Whether it’s the middle of a dry winter, or a humid summer day after a heavy rainfall, the amount of moisture in your home’s indoor air can have a significant impact on your comfort, health, and even the condition of your property. While many homeowners focus on temperatures, humidity is often overlooked despite playing an equally important role in creating a healthy indoor environment.  

When indoor humidity levels are too high or too low, you may begin noticing everything from dry skin and irritated sinuses to condensation on windows, musty odours, or even mold growth. Understanding how humidity affects your home is the first step toward protecting both your family’s health and your property.  

What is Humidity and What is the Ideal Indoor Level?

Humidity refers to the amount of water vapour that is present in the air. When discussing indoor environments specifically, we often refer to relative humidity (RH), which measures the amount of moisture in the air compared to the maximum amount the air can hold at a given temperature.  

For most homes, the ideal indoor relative humidity level is between 30% and 50%

Keeping humidity in this range can help create a more comfortable living space, while also reducing the risk of mold growth, structural damage, and respiratory health issues.  

Humidity levels also naturally fluctuate throughout the year. Here are some things to keep in mind for the different seasons:

• Winter: Aim for humidity levels of 30% to 40% to reduce condensation buildup on window, while preventing overly dry air.  

• Summer: Keep humidity below 50% to discourage excess moisture and mold growth.  

Using a simple hygrometer can help you monitor humidity levels consistently thoroughout your home.  

How Can You Tell if Humidity is Too Low?

Low humidity is more common during the winter months, especially when furnaces are continually heating indoor air. Although dry air may not seem like a major concern, it can affect both your health and your home over time.  

Signs of Low Indoor Humidity

If your indoor air has low levels of humidity, you may notice:

• Dry and itchy skin  

• Chapped lips

• Irritated or dry eyes  

• Frequent nose bleeds

• A dry, scratchy throat or persistent cough  

• Increased static electricity  

• Cracks in hardwood flooring or furniture

• Shrinking or warping wood trim  

• Houseplants drying out quickly

How Low Humidity Affects Your Health

When indoor air becomes too dry it can dry out your nose, throat, and respiratory passages. These tissues normally act as a natural barrier against bacteria and viruses. When they become too dry and irritated, they are less effective at filtering airborne contaminants, potentially making you more susceptible to respiratory illnesses.  

For individuals with asthma or other respiratory conditions dry indoor air may worsen symptoms, while also causing general discomfort, headaches, and poor sleep quality.  

How Low Humidity Affects Your Home

Your home can also suffer from prolonged dry conditions. Wood naturally expands and contracts with changes in moisture. Extended periods of low humidity can lead to:

• Cracking in hardwood flooring and gaps between floorboards

• Splitting furniture

• Separated trim and mouldings  

• Damage to wooden musical instruments and antiques  

Maintaining proper humidity levels helps preserve materials and reduces unnecessary wear overtime.  

What Happens When Indoor Humidity is Too High?

Excess humidity indoors introduces an entirely different set of concerns. When too much moisture remains trapped indoors, it creates ideal conditions for mold, bacteria, and dust mites to thrive.  

Signs of High Indoor Humidity

If your indoor air has high levels of humidity, some warning signs can include:

• Condensation on windows

• A damp and sticky feeling indoors  

• Musty or earthy odours  

• Persistent dampness in basements

• Water stains on ceilings or walls

• Peeling paint or wallpaper

• Increase of insects

If left unaddressed, excess humidity can lead to larger indoor air quality problems and mold growth.  

How Does High Humidity Affect Health?

High humidity indoors can negatively impact your indoor air quality by creating the perfect environment for biological contaminates to grow. This can include mold, mildew, dust mites, and bacteria.  

Exposure to these contaminants, especially long term, may contribute to:

• Increased allergy symptoms

• Asthmas flare-ups

• Respiratory irritation

• Persistent coughing or sneezing

• Eye, nose, and throat irritation

For individuals with allergies, asthma, or weakened immune systems, maintaining proper humidity levels is especially important for health.  

How Does High Humidity Affect Your Home?

Moisture doesn’t just affect your air; it can also gradually damage many builing materials throughout your home.  

High humidity levels can contribute to:

• Mold growth behind walls, under flooring, and inside attics

• Rotting wood framing

• Damages drywall

• Warped flooring

• Insulation losing effectiveness

• Peeling paint  

• Corrosion on metal fixtures

Many of these problems go unnoticed at first and become much more costly to repair down the road if the excess moisture, and the source of the problem, are not addressed.  

How Can You Manage Indoor Humidity?

Fortunately, maintaining healthy indoor humidity is often achievable with a few simple habits. Here are some of the best ways to control indoor moisture include:

• Use a hygrometer to monitor humidity levels

• Run an exhaust fan in the bathroom while showering or in the kitchen during and after cooking

• Repair any leaks from pipes or your roof

• Ensure your home has proper ventilation, especially in attics and crawl spaces

• Use a dehumidifier in damp areas of your house, such as in the basement

• Add moisture to the air with a humidifier during extremely dry winters  

• Maintain your HVAC system and replace filters regularly  

• Ensure your dryer vents outdoors and isn’t blocked

• Keep gutters and downspouts clear to move water away from your home’s foundation

Consistently monitoring your humidity levels can help you catch a small issue before it develops into a larger moisture problem.  

When Should You Call a Professional?

If you’ve noticed a persistent earthy odour, recurring condensation, humidity levels that remain difficult to control, or even visible mold growth, it may be a sign that there is a larger underlying issue. Hidden water damage, poor ventilation, or excess moisture behind walls can often go unnoticed for quite some time without a professional inspection.  

Our team at got mold?™ can help identify the source of the moisture problem, assess indoor air quality concerns, and determine whether mold or hidden water damage is affecting your home. Addressing these issues early can help prevent more costly and timely repairs in the future, while also protecting your overall health.  

Humidity is something that every homeowner experiences, however, many don’t realize how much of an influence it actually has on your indoor air. Whether your home is too dry in the colder winter months, or too damp in the summer heat, maintaining balanced humidity levels throughout the year is one of the simplest ways to improve comfort, protect your home, and reduce moisture related risks.