If the Crawl Smells Musty or Holds Water
A musty smell, visible mold, or standing water in your crawl space means moisture is getting in—and staying. Encapsulation can solve the long-term problem, but you need to find and fix the water source first.
The Right Sequence:
- Identify where the water is coming from
- Fix drainage, downspouts, or plumbing leaks
- Remove standing water if present
- Address existing mold if needed
- Then install encapsulation to prevent future moisture
Common Moisture Sources in Des Moines Crawl Spaces
Ground Moisture
Iowa's 36.55 inches of annual precipitation means groundwater can wick up through a dirt floor. Even without pooling, this constant evaporation raises relative humidity and creates that damp, earthy smell.
Poor Drainage
If your gutters overflow, downspouts discharge too close to the foundation, or the yard slopes toward the house, water pools around the crawl space and seeps through foundation walls or vents.
Foundation Cracks
Freeze-thaw cycles (Des Moines January lows average 13.8°F) can crack concrete over time. Water follows these cracks into the crawl.
Open Vents
Vented crawl spaces let in outdoor humidity during summer. When that warm, humid air hits cooler surfaces inside, it condenses—adding moisture instead of removing it.
Plumbing Leaks
A slow drip from a pipe or water heater can go unnoticed for months, pooling below.
What About Mold?
Mold grows when relative humidity stays above 60% (per EPA guidance) and organic materials like wood or insulation provide a food source. If you see visible mold or suspect it:
- Have a contractor assess the extent
- Remove affected materials if needed (soaked insulation, contaminated wood that can be replaced)
- Clean hard surfaces with appropriate methods
- Address the moisture source before sealing the space
Encapsulation prevents future mold growth by keeping humidity low, but it does not remove existing mold. That step comes first.
We Do Not Make Medical Claims
Mold exposure affects people differently. We cannot claim encapsulation will cure health symptoms. If you have health concerns, consult a doctor. Our role is to connect you with contractors who can control moisture and prevent mold growth.
Will DampRid or a Deodorizer Fix It?
No. Products like DampRid or odor-absorbing bombs treat symptoms, not causes. They can pull some moisture from the air temporarily, but they won't stop water from entering or fix the underlying humidity problem. You need to address the source: seal the ground with a vapor barrier, fix drainage, and control the environment with a proper dehumidifier.
Standing Water: What to Do First
If you have standing water in your crawl space right now:
- Check for active plumbing leaks and shut off water if needed
- Pump out or wet-vac the standing water
- Identify where the water came from (surface runoff, groundwater, broken pipe)
- Have a contractor evaluate whether you need a sump pump, perimeter drain, or exterior grading fixes
- Then proceed with encapsulation once the space is dry and drainage is corrected
Encapsulating over standing water just traps the problem. The liner will float or deteriorate, and you'll still have moisture issues.
EPA Guidance on Relative Humidity
The EPA recommends keeping indoor relative humidity below 60% to inhibit mold growth. A properly encapsulated crawl space with a working dehumidifier can maintain RH in the 40–50% range, making it inhospitable for mold.
Get Help from Local Contractors
Connect with licensed Des Moines-area contractors who can assess your moisture source, recommend drainage solutions, and provide encapsulation quotes.