Why Is My Basement So Humid?

Have you ever stepped into your basement and felt like you were entering a tropical rainforest? Milwaukee, WI is far from the tropics, and this damp air can cause more problems than you may realize. If you notice excessive humidity in your basement, you likely need the help of a seasoned professional. The team at Everdry Waterproofing of Wisconsin can take care of basement humidity quickly and efficiently, as well as explain why basements are so humid. Here’s everything you need to know about humidity and how to take care of it.

Are All Basements Humid?

While it’s true that basements tend to be more prone to humidity compared to other areas of the house, basements aren’t inherently humid. Factors such as climate, construction, and moisture control measures can influence the humidity levels in basements. Some basements may naturally have lower humidity, while others may require additional interventions to manage and reduce humidity levels effectively.

Causes of Humid Basements

The first step to addressing the problem is understanding why it occurs. So, why are basements humid? The answer depends on your specific circumstances, such as your home’s foundation, ventilation, and the current weather. Here are some common culprits behind a humid basement:

Poor Ventilation

Poor ventilation is likely the reason your basement is so humid. Basements often lack windows or doors to allow natural airflow, meaning moisture becomes trapped. When there’s no breeze or mechanical system to circulate the air, humidity levels rise. Over time, this trapped moisture can condense on cold surfaces like concrete walls and floors, leading to problems like damp patches, mold, and mildew. Without an escape route for the moisture, your basement becomes a breeding ground for musty odors and allergens.

Groundwater and Foundation Issues

Your basement’s design might be contributing to humidity issues in a big way, especially if there are groundwater or foundation problems. When rainwater or groundwater seeps through cracks in your foundation, it can lead to elevated moisture levels. Hydrostatic pressure, which builds up as water in the soil pushes against your foundation wall, exacerbates this issue. Over time, even well-built foundations can develop tiny cracks or pores that allow water seepage.

High Outdoor Humidity

Sometimes, your basement isn’t the problem—it’s the climate you live in. If Milwaukee is having a particularly humid summer, moisture from the outdoors can easily find its way inside. Basements are naturally cool, which makes them more likely to attract condensation when warm, humid air enters.

Appliances and Plumbing

Your home’s appliances and systems might be adding to the problem. Water heaters, washing machines, or sump pumps can release moisture into the air. Dripping or leaking pipes can also increase the water levels in your basement, raising relative humidity. Another hidden culprit? Dryer vents. If improperly installed or not maintained, these vents can release warm, moist air into your basement instead of sending it outdoors.

Broken Gutters or Poor Drainage

Though you might not even associate your gutters with the basement, a faulty gutter can lead to high moisture levels. It might be forcing water to move along the basement walls, leading to mold, mildew, and, yes, humidity. Poor exterior grading might not help the situation either. If water drains toward the foundation, it may seep into the basement.

Humid Basements in the Summer

When we think of humidity, we often imagine the summer months. If your basement turns into a sauna in the summer, you’re not alone. Here’s why the problem worsens during the hottest time of year:

• High Temperatures—When warm outdoor air enters your cool basement, it releases moisture and increases humidity levels.
• High Outdoor Humidity—If your basement is humid in summer, it’s likely because it’s getting humid outside. Summer’s elevated humidity levels seep into your home through doors, windows, and ventilation systems.
• Air Conditioning—Contrary to what you might think, using your AC in the upper levels of your home can make your basement more humid. By cooling off the upstairs air, AC systems can push warmer, moisture-rich air downward, leading to a damp basement.

Do Basements Get Humid in the Winter?

Humidity in the summer is no surprise, but basements can still feel damp during the colder months. While it isn’t as noticeable, humidity can wreak havoc on your basement if left untreated. Winter humidity usually results from:

• Water Intrusion—Snowmelt or winter rain can raise the water table and force moisture through cracks and foundation walls.
• Indoor Activities—Running humidifiers or drying clothes indoors during winter can inadvertently add moisture to your basement.
• Cold Pipes—Condensation can form on cold water pipes, drip onto surfaces, and create pockets of moisture.

Potential Risks of a Humid Basement

Now that you know why basements get humid, it’s time to look at the consequences of excess humidity. If you are lucky, you might not see significant damage due to moisture in the air. But more likely, you’ll have to deal with at least one of these effects:

Mold Growth

Mold thrives in damp, dark environments, and basements are often the perfect breeding ground. When mold spores spread, they can trigger a range of health issues, such as respiratory problems, skin irritation, and inflammation (in extreme cases). If you’re worried about mold, look for black, green, and white patches on the walls, flooring, and ceilings. Musty odors are another major red flag that you need to call mold assessment professionals.

Structural Damage

Water and excessive moisture in a basement don’t just stay in one spot—they seep into the structure of your home. Over time, this can weaken important elements like your foundation. Regularly inspect your basement for cracks or pooling water. If you notice any, consult an expert to evaluate the scale of the damage. Waterproofing your basement is a smart preventive step to avoid all the following:

• Cracked walls and floors
• A weakened foundation
• Rusted metal components
• Costly foundation repairs

Pest Infestations

Pest infestations are another big risk of allowing humidity to fester in your basements. Insects like termites and cockroaches love the damp environment, and even rodents are attracted to moisture. Once they’ve set up shop, pests can multiply quickly and expand to other areas of your home. To combat pest infestations, immediately seal gaps, vents, and foundation cracks to limit points of entry. Address humidity with a dehumidifier and perform regular pest inspections for peace of mind.

Damage to Stored Items

For many homeowners, the basement doubles as storage. Cardboard boxes, holiday decorations, memorabilia, and extra furniture are often kept there. Unfortunately, these items can be particularly vulnerable to excess moisture. This damage isn’t just inconvenient—it can destroy items with sentimental or financial value. Look for these signs that your items are at risk:

• Warped Furniture—Wooden items swell and bend in high-humidity conditions.
• Cardboard Deterioration—Boxes exposed to high humidity may start to break down and lose their shape. Eventually, moisture damage can reach the contents of these boxes.
• Mildew Growth—Fabrics like clothes, bedding, or furniture cushions may develop mildew. If you notice musty smells, you’re probably dealing with mildew growth.

Higher Energy Costs

If your basement is damp, your HVAC system is probably working harder than it needs to. Why? Humid air takes more energy to cool. While you might not be worried about a few dollars each month, even small increases in energy usage can add up significantly over a year. In addition to asking for help from our waterproofing professionals, you can use a dehumidifier to remove excess moisture.

Reduced Property Value

Ignoring a humid basement can have a major impact on your property value. When potential buyers tour your home, a damp or smelly basement is a huge red flag. Buyers might (rightfully) worry about mold, structural instability, and unusable storage spaces.

How to Fix a Humid Basement

Your approach to fixing a humid basement will differ depending on the amount of damage already done. If it’s simply humid and hasn’t started causing significant issues, a few days with a dehumidifier running may be enough. But if the moisture is widespread and stems from a deeper issue, you might need a more extensive fix. Here are our most used strategies for removing excess humidity in a basement:

Use Dehumidifiers

We’ve already mentioned dehumidifiers as a potential fix for too much moisture in the air, but these devices are truly a game changer. Place one in your basement and run it consistently, especially during summer months. Look for models with a built-in humidistat to monitor and maintain optimal levels.

Seal Cracks and Leaks

Unseen cracks and leaks in your basement walls are a common reason for too much humidity. Occasionally inspect your walls and floor for cracks or leaks, and should you find issues, use a waterproof sealant to patch them up. For major problems, call our team.

Improve Ventilation

Poor ventilation can make a humid basement even worse, and you may not notice an issue until it’s already causing problems. Try these methods for improving ventilation:

• Maintain Your Windows—If your basement has windows, ensure they are in good condition and open them regularly to allow fresh air to circulate. Consider adding window screens to keep insects out while maintaining airflow.
• Use Exhaust Fans—Install exhaust fans in areas prone to moisture, such as the bathroom or laundry room in the basement. These fans help remove excess humidity and promote air circulation.
• Utilize Portable Fans—Place portable fans strategically to promote air movement throughout the basement. Position them near windows or doors to draw in fresh air or create a cross breeze.
• Keep Basement Doors Open—Keep the doors to the basement open whenever possible to allow for better air circulation between the basement and the rest of the house.

Drain Water Away From the House

Check on your gutters—the problem might not be the basement itself! If your home’s gutters and downspouts are directing water to your foundation instead of away from it, you may need to call a professional for repair services.

Insulate Pipes

Cold pipes can lead to condensation and additional moisture in your basement. Wrap water pipes in foam insulation to prevent problems before they occur.

Waterproof the Basement

If you deal with chronic humidity issues, you likely need expert help. Our basement waterproofing technicians can look at your basement and recommend long-term solutions. We’ll discuss interior and exterior systems, as well as multi-step systems.

Preventing Worsened Humidity Problems

Those who’ve dealt with mold, mildew, and excess moisture know they never want to run into those issues again. Adopting these habits can help you avoid future humidity problems:

• Monitor Humidity Levels—Use a hygrometer to spot rising humidity levels before they get out of control. Ideally, basement humidity should stay between 30% and 50%.
• Maintain HVAC Systems—Ensure your home’s HVAC system is clean and in good working order. Properly functioning systems can do wonders for regulating humidity throughout your home.
• Regular Inspections—Make it a habit to inspect your basement for signs of dampness, pipe leaks, or potential cracks at least twice per year.
• Use Waterproof Storage Solutions—Store items in sealed, waterproof bins rather than cardboard boxes. This protects your belongings from unexpected moisture damage.

When to Call a Professional

If your basement humidity feels unmanageable despite your best efforts, it might be time to bring in an expert. Professional services, like basement waterproofing or HVAC inspections, ensure you’re protected against recurring issues in the long term. Reach out to the team at Everdry Waterproofing of Wisconsin if:

• You notice rapid mold growth or persistent musty smells.
• Your basement floods after heavy rains or during snowmelt.
• Cracks in your foundation are worsening over time.
• Waterproofing or dehumidifiers haven’t solved the problem.

Get in Touch With Everdry Waterproofing of Wisconsin

Dealing with a humid basement is no walk in the park. Although some quick remedies can help the situation, nothing beats having an expert weigh in. The team at Everdry Waterproofing of Wisconsin is proud to help homeowners in Milwaukee and the surrounding communities ensure their basements stay free of excess moisture and water damage. Contact us today to learn more about our services.