Does your house feel like a sauna during the hot summer months? Are you wondering, “why is my house so humid”? This article will help you explore the causes of high humidity levels in U.S. homes, and ways to tackle the problem. 

And tackle you must. The high humidity level can be quite problematic. 

Not only does the heavy, moist air make your living uncomfortable, but it can also lead to mold growth, poor indoor air quality, and wood rot. And, serious health issues such as skin and respiratory problems.   

So, why is my house so humid, you’ll ask? There could be many causes for your home’s high humidity. Based on the specific problem, you could fix the issue and make your house feel comfortable as well as smell fresh all year round.

What are the symptoms of excessive humidity in your house?

signs of humid house

While we understand that you can’t keep measuring the humidity levels in your home with a humidity or dew meter, there are some important telltale signs that indicate that the humidity is too high inside your home. These could include clammy skin, visible moisture buildup, foggy windows, and a heavier atmosphere. Perhaps a musty odor, dust mites, or the smell of mold and mildew.

Here are some of the signs you can watch out for. 

  • Visible condensation on cooler surfaces such as windows, room mirrors, plumbing pipes, and in your basement area. If you spot any of these, check the surrounding area to see if the moisture spreads to the walls.
  • Wet stains on the ceiling, dark spots, discoloration on the walls, or crumbly stucco. 
  • Peeling paint or creaking floorboards.
  • Continuous headaches, shortness of breath, frequent allergy symptoms such as wheezing or chronic cough.
  • A distinct odor of mold and mildew.

If you experience any of the above symptoms, you should have your home thoroughly checked.

Read more: Condensation spots on walls

Why is my house so humid?

Several factors contribute to your home’s humidity. Apart from the obvious effects of the surrounding climate and temperature, you’ll also have to consider the house design, its construction and the building materials, the use of a vapor retarder, the home’s insulation, and how airtight the property is. 

Then, there are other factors such as an ineffective (too large or too small) air conditioner capacity or oversized windows that you must consider. Let’s explore all the reasons below.

The local climate 

Climate can directly affect the humidity in a house. For example, a house in Florida will have much higher average humidity than say one located in California.

It’s likely to be musty inside a residence if the outside air is unusually humid. The primary cause of an uncomfortable living atmosphere and a key contributor to growing indoor humidity levels are the changing seasons and temperature fluctuations. A good way to deal with this issue is to insulate your home well. 

Poor ventilation system

ventilation in house and humidity

A sound ventilation system and air circulation can help control a home’s humidity, structural integrity, and health. 

Also remember that everyday activities such as cooking, running the dishwasher, and long hot showers can affect humidity levels – naturally adding more moisture to the air. The solution to this problem is to keep moisture-prone areas such as bathrooms and kitchens well-ventilated by opening a window or installing an exhaust fan. You can hire a professional who will direct your home appliances, such as clothes dryers and stoves, to vent outside of the home.

Plumbing leaks

A leak in the plumbing system – either from a bathroom sink or a kitchen sink – can increase the moisture in the air. It’s important that you regularly check the plumbing pipes for any cracks, leaks, or corrosion.

If you spot wall discoloration, bubbling wallpaper, peeling paint, a dripping sound, or a musty smell – you have a leak.

Finding and dealing with a plumbing leak in the early stages could help you prevent serious water damage, musty smells, and potential mold growth.

Read more: Old house plumbing

Moisture from the soil beneath your home

The soil underneath your home’s foundation can penetrate inside your home as rising damp. The reason could be ineffective yard grading that allows groundwater or excessive rain to accumulate near your home’s foundation. Poorly insulated basements can make the issue worse.

To prevent this problem, ensure good yard grading and remember to clean your rain gutters and downspouts correctly and regularly. You may even consider installing awnings above your windows and doors to keep the water out.

Read more: How to remove old gutter sealant

Your HVAC system may be inappropriate

An oversize window or a too-large AC unit may be the reason for the excessive moisture inside your house. The evaporator coil inside an air conditioner acts as a dehumidifier and pulls humidity from the air. However, if the air conditioning system is too large, it may cool a room too quickly. It will not have sufficient runtime to dehumidify your home properly. Therefore, it’s always a good idea to consult an HVAC technician before installing a cooling or heating system in your home. The ultimate goal is to achieve the ideal humidity level inside your home for safe and healthy living.

Last thoughts

We’re sure you’ll not ask why is my house so humid, again. Now you know the culprits and the ways to reduce humidity in your home. Excessive humidity is not just uncomfortable, it can be detrimental to your health and home. In the worst-case scenario, excessive moisture can be suffocating or lead to breathing problems. Therefore. It’s important to maintain the ideal level of humidity indoors.

Why is my house so humid? Get answers here! was last modified: April 4th, 2023 by Ramona Sinha
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