What Is Crawlspace Encapsulation?
Encapsulation is the process of sealing your crawlspace to keep out moisture. The goal isn’t to make the area airtight, but to block as many entry points for moisture as possible. Water vapor can seep through brick, concrete, and even rise up from the dirt. Encapsulation creates a barrier that keeps moisture from entering, helping protect the structure of your home.
Why Encapsulate?
The main goal is to take control of the crawlspace air so a dehumidifier can regulate humidity effectively. It’s not about keeping air out, it’s about managing the air inside.
When relative humidity stays above 60%, conditions become perfect for mold, fungus, dust mites, and wood decay. These problems not only damage your home’s structure but also affect your indoor air quality and your family’s health. Encapsulation helps you keep humidity low and these issues out.
How Is It Done?
Here’s a simple breakdown of the process:
- A thick plastic vapor barrier is installed on the crawlspace floor.
- The plastic is wrapped up walls and around piers, with seams sealed together.
- The top edge of the plastic is secured to the wall using glue, tape, or spray foam.
- All vent openings are sealed to keep humid outside air from entering.
- A dehumidifier is installed to control humidity.
- The dehumidifier drains via a gravity line or a condensation pump.
- If the crawlspace has wood framing, the plastic is held about 6 inches below to keep termite activity visible.
Insert DURING photo here (showing plastic being laid or vents being sealed)
What’s the Benefit?
A dry crawlspace means a drier, healthier home. Moisture naturally moves from high to low, so if your crawlspace is damp, that moisture can move into the living space above. This leads to floor warping, trim movement, and poor air quality.
Older homes had hardwood floors that let moisture escape, but today’s homes use materials that trap it. Without encapsulation, moisture gets stuck and leads to mold, mildew, and damaged insulation or wood framing. Encapsulation allows an old design to work with new building materials—keeping your home protected and your air clean.
Can Anything Else Help?
In theory, yes, but it’s not always reliable. Crawlspaces were originally designed to stay dry through natural ventilation. Outside air was supposed to flow in through vents to dry the space.
But when those vents are blocked by porches, landscaping, or nearby buildings, air stops moving and moisture builds up. Plus, in the Southeastern U.S., humidity often stays above 60% for weeks at a time, so even the outdoor air is too damp to dry anything. That’s why ventilation alone usually doesn’t work in this region.
What About Building Code?
Yes, the International Residential Code (IRC) regulates crawlspaces. It requires a certain number of vents per linear foot, a minimum crawlspace height, and vent placement. However, it does not prevent vents from being blocked by landscaping, porches, or driveways.
If you encapsulate a crawlspace, the code also requires that the air inside be either mechanically ventilated or conditioned (e.g., with a dehumidifier) to meet compliance standards.
Should You Do It?
Some crawlspaces stay dry on their own and don’t need much help. Others are in such poor condition—due to moisture or rot—that encapsulation is the only way to stop things from getting worse.
For many homeowners, encapsulation is a worthwhile investment. It improves comfort, air quality, and long-term protection. While it may not be the most urgent need for every home, it never hurts—and often solves problems you didn’t know were connected.
If you’re not sure, we’re here to help. We’ll give you a free inspection and honest feedback so you can make an informed decision for your home and family.
