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Relative Humidity

When trying to figure out ways to make the indoors dry and comfortable, relative humidity is an important factor to consider.

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Whether you learned about relative humidity in junior high school or heard your home inspector talk about it, you can’t ignore its impact on your home. When it’s high, you are likely to experience dampness, mold growth, and a range of respiratory problems. Let’s not forget the ensuing structural damage as well. And when the relative humidity drops, the air will feel dry and you may experience eye and throat irritation. 

You can learn more about relative humidity, how it’s measured, its side effects, and how to maintain ideal levels of relative humidity in your home in the sections below. 

insulation to control humidity

What Is Relative Humidity? 

Simply put, relative humidity (RH) is a term that describes the amount of water vapor in the air in terms of percentage point. In other words, it’s the amount of water vapor that the air can hold at a particular temperature. 

For example, a 100% relative humidity means that the air is saturated and cannot hold any more water. However, air cannot hold onto water vapor for long, especially as the overall temperature in your home changes. So, when the air in your home cools, the water vapor will condense into water droplets, making the walls and floor damp.   

High relative humidity of above 50% can make the indoors uncomfortable. The excess moisture can encourage mold and mildew growth, which can worsen your asthma or allergies. That’s not to mention that higher moisture levels can instigate wood rot. 

Sources of Moisture 

There are several ways moisture can enter and stay in your house. Rooms where water is used more frequently, such as the kitchen and bathroom, tend to be more humid than other areas of your home. Humidity can also occur in your home due to: 

  • Roof leaks 
  • Rainwater 
  • Houseplants 
  • Leaking sinks, toilets, and pipes 
  • Clothes dryers that are used extensively 
  • Poor ventilation 

What Is the Ideal Relative Humidity? 

According to the Environmental Protection Agency (EPA), the ideal range of relative humidity for a home is between 30% and 50%. Anything higher or lower than that is likely to cause problems. This, of course, depends on the climate you live in as well as your personal preference.  

Effects of High Relative Humidity in Your Home 

The air’s ability to hold moisture changes with rising and falling temperatures. Generally, when the air is warmer, it can hold more water, and when it’s cooler, it tends to dry out.  

Higher relative humidity can lower the quality of indoor air, which can harm your physical health and the health of your home as well. Keep an eye out for these issues: 

  • Mold and mildew growth 
  • Peeling wallpaper or bubbling paint 
  • Musty smells throughout your home 
  • Warped wooden floors and furniture 
  • Condensation on windows 
  • Sticking window and door frames 
  • Water stains on walls or ceilings 
  • Malfunctioning electronic equipment. 

Effects of Low Relative Humidity 

Just as excessive humidity levels can be damaging to your home, so can low humidity levels. However, the effects of low humidity are milder and this can make it hard to notice there is a problem. Common ones include: 

  • Shrinking wood furniture, food, and window frames 
  • Peeling wallpaper 
  • Hardwood floor separation and warping 
  • Gaps between the walls and ceiling 

Ways to Attain Optimal Relative Humidity 

Left unchecked, relative humidity levels in your home can swing from high to low quickly. So, you need to keep it at an optimal level, between 30% and 50%. One way of doing this is installing both a dehumidifier and a humidifier. A dehumidifier dries out the air by removing excess moisture from the atmosphere. This helps eliminate damp, musty odors in your basement or crawl space and makes the environment less hospitable for allergens like dust, mold, and mildew. If the air dries out completely, you can moisten it a bit using a humidifier. 

Another way of controlling indoor humidity levels is installing a sump pump in your basement or crawl space. What this does is prevent rainwater from flooding the space and turning it into a waterpark. While you’re at it, don’t forget to fix those annoying plumbing leaks around your home as they can drive up indoor humidity levels. 

We also recommend sealing out any open crawl vents and covering any exposed dirt or concrete crawl space floor with a 20-mil vapor barrier. This will help hold back moisture-laden outside air. 

For all your basement and crawl space humidity issues, contact the Tar Heel Basement Systems experts to receive a free inspection and repair quote today.

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