Low Humidity Levels in a Room

factors contributing to low humidity room level

Just like high humidity, low humidity can also cause all sorts of problems. Low humidity is the result of low temperature.

It could be because colder air:

  • Forces its way in from the outside.
  • Pushes warm air out.
  • Artificially lowered using fans or air conditioning.  

The main source of low humidity in a room is the cold air getting in from outside.

Evaporation has slowed so this air holds less water vapor than it can. Its density is lower than that inside the warmer room.

To equalize its temperature, pressure and density, the air pushes in through any opening, felt as draughts as the smallest of gaps in the building’s structure give way to the pushing air.

Fact:  The easiest way to control humidity is with a humidifier but when left to run in an airtight building or room, these systems reduce humidity levels too far. 

The Effects of Humidity Falling in a Room

effects of humidity falling in a room

Low humidity can be as uncomfortable and as harmful as high.

Breathing dry air for long periods irritates the body’s mucous membranes.

This results in dry eyes as tears evaporate, and sore throats and noses as passageways dry out and feel congested.

Without the protection provided by a rich layer of mucous, the body becomes more vulnerable to airborne bacteria and viruses.

Skin feels taut as its surface layers dry out forming flaky itchy patches. 

Fact: With falling humidity, the skin is forced to pull moisture out of its lower layers to compensate, creating the painful cracks of eczema. 

Overcoming Fall Humidity in a Room

There are simple ways to make a room feel more comfortable by increasing the percentage of water vapor in the air.

You could:

  • Place bowls of water around the room.
  • Take a shower or bath.
  • Water your houseplants.
  • Boil some water.
  • Air dry your laundry.
  • Use a humidifier or vaporizer. 

Maintaining Optimal Humidity Levels in a Room

maintaining optimal humidity levels in a room

Maintaining optimal humidity levels in a room is about managing the amount of water vapor in the air.

For most life, the optimal conditions are within a very small range.

Indoors, humidity levels are comfortable between 40% and 50% although recent research suggests most buildings can cope with up to 60%.

Keep in mind that indoor levels will fluctuate with activity and the number of occupants.

It will also fluctuate according to the temperatures outside, being subject to hourly, daily and seasonal variation. 

Understanding a Bit about Optimal Humidity Levels

Knowing the optimal percentage for indoor humidity as temperatures rise and fall can help manage the risks of illness, infestation and damage.

Outdoor Temperatures 0FarenheitOptimal Percentage Indoor Humidity
500 plus45% maximum
250 – 50040%
0 – 25030 – 40%
-200 to 020 – 30%
Below -20015 – 20%
optimal humidity levels using dehumidifier

Using a dehumidifier in summer and a humidifier in winter can help maintain the humidity in a home.

Similarly, you should take steps to reduce the amount of water vapor available.

This could mean changing habits such as:

  • Taking cooler shorter showers
  • Opening windows
  • Using lids on the saucepan
  • Turning on the extractor fan when cooking

It is also sensible to repair cracks in the building structure, especially those around windows, crawl spaces, and roofs.

Homeowners need to aim towards keeping levels balanced across all the rooms of the house.

Fact: Humidity can be measured with a hygrometer, which needs to be located carefully to count the number of water vapor molecules suspended in the air. 


Does humidity rise or fall in a room? Humidity in a room can rise or fall based on many factors.

Knowing and keeping a room at just the right humidity level is essential for comfort and health.

Humidity is affected not just by environmental variables like temperature and ventilation and building materials but also by human actions and upkeep.

Finding the sweet spot between too much and too little humidity is possible with the help of a hygrometer and some careful planning.