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How to Protect Your Crawl Space from Relative Humidity

hygrometer showing humidity level

Humidity can do more than just frizz your hair—it can wreak havoc on your home and health. High humidity levels lead to mold growth, structural damage, and may even cause respiratory issues.

Low humidity isn’t great either, causing dry skin, increased flu risk, and cracked walls. Let’s dive into why managing the relative humidity in your crawl space is crucial for a safe and comfortable home.

Relative Humidity Explained

Relative humidity will tell you how much moisture is currently in the air compared to what the air can hold at that temperature. Some of the factors that can affect relative humidity are air saturation, temperature, and the dew point.

Due to these changing factors, relative humidity is always changing as well. Relative humidity is expressed in percentages. The higher the percentage, the more humid the air is. 

What Is a Normal Relative Humidity Level? 

According to The Environmental Protection Agency (EPA), the humidity level in your home “should be kept below 60 percent — ideally between 30 percent and 50 percent”. Levels below 30% can cause dry skin and respiratory irritation, while levels above 50% can lead to mold growth and structural damage. Use dehumidifiers in humid months and humidifiers during dry seasons to keep your home comfortable and safe year-round.

How to Measure Relative Humidity

crawl space humidity measurement

Measuring the humidity level in your home is simple with a hygrometer. This handy device gives you a precise reading of the moisture in the air. Just place the hygrometer in a central location in your home, and it will display the current humidity level.

Keeping an eye on these levels is crucial because when relative humidity is too high or too low, it can lead to health issues and damage your home. If you need assistance, our team provides free inspections and can measure the relative humidity in your home as part of the process.

Effects of High Humidity Levels 

If the humidity levels in your home are too high, here are some of the problems that may pop up: 

Rotting wood and rusty metal support post in a crawl space,
  • Lowers indoor air quality: Various fungi, bacteria, and viruses thrive in humid places and can easily spread throughout your home. They can contaminate the air you breathe and cause a range of health issues. 
  • Aggravates health issues: If any of your family members have respiratory problems, such as asthma, or have allergies, their condition will worsen if the humidity levels rise. 
  • Damages your structure: Fungi that attack the wood and cause it to rot are attracted to humid places. Wood rot can compromise the stability of your home and lead to a musty smell or termite infestations. High humidity can even damage your floors, art pieces, furniture, and electronic devices. 
  • Increases your energy bills: Since your home will become damp due to high levels of humidity, you will need to run your air conditioner more often than you would. This will impact your energy bills and cause you to spend more money. 

Effects of Low Humidity Levels on Your Home 

If, on the other hand, the humidity in your home drops below the desired level, this can also cause a myriad of problems. For example, air that is too dry can irritate the mucous membrane and make asthma and allergy symptoms flare up.

Also, flu viruses spread more quickly in these conditions, so there is a higher risk of sinus infections. At the same time, you may struggle with chapped lips and dry skin.

Low humidity can damage your home in several ways, including cracking walls and ceilings, separating wood floors, and shrinking door and window frames. 

How to Lower Relative Humidity

If your crawl space is unprotected, moisture can easily enter your home, increasing humidity levels and causing various problems. To prevent this, encapsulate your crawl space with the help of local contractors like AFS. Here’s a comprehensive guide to the tools and methods used in crawl space encapsulation:

Vapor Barrier

Fully encapsulated crawl space.

A vapor barrier covers the walls and dirt floor of your crawl space, preventing outside air from seeping in. This protective layer reduces moisture and helps maintain a stable indoor environment.

Install a Dehumidifier

Dehumidifier in a crawl space.

A dehumidifier is one of the best ways to control humidity levels in your crawl space. It removes excess moisture from the air, making the environment less inviting for mold, fungi, and pests.

Sump Pump

Sump pump in a crawl space.

A sump pump is crucial for preventing water accumulation in your crawl space. It collects and removes water that enters, keeping the area dry and reducing the risk of mold and structural damage.

Foam Board Insulation

Man placing insulation on crawl space wall.

Foam board insulation helps maintain temperature and humidity levels in your crawl space. It provides a barrier against moisture and improves energy efficiency by reducing heat transfer.

Crawl Space Drainage

Freshly placed crawl space drainage line.

Proper drainage is vital for keeping your crawl space dry. Crawl space drainage systems direct water away from your home, preventing it from accumulating and causing damage.

Drainage Matting

man crawling on drainage matting in a crawl space.

Drainage matting helps control water flow beneath your vapor barrier. It creates channels for water to move towards the sump pump or drainage system, ensuring your crawl space stays dry.

Crawl Space Door Sealing

Man installing a crawl space door.

Getting a crawl space door with better sealing prevents moisture and pests from entering. A properly sealed door enhances the effectiveness of your encapsulation efforts and contributes to a healthier home environment.

Get Professional Crawl Space Help With AFS

AFS crewman inspecting a crawl space door.

For help controlling humidity in your home, contact AFS Foundation & Waterproofing Specialists. We serve homeowners in Alabama, Mississippi, Tennessee, Florida, and Georgia.

Our experts can recommend the best solutions for your home. Contact us today to schedule a free inspection and keep your home comfortable and healthy by managing indoor humidity.

Relative Humidity FAQs

Relative humidity is the amount of moisture in the air compared to its maximum capacity. Normal humidity is the ideal moisture level for comfort, usually between 30% and 50%.

Yes, 70 percent humidity is high. Ideal indoor humidity is between 30% and 50%.

Upon installation, drainage matting immediately redirects water toward your drainage system or sump pump. While the rate of water diversion depends on volume, our matting is engineered for efficient drainage across diverse conditions. Learn more during a free inspection with AFS experts.

Related Resources

Ted Dryce

Ted Dryce

Content Writer

Ted is an SEO Content Writer who has been with Groundworks since 2021. He’s covered home repair topics ranging from crawl space encapsulation to regional soil conditions. When he’s not working, Ted is performing improv comedy and working on his own creative projects.

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