Key Points
- Ideal humidity levels in residential spaces are between 30% and 50%.
- Excess humidity can lead to health issues and structural damage to your home.
- Reduce indoor humidity by increasing ventilation, adding a vapor barrier, carefully choosing your houseplants, integrating a humidistat, and using a dehumidifier.
Dry hands. Snowy weather. Hot cocoa. These are all common winter experiences—both good and bad. However, for some people, foggy windows also make an appearance when the temperature drops. While it can be a minor annoyance, it may be a sign that the humidity levels are too high in your home (and if that’s the case, why are our hands so dry?). Unfortunately, we don’t know much about the science behind dry skin, but we do know a thing or two about home climate solutions. If you want to avoid condensation on windows, keep reading for an explanation of the causes, the warning signs of bigger problems, and the preventive strategies you can use.
Do Your Windows Cause Condensation?
Your windows aren't responsible for condensation, but they make it easy to notice moisture buildup. Your windows react the same as your bathroom mirror fogging up after a hot shower. Windows fogging up in your house doesn't make them faulty — it makes them like any other glass surface that reacts to condensate. When you see condensation on your windows, oftentimes, it means you have well-built windows with a strong seal.
What Causes Condensation?
Condensation occurs when one side of your window is much warmer than the other. The fast-moving air particles on one side touch your cold window and go through a phase change, causing the particles to become more structured. Window condensation can mean your windows are tightly sealed and preventing air leakage, which is what creates the drastic temperature difference between the inside and outside of the glass.
Exterior window condensation happens when the outside surface is lower than the dew point in the air. This situation usually occurs when the humidity levels are higher outside than inside. Summer and spring are the biggest contenders for this kind of weather, especially when you have central air or AC window units. Your air conditioning makes the air drier inside while humidity rises outside. Condensation can even happen in the fall when the temperature drops at night. If you live in a climate where it's generally warmer and humid throughout the year, exterior window moisture might be frequent. The sun will typically dry up any condensation on your windows when this happens, but you can also apply a water repellent to keep your windows clear.
Interior window condensation happens when the humidity levels inside your home are higher than the levels outside. This event usually occurs in the winter when the air outside is dry, but you can also raise indoor humidity levels with showering, laundry, and cooking. Other causes of interior window condensation include:
- Closed shades or drapes
- Low air circulation inside your home
- Poor ventilation in high humidity areas like kitchens and bathrooms
- Large collections of houseplants or woodpiles stored inside
Sometimes, window condensation happens between the glass panels. Unlike exterior and interior condensation, this scenario is a sealing problem. Dual-pane and triple-pane windows are modern designs used to increase energy efficiency and reduce condensation, but a faulty seal can make it easy for moisture to get in between the panes. If this is happening in your home, contact a window installation professional.
Is Condensation on Windows Bad?
Condensation on its own isn't bad, but it can be an indicator of a bigger problem. You don’t need to worry about occasional moisture that appears in winter. However, consistent high moisture might make your home climate uncomfortable. Excess humidity can make it harder to sleep, cause you to sweat without much physical activity, and lead to frequent dehydration. The EPA recommends keeping humidity levels below 60% in your home. The ideal range is 30% to 50%, though it may fall lower in the winter months. Steam radiators, plants, using the dryer, and showers can raise the humidity levels in your home, so be aware when using them. Taking preventative steps helps maintain healthy home humidity levels, especially if your home is prone to moisture creation.
Ways to mitigate condensation accumulation include:
- Keeping the temperature consistent
- Avoid drying clothing over a radiator
- Limiting dryer usage. Use a clothesline when possible
- Checking your dryer for proper ventilation
- Running your extractor fan while you cook
- Maintaining your extractor fans for strong airflow
- Moving furniture away from the wall to prevent moisture transfer from outside
Even with these preventive measures, you can still have frequent condensation issues if there’s a larger issue with your home. If you try the above tips and still notice excess window condensation, it's time to call in a professional.
What Issues Does Indoor Humidity Cause?
Beyond excess sweating, high indoor humidity levels can cause health issues for your family and structural problems for your house. One of the most common problems with high humidity is mold development. Mold is a natural occurrence, and it's not possible to eliminate all the mold in your house. Normally, this wouldn’t cause much of an issue unless a member of your household is sensitive to mold spores. However, excess moisture exacerbates the issue, making it dangerous for the whole house. If you have mold in your home and it makes contact with a damp spot, it will spread its spores, and they'll start to grow. Sometimes, mold can develop near your HVAC system's intake. When this happens, the mold can spread quickly through your vents to other parts of your home. This spread can also occur when the insulation inside your air ducts gets wet, highlighting the importance of AC mold prevention.
Health Issues
Mold spores can produce allergens, irritants, and even toxins that can cause health problems when inhaled or touched. Some people may have minimal reactions to mold spores, but those with allergies may experience hay fever symptoms like red eyes, sneezing, an itchy nose, and a skin rash. For people with asthma, mold can cause sudden asthma attacks. Even in nonallergic people, mold can irritate noses, eyes, throats, skin, and lungs. For people with a history of allergies, it might be hard to notice mold-related symptoms, especially if they're allergic to common substances like dust and pollen. If you're someone who rarely experiences these irritations and you suddenly notice them, you should investigate for mold as soon as possible.
Prolonged exposure to high humidity has also been linked to higher rates of respiratory infections and absenteeism from school or work due to sickness. The Centers for Disease Control and Prevention (CDC) has found that people who spend time in damp buildings are more likely to experience a range of health problems, including:
- Respiratory symptoms in the nose, throat and lungs
- Allergic rhinitis, also called hay fever
- Respiratory infections
- Worsening or development of asthma
- Bronchitis
- Hypersensitivity pneumonitis, a rare lung disease
- Eczema
Structural and Property Damage
While excess humidity can be tough on the body, it can also wreak havoc on your house and the things inside. Humidity won't cause water damage on its own, but it can make leaky pipes and wet spots on your ceiling worse. When there's more moisture in the air, it's harder for wet spots to evaporate. You might notice during humid summer months that the towels in your bathroom take much longer to dry, or your hair stays wet for longer after a shower. If you have a leak in your ceiling from rainwater or plumbing problems, that moisture can sit for much longer, wearing away at drywall and joists. Fortunately, it would take some perfectly timed scenarios for this to happen. Older homes may be more at risk for plumbing issues, leaks, and high humidity, so this situation isn't unheard of. But if you take care of humidity levels before disaster strikes, this sort of property damage is less likely to occur.
Mold feeds on dead or dying organic materials, like wood, fabrics, paper, and some glues. You can find these materials all over your home, and when mold spreads, it eats away at your belongings. With enough time, mold can damage your wallpaper, your furniture, and even the drywall. Excess mold growth also means the environment is suited for decay fungi—mold's much more destructive cousin. While mold tends to build up on surfaces, decay fungi work into the core of your wooden joists and support beams, causing rot. This sort of structural damage can lead to expensive repairs, and it may even make your house unsafe to live in.
How Do You Avoid Condensation and Reduce Indoor Humidity?
Reducing indoor humidity is essential. Thankfully, there are several strategies and tools you can use to tackle moisture that will keep your loved ones and home in good shape:
1. Increase Ventilation
Ventilation is the key to reducing humidity levels. In the kitchen, your extractor fan improves airflow from your stove. In your bathroom, a vent prevents condensation on the mirror and walls. Your dryer also has a vent to release moisture. You may consider installing a whole-house ventilation system if you don't already have one. Newer homes use a range of technologies to keep the space airtight, so these large-scale ventilation systems are essential for eliminating excess moisture.
2. Be Mindful of Humid Rooms
Kitchens, bathrooms, and laundry areas are all prone to humidity. In your kitchen, tasks like boiling water, making coffee, and cooking on the stovetop create humidity. Covering your boiling water can contain excess moisture and make your water heat up faster. Limiting your shower time in the bathroom can help reduce moisture buildup. Keep your vent running for the 15 minutes following your shower, and make sure to use a large, absorbent bath mat. As an added humidity guard, keep the doors to your kitchen and bathroom closed during moisture-building activities. Doing so will prevent the moisture from spreading to other rooms in your home.
3. Add a Vapor Barrier to Your Crawl Space
Your home is at a higher risk of excess humidity if you have a basement or crawl space. Building codes require insulation in these areas, which is ideal for energy efficiency but can cause moisture issues. Insulation is usually applied before the concrete is completely dry. Concrete is highly porous and can hold onto moisture for years. Installing vapor barriers can prevent moisture from entering your crawl space. These membranes sit across your soil and prevent the soil's moisture from traveling to your foundation. While these barriers can't stop water runoff from entering your crawl space, they can reduce humidity buildup.
4. Choose Houseplants With Care
If you're already living in a humid area, your plants can make the problem worse. Tropical plants like bamboo palms, monstera, and ginger release more vapor into the air than other greenery. If you still want to decorate your home with plants, try drier species like cacti, spider plants, and tillandsia.
5. Regulate Levels With a Humidistat
Monitor your humidity levels with a humidistat. An HVAC professional can install one for you, and you can get a reading of humidity levels in the area. If you find your levels are consistently high, implement more preventative strategies or call a professional.
6. Use a Dehumidifier
You might be doing everything you can to control humidity levels, but they're still higher than the recommended range. In this case, try using a dehumidifier. One or more dehumidifiers can keep your levels in check along with other moisture-reducing tactics. Plus, these machines often reduce dust buildup, making your chore workload a little smaller. Options like the AprilAire E080 Dehumidifier can handle the excess moisture in most spaces, offering you a single, whole-home condensation mitigation solution.
Shop Ventilation & Dehumidification Products with IWAE
Ventilation and dehumidification are essential for your home if you see frequent window condensation. At IWAE, we carry reliable products at reasonable prices. Learn more about our dehumidifiers and ventilation equipment today. If you need help finding the right equipment for your home, get in touch with our team to discuss your options.
