Moisture can wreak havoc on a home’s structure and indoor air quality. If excess moisture builds up beneath your living space, you could experience warped hardwood floors, musty odors, and mold growth. Learn the signs of excessive humidity and long-term solutions to address and prevent crawl space moisture.
Signs of Moisture Problems in Your Crawl Space
Knowing what signs to look for helps you catch moisture problems early and take action before significant damage occurs.
Warping or Cupping Hardwood Floors
Damage to hardwood flooring is one of the most noticeable signs of crawl space moisture. Excessive humidity seeping up from the crawl space can cause wood floors to warp, cup, or buckle. It affects the appearance of your floors and can also lead to costly repairs if left unaddressed.
Musty Odors
A persistent, musty odor is another sign of a moisture problem. The odor may come from stagnant standing water, mold, mildew, or groundwater entering your crawl space through cracks in the foundation.
Visible Mold or Mildew
Mold and mildew thrive in damp environments, and small patches can quickly spread and pose health risks to your family. It’s especially a concern if anyone in your family has asthma. Grab a flashlight, put on your oldest clothes, and head into the basement or under the crawl space to look for signs of mold growth on the subfloor or floor joists.
Pest Infestations
Termites, rodents, and other critters will seek environments with high moisture levels. An increase in pest activity might indicate that your crawl space has a moisture problem.
Identifying the Source of Moisture
You can’t solve a moisture problem unless you know where the water is coming from. If you suspect moisture is getting into your home, there are several common sources you should investigate.
Poor Drainage Around the Foundation
Proper grading or landscaping directs water away from your home’s foundation. Any dirt or ground near your house should have a slight slope away. Otherwise, the ground’s angle sends water toward your home, which can lead to water seeping into the crawl space, especially during heavy rains.
Plumbing Leaks
Over time, a small leak in a pipe or fixture can contribute significant moisture to your crawl space. Regular inspections help catch these issues early. Your water bill increasing could indicate a leak somewhere in your system.
High Humidity Levels
In some cases, the problem may not be liquid water from rain or a leak but high humidity in the air. If you live in a naturally humid climate, look out for moisture when it’s particularly humid outside.
Groundwater Intrusion
Groundwater can get into the crawl space after a heavy rainfall or storm. You can identify groundwater intrusion by persistent dampness or standing water in your basement or crawl space.
6 Steps To Solve Moisture Problems
Once you’ve identified the signs and potential sources of moisture, take these steps to address and prevent crawl space moisture issues:
1. Conduct a Thorough Crawl Space Inspection
Perform a detailed inspection of your crawl space, or hire a professional to do it. Look for standing water, plumbing leaks, saturated soil, and signs of mold or mildew. The inspection results will guide you in your next steps to resolve the moisture problems.
2. Improve Exterior Drainage
Check that the ground around your foundation slopes away from the house at a rate of at least half an inch per foot. This simple step reduces the amount of water that enters your crawl space.
3. Install or Repair Gutters and Downspouts
Gutters and downspouts direct rainwater away from your home’s foundation, but when they’re clogged or broken, water can pool near your foundation. Clean your gutters regularly and check for broken or clogged downspouts or grates. Extend downspouts at least 5 feet away from the house.
4. Check and Maintain Your AC Drain Pipe
Air conditioning systems produce condensation. If not properly drained, this moisture can enter your home. Check your AC drain pipe for clogs. Install window AC units so they tilt down and away from the house, or water can pool on your windowsill and drip into your walls.
5. Treat Existing Mold and Mildew
Treat any mold or mildew discovered during your inspection promptly. Products like Wet and Forget can be effective for treating affected areas, or consider using Drylok paint to lock out moisture. Consult a professional mold remediation service if you have extensive mold issues.
6. Install a Vapor Barrier or Paint
Installing a vapor barrier or using Drylok paint in your crawl space can prevent moisture issues. To prepare your crawl space for a vapor barrier, remove debris, old insulation, or stored items. Any paper or textiles that have gotten wet or grown mold should probably be thrown out. Fill in any holes or depressions in the soil to create a level surface.
Next, cover the entire crawl space floor with thick, black plastic sheeting (6 mils or higher). Overlap the vapor barrier at the seams by at least a foot and run it up the sides of the foundation walls.
Advanced Moisture Control Techniques
If basic moisture control measures aren’t enough, invest in these advanced techniques:
Install a Dehumidifier
Installing a dehumidifier in a crawl space or basement removes moisture from the air. Choose a model specifically designed for the space and purchase the right size for your square footage.
Seal Crawl Space Vents
While it may seem counterintuitive, in many climates, sealing crawl space vents can actually help control moisture. It prevents humid outside air from entering the crawl space and condensing on cooler surfaces.
Improve Crawl Space Insulation
Consider insulating the walls and possibly the ceiling of your crawl space. Proper insulation maintains a consistent temperature in your crawl space, reducing the likelihood of condensation.
Install a Sump Pump
If you have persistent water intrusion, particularly if it creates pools or standing water, installing a sump pump can help keep your home dry. Sump pumps collect and pump out water that accumulates in the crawl space, preventing it from causing moisture problems.
Consider Crawl Space Encapsulation
For homes with persistent moisture issues and all else has failed, crawl space encapsulation might be the only long-term solution. This process completely seals the crawl space from outside air and moisture and often includes installing a dehumidifier to control humidity levels.
Maintaining a Dry Crawl Space
Once you’ve addressed existing moisture issues, maintain a dry environment going forward. Regular inspections, prompt repairs of any water leaks, and monitoring of humidity levels can prevent future problems.
Schedule Regular Inspections
Put reminders in your calendar for crawl space inspections, especially before and after the rainy season. Look for signs of water intrusion, mold growth, or damage to moisture control systems. Also, check that your dehumidifier is still working if you have one.
Monitor Humidity Levels
A hygrometer is an instrument that monitors humidity levels. Installing one in your crawl spaces allows you to track and keep the relative humidity below 60% to prevent mold growth and other moisture-related issues.
Address Issues Promptly
Address any signs of moisture returning to your crawl space immediately. Quick action prevents small problems from becoming major issues, and it’s usually cheaper to fix a minor problem than a big one.
Maintain Your Gutters and Downspouts
Regularly clean and inspect your gutters and downspouts to keep them functioning properly. Consider leaf guards or grates to prevent gutters from getting clogged.
Final Thoughts About Solving Moisture Problems Under Your Home
While many moisture control measures can be do-it-yourself projects, some situations may require professional assistance. Don’t hesitate to consult a specialist if you’re dealing with severe moisture issues or you’re unsure about the best approach.