Solved! Why Is My House So Humid?

If you’re wondering, “Why is my house so humid?” there can be several reasons—with some easier to fix than others.

By Melissa Maynard de Kerch | Updated Apr 6, 2022 4:45 PM

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Why Is My House So Humid


Q: My family recently relocated to a new home, and it feels incredibly muggy indoors. Our air conditioner seems to be working just fine, so why is my house so humid?

A: Figuring out why your house is so humid can take some troubleshooting, but it may prevent many issues in the future. But what is high humidity? According to Energy Star, the ideal indoor relative humidity should be between 30 and 50 percent–anything higher than 50 percent is considered high. High humidity levels and excessive moisture can cause discomfort and health issues, and it can even wreak havoc on a home. Excess humidity can cause condensation on windows, toilet tanks, and pipes. If you’re wondering what causes condensation, it happens when warm, moist air comes in contact with cool surfaces, and the vapor in the air turns into liquid water. Traces of moisture can spread to ceilings and walls, causing discoloration and mold growth. Peeling paint and creaking or buckling floorboards can also be a sign of excessive moisture.

Ultimately, high humidity levels have many different causes: climate, daily activities, and poor ventilation are just a few of the culprits. Read on to see if any of these issues may be present in your home.

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The climate affects the humidity level in your home.

Why Is My House So Humid The Climate Affects the Humidity


Climate can contribute to high humidity in a house. If it’s exceptionally humid outside, chances are it’s going to be muggy inside a home. The changing seasons and temperature can be significant factors for rising indoor humidity levels and the main culprit for an uncomfortable environment.

Everyday activities like cooking, washing, and showering can contribute to humidity levels.

Humidity levels can be affected by simple activities you do every day. These tasks can naturally add more moisture to the air. Cooking and running the dishwasher can add more water vapor to the air in the kitchen. Long, hot showers add a lot of moisture to the bathroom. Keeping areas ventilated by opening a window or installing an exhaust fan can lower humidity levels. A professional can direct certain appliances, such as clothes dryers and stoves, to vent outside of the home.

Leaks coming through cracks in the plumbing system may be the culprit.

An interior plumbing leak from a bathroom or kitchen sink can cause increased moisture in the air. It’s important to check pipes often for cracks and corrosion; finding a leak in the early stages could help prevent water damage, musty smells, and potential mold growth. While some leaks can be easy to spot, others are not. Look for wall discoloration, bubbling paint or wallpaper, a dripping sound, or a musty smell.

Why Is My House So Humid Moisture from Soil Under a House


Moisture from soil under your home may be penetrating the house.

Humidity can come up through the soil underneath the foundation of your home. This is called rising damp, and ineffective grading can be a significant factor since groundwater and rain can accumulate in a home’s foundation. Basements can be humid since they’re often poorly insulated and don’t have windows, and this can compound any issues.

If you live in a climate with excessive rain, ensuring that gutters and downspouts work correctly and rainwater is directed away from the house can keep moisture out. Professionally installed awnings placed above windows and doors are an excellent way to keep water out as well.

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A poor ventilation system may be to blame.

Adequate ventilation can help control a home’s humidity level, impacting health and a home’s structural integrity. If there are high humidity levels in your home, poor ventilation can be to blame. If you suspect that this is the reason behind your discomfort or even health issues (high humidity indoors can lead to respiratory problems), a first step is to open windows and keep them open for extended periods for humidity control, particularly in high moisture areas such as bathrooms and kitchens. Also, consider having a ventilation system professionally installed.

Your AC unit may be too large.

Bigger isn’t always better: An oversize window or central AC unit may be the reason for excessive moisture in a home. The evaporator coil found inside the AC unit acts as a dehumidifier and pulls humidity from the air as it runs. However, if the unit is too large, it may cool a room or home too quickly, running for only 10 to 15 minutes on a hot day before it abruptly shuts down. A longer runtime is needed to dehumidify a home correctly.

It might be time to call a pro
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