You step into your living room after a week of heavy rain, and there’s a damp, earthy smell that’s just… off. Maybe you’ve noticed something else: a soft spot on the floor near the back door or the persistent sound of water dripping beneath your home. These are red flags of moisture under the house, and can be a mold-breeding, wood-rotting, pest-inviting disaster waiting to happen. Thankfully, Lee Company has been protecting homes like yours since 1944!

In this blog, our home moisture control specialists will show you how to spot the signs, fix the issues, and keep your crawl space dry.

6 Signs of Crawl Space Moisture

Crawl space moisture doesn’t show up overnight. It sneaks in slowly over time, causing issues that homeowners often miss until the damage is done. The earlier you catch it, the better you can protect your home and wallet. Why wait for a repair bill that costs more than a family vacation when you can stop the problem? Here’s what to look for:

Musty Odors

Have you ever walked into a room and noticed a damp, unpleasant smell that lingers no matter how much you clean? That’s usually moisture under the house. It only takes 24–48 hours for mold to grow when moisture levels spike, especially after a season of our Southern thunderstorms followed by warmer weather. Don’t ignore these odors — they’re a subtle but early sign of moisture issues.

Visible Mold or Mildew

Grab a flashlight and peek under your house. Look closely at your crawl space walls, wooden beams, or insulation. See anything greenish-black or white and powdery? That’s likely mold or mildew, each with its own nasty consequences. Mold can spread fast, while mildew may just sit and stain — but both mean one thing: there’s moisture in the crawl space under your house, and it’s time to address it.

Damp Soil or Pooled Water

While inspecting the crawl space, check the ground for any signs of moisture. Is there damp soil or standing water? This could point to drainage issues, like clogged gutters or improper grading around your foundation. Pooled water doesn’t just sit there. It seeps, spreads, and leads to countless other issues (which we’ll get to later).

Condensation on Ductwork or Pipes

If the ductwork or pipes in your crawlspace are sweating like an ice-cold drink on a muggy Tennessee afternoon, you’ve got a humidity problem. This condensation adds moisture under the house, making it harder for your Heating, Ventilation, and Air Conditioning (HVAC) system to keep up. And if that excess moisture isn’t dealt with soon, it can set off a chain reaction of problems in your crawlspace.

Damp or Warped Wood and Flooring

Have you noticed your hardwood floors starting to flex? Are there beams in the crawl space that feel spongy or look darker? Do certain areas of your floors feel uneven, or are they visibly buckling? That’s wood rot in action, breaking down the very structure of your home. If the wood feels damp or spongy, don’t wait to address it. This isn’t just a cosmetic issue. It’s evidence that moisture under your house is already causing damage.

Pest Activity

Spiders in the corners, ants along the baseboards, or worse — termites chewing through your wood? These pests crawl spaces, especially when they’re damp. Spotting pest activity is a double warning: you’ve got moisture, and they’ve found it first.

Spotting the signs of crawl space moisture is just the first step. Ignoring these red flags can lead to costly consequences. Next, we’ll explore what happens when moisture problems are left untreated and why addressing them is so important.

Biggest Risks of Ignoring Crawl Space Moisture

The longer moisture under the house lingers, the greater the potential for significant crawl space problems that hit your home and wallet hard. And these risks don’t just stop at your crawl space. They creep into your air quality, your energy bills, and even your home’s structural safety. Here’s what can happen:

Health Risks

As we’ve mentioned, crawl space moisture creates an optimal breeding ground for mold, which can release spores into the air circulating through your home. According to the Environmental Protection Agency (EPA), mold exposure can lead to:

• Nasal stuffiness
• Throat irritation
• Coughing
• Wheezing
• Eye or skin irritation

For people with asthma or mold allergies, the risks are even higher. Mold exposure triggers asthma attacks, creating a serious concern for families with children or those with respiratory sensitivities. Is it worth letting crawl space moisture put your family’s health on the line?

Structural Risks

Crawl space moisture doesn’t stop at wood rot. It can compromise your entire foundation. Over time, excessive moisture can:

• Erode concrete
• Weaken floor joists and beams
• Shift foundation supports
• Cause cracks in walls and ceilings

In Tennessee, foundation repair costs can set you back $10,000 or more for major structural overhauls, such as replacing damaged beams or stabilizing shifting supports. The national average is around $4,500.

Ignoring crawl space moisture can turn a manageable issue into a financial nightmare. Acting quickly prevents a domino effect of damage and stops your repair budget from spiraling.

Energy Efficiency Problems

When crawl space moisture seeps into your home’s insulation, it lessens its ability to regulate temperature effectively. Wet insulation becomes compressed, losing the air pockets that trap heat during winter and keep it out in summer. This forces your HVAC system to work overtime to maintain a comfortable temperature, especially in Tennessee’s sweltering summers and humid conditions.

The result is higher energy bills and unnecessary damage to your heating and cooling systems — a double hit to your wallet. Addressing crawl space moisture helps you save energy and reduce long-term costs.

Pest Infestations

Moisture under the house creates the perfect conditions for termites to invade and feed on your home’s wooden structure. Since termites are most active in warm, humid climates like the Southeast, homeowners in Tennessee and surrounding states face an even higher risk of damage.

Other pests, like ants, cockroaches, and rodents, are also drawn to damp crawl spaces, seeking shelter and water. These unwelcome guests can quickly multiply and create additional problems for your home and health.

Main Causes of Crawl Space Moisture

If you notice issues like musty smells, wood rot, or pest activity, it’s not enough to treat the symptoms—you need to address the cause. Crawl space moisture often stems from multiple factors working together to create the perfect storm. Understanding these causes is the first step toward fixing the problem and preventing it from returning.

Poor Drainage Around the Foundation

When rainwater isn’t directed away from your home, it pools around the foundation, seeping into the crawl space. Improper grading, clogged gutters, or short downspouts can worsen the problem. Over time, this poor drainage leads to standing water under your home (a major contributor to moisture buildup).

Plumbing Leaks

Small leaks in pipes running through or above your crawl space can add up to significant moisture over time. The EPA estimates that 10% of homes have leaks, wasting an estimated 90 gallons of water per day. That excess water doesn’t just disappear. It collects in your crawl space, leading to mold and rot.

High Humidity Levels in the Region

In the Southeast, high humidity is a way of life, especially during the summer. This humid air enters your crawl space and condenses on cool surfaces, increasing moisture levels. Tennessee’s sweltering summers make this a persistent problem for many homeowners.

Insufficient Ventilation

A lack of airflow in your crawl space traps moisture, allowing it to accumulate. The damp air has nowhere to go without proper ventilation, leading to ongoing crawl space moisture problems. This is a common issue in older homes or those with improperly sealed crawl spaces.

Flooding or Heavy Rainfall

Heavy rainfall or localized flooding can overwhelm your crawl space, especially if drainage systems aren’t up to par. In areas prone to frequent storms, like Tennessee and our neighboring states, this is a recurring challenge that homeowners can’t afford to ignore.

Fixing crawl space moisture starts with identifying its root causes. Now that you know them, we’ll explore how to get rid of moisture under the house and protect your crawl space.

How to Get Rid of Moisture Under Your House

If you’ve spotted signs of crawl space moisture, the good news is that there are solutions. Below is a step-by-step action plan to dry out and protect your crawl space for good. With it, you can protect your family’s health and safety, keep your repair budget under control, and maintain your home’s value.

1. Repair Plumbing Leaks

Addressing leaks should be the top priority since water from pipes can continuously add moisture under the house. Check for water stains, rust, or drips, and make repairs to stop the flow at the source.

2. Dry Wet Areas

Any standing water or water-damaged items in the crawl space should be dried within 48 hours to prevent mold growth. Use fans, dehumidifiers, or professional help if necessary.

3. Install a Sump Pump

If your crawl space has frequent water pooling, a sump pump removes water quickly, reducing the overall moisture level and preventing flooding.

4. Inspect and Seal Cracks

Walk the perimeter of your crawl space and look for any gaps or cracks in the walls or foundation. Use a quality sealant to close them and keep water from sneaking in.

5. Improve Ventilation

Proper airflow helps prevent trapped moisture from building up again. Make sure all crawl space vents are open and unobstructed. If airflow is still limited, consider installing vent fans to help move the air.

6. Use a Dehumidifier

Once airflow is improved, a crawl space dehumidifier helps keep moisture levels within the EPA-recommended range of 30–60%. Choose one rated for your space and keep it running consistently, especially during humid Southeast summers.

7. Reduce Indoor Humidity Levels

Address sources of indoor humidity by venting bathrooms, kitchens, and dryers to the outside. This helps keep moisture from entering the crawl space in the first place.

8. Encapsulation

Crawl space encapsulation is the ultimate fix for long-term moisture control. A professional installs a heavy-duty vapor barrier to seal out water completely. While it’s an investment, it can save you thousands in future repairs.

By following these steps, you’ll tackle the moisture under your house and protect it from long-term damage. In the next section, we’ll cover how to prevent these problems from coming back.

How to Prevent Crawl Space Moisture in the Future

Preventing crawl space moisture is all about staying one step ahead. Regular crawl space maintenance and a few long-term investments can save you from costly repairs and protect your home’s integrity for years to come.

Seasonal Crawl Space Maintenance

• Check your gutters and downspouts each season to keep them clear and to direct water away from your foundation.
• Inspect crawl space vents to make sure they’re unobstructed and functioning properly.
• After heavy rain or storms, check your crawl space for standing water or damp areas.

Long-Term Solutions

• Waterproofing: Install proper drainage systems and seal foundation cracks to keep water out.
• Encapsulation: This airtight solution blocks moisture and prevents pests, mold, and harmful gases like radon from entering your home. Encapsulation can also lengthen your HVAC system’s lifespan by keeping humidity levels stable, and many homeowners notice a significant reduction in energy bills.
• Ventilation and Dehumidifiers: Maintain airflow and keep humidity levels under control with vent fans or a crawl space dehumidifier.

The longer crawl space moisture lingers, the more damage it causes to your home, your wallet, and your peace of mind. Protecting your home starts with prevention.

Since 1944, Lee Company has been helping homeowners across the Southeast with trusted solutions like crawl space services, plumbing repairs, and more. Financing options and Home Maintenance Plans are available to make it even easier. Contact us today to keep moisture where it belongs — outside your home!