What You Can Learn from a Real Homeowner Inspection
If your crawl space smells musty, has fallen insulation, or shows signs of water stains on the foundation wall don’t panic. These are common warning signs of moisture problems, and with the right tools and knowledge, you can address them yourself.
In this post, we break down a real crawl space inspection from a Crawl Space Ninja branch in North Georgia. You’ll get the same insights our service teams provide—now adapted for DIYers who want to inspect, clean, and maintain their own crawl spaces.
What to Look For in a DIY Crawl Space Inspection
Whether you're experiencing high humidity, moldy smells, or just curious about what’s under your home, here are common signs to check:
Sagging or Fallen Insulation
Insulation can fall when it’s installed improperly or when it becomes saturated with moisture. A crawl space that stays humid will eventually compromise your insulation—even if it was brand new.
White Stains on Foundation Walls
This is called efflorescence—a powdery white substance that forms when water pushes through concrete or block. It’s a clear sign of moisture problems.
Mold on Wood Joists
Mold can look like small black dots, white film, or large dark stains. Any mold is a problem, no matter the type.
High Humidity
Use a hygrometer (available at most hardware stores) to measure relative humidity. Anything above 60% is a risk for fungal growth and wood rot.
Musty Smells Inside Your Home
If your house smells like earth or mildew, especially when the HVAC system runs, there’s a good chance your crawl space is contributing to it.
Should You Test for Mold?
As we explain in our videos, you don’t have to test to confirm you have mold. If it looks like mold, smells like mold, and is growing on your joists or walls it needs to be removed. Not just sprayed.
But if you want confirmation, we do offer a DIY surface mold test kit. It includes swabs you can send to a lab to identify mold types. Note: Crawl spaces are not considered living areas, so air samples are not generally recommended.
DIY Mold Remediation: How to Tackle It Yourself
Once you’ve confirmed moisture or mold, here’s how to handle it using methods inspired by the inspection walkthrough with James Derry and Michael Church:
Clean Out the Crawl Space
Remove debris, fallen insulation, and anything moldy or wet. Insulation can hold onto moisture and spores—get it out.
Dry the Area
Use a crawl space-rated dehumidifier to dry out the space for 7–14 days before performing any mold treatment.
Air Seal the Subfloor
Before you clean the wood, seal gaps in the subfloor with foam or caulk to prevent cleaning agents or soda dust from entering your living space.
Scrub Mold Off Wood
For a DIY, use a fogger and mold cleaner to remove surface mold from joists and framing. Sodium bicarbonate is highly effective and environmentally friendly.
Apply a Mold Sealant
Once cleaned and dried, apply a penetrating mold sealant—not just a paint-like encapsulant. The right sealant soaks into the wood and helps block moisture from being reabsorbed. Such as the Anabec x70 Moisture Barrier
Lay a Vapor Barrier
Cover the ground with a reinforced vapor barrier (like 12-mil or thicker) to stop ground moisture from re-entering the crawl space.
Add Ventilation if Needed
For sealed crawl spaces, consider installing a small ventilation fan to move air out. This helps reduce radon and soil gases and complies with EPA Indoor airPLUS recommendations.
How to Maintain Your Crawl Space (DIY Style)
While our service teams may offer maintenance, DIY homeowners can absolutely manage upkeep themselves. Here’s how:
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Change Dehumidifier Filters Every 6 Months
Dirty filters reduce airflow and force the machine to work harder, increasing the chance of failure. -
Clean the Condensate Pump and Drain Lines
Rubber tubing can clog or harden over time. Flush lines with water or a pump cleaner every few months to prevent overflow. -
Check for Mold or Moisture Quarterly
Look for new stains, fallen insulation, or increased humidity. Crawl spaces are “out of sight, out of mind”—don’t let that lead to hidden damage. -
Inspect Your Vapor Barrier
If you see puddling, tears, or mud, your barrier may need repairs or replacement. Make sure it’s fully covering the ground and properly sealed.
The Bottom Line
This project was handled by a Crawl Space Ninja branch, but as a DIYer, you can absolutely take on these same steps with the right tools and preparation.
Remember:
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You don’t have to live with mold or musty smells
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You don’t need to know what kind of mold it is—you just need to clean and seal it
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Crawl space moisture is manageable with the right plan
Want help choosing the right vapor barrier, mold cleaner, or dehumidifier for your project? Visit the Crawl Space Ninja DIY Store, where everything is selected for homeowners just like you.