Encapsulated vs Sealed Crawl Space: What’s the Difference?

A sealed crawl space has closed vents and plastic on the dirt. An encapsulated crawl space has closed vents, a reinforced barrier sealed across the floor and up the walls, insulated perimeter walls, and a dehumidifier. Contractors use the two terms loosely, and some sell a sealed crawl space under the encapsulation name. This guide shows you the difference, what each one costs you in performance, and which one holds up in North Georgia humidity.

What an Encapsulated Crawl Space Includes?

Crawl space encapsulation treats the crawl space as part of the house. Every surface touching soil or outside air gets covered and sealed, and the air inside is conditioned or dehumidified. Five things define it.

• Reinforced barrier, 12 to 20 mil, across the floor, up the foundation walls, around every pier, with seams overlapped and taped.
• Foundation vents sealed
• Insulation on the perimeter walls instead of between the floor joists
• A dehumidifier sized to the space, or a conditioned air supply
• Access door sealed and insulated.

For the benefits, costs, and when encapsulation is worth doing, read Is crawl space encapsulation worth it.

What a Sealed Crawl Space Includes

A sealed crawl space closes the foundation vents and lays plastic on the ground. That is the whole system. The plastic is often 6 mil, rarely runs up the walls, and is seldom taped at the seams. There is no dehumidifier. There is no wall insulation.

Key Elements of a Sealed Crawl Space

Closed foundation vents: Existing vents are sealed or closed to prevent outside air from entering.

Basic vapor barrier: A lighter-weight plastic sheet is laid on the ground, often without extending up the walls or being sealed at the seams.

Limited moisture control: Basic measures such as exterior drainage may help, but there is no complete humidity control system.

What Sealing Misses

Ground moisture still rises. Thin plastic with open seams lets vapor through. Georgia clay pushes water up through the dirt all summer.

Humidity has nowhere to go. Vents used to let some of it out. Closed vents with no dehumidifier trap it. A sealed crawl space in August often reads higher humidity than a vented one.

Condensation moves to the ductwork. Warm, damp air meets cold ducts and drips.

Wood stays wet. Joists sitting above 19 percent moisture content rot, sealed or not.

No energy benefit. Without wall insulation and dry air, the floor above stays cold in winter and damp in summer.

The failure pattern is predictable. The space is dry the first spring. By the second summer, it smells the same as before. The homeowner then pays for the encapsulation they were told they had.

Encapsulated vs Sealed Crawl Space: Key Differences

To better understand the difference between encapsulated and sealed crawl space systems, the comparison below shows what each system actually includes.

Which One Holds Up in Georgia

Sealing works in dry climates. In North Georgia, Tennessee, and the Carolinas, outdoor humidity runs 70 percent or higher for four months a year, and the clay soil stays wet weeks after rain. A sealed crawl space here has no way to remove the moisture it traps. Encapsulation is the version that holds.

The one case for sealing: a crawl space with a concrete floor, no ductwork, and humidity under 60 percent through summer. There, closed vents and a taped barrier are enough. If the floor is dirt or the space has HVAC equipment, skip sealing and go straight to encapsulation. 

How to Tell Which One You Have?

If a previous owner or contractor says the crawl space is encapsulated, check four things with a flashlight:

• Does the barrier run up the walls and stop a few inches below the sill plate?
• Are the seams taped, or overlapped and loose?
• Is there a dehumidifier, and is it running?
• Is there insulation on the foundation walls, or is it hanging between the joists?

Four yes answers mean encapsulation. Anything less is a sealed crawl space sold under the wrong name.

Not sure what you are looking at? Request a free crawl space inspection, and we will meter the space and tell you.

Frequently Asked Questions

Can I switch from a sealed crawl space to an encapsulated one later?

Yes. The vents are already closed. Upgrading means replacing thin plastic with a reinforced barrier, running it up the walls, taping seams, insulating the walls, and adding a dehumidifier. Most of the sealing work gets redone rather than built on.

Is a sealed crawl space the same as an encapsulated crawl space?

No. Sealed means closed vents and ground plastic. Encapsulated adds a wall barrier, taped seams, wall insulation, and humidity control. Some contractors use the terms interchangeably. Ask for the barrier thickness and whether a dehumidifier is included.

Can I seal my crawl space vents without a dehumidifier?

Not in this climate. Closed vents with no humidity control trap moisture. Building code treats a closed crawl space as unvented and requires a dehumidifier, mechanical exhaust, or conditioned air.

What is a conditioned crawl space?

An encapsulated crawl space supplied with air from the home’s HVAC system instead of a standalone dehumidifier. It meets the same code requirement. It works best when ductwork already runs through the space.