For decades, builders put vents in crawlspace walls so outside air could dry them out. That works in a dry climate. In a North Carolina summer, the outside air is hot and full of moisture. When it flows into a cooler crawlspace, that moisture condenses on joists, ducts, and insulation, the same way water beads on a cold glass.
Add red clay soil that holds water after every storm, and you get a crawlspace that stays damp most of the year. Over time that means mold on the framing, insulation falling from the floor, rusting duct connections, and a musty smell in the house.
Encapsulation reverses the approach. Instead of letting outside air in, we seal the crawlspace off: a heavy vapor barrier over the ground and up the walls, sealed seams and piers, closed vents, and a sealed access door. A dehumidifier then keeps the air inside at a safe humidity level.
If water is pooling under the house, that comes first. Drainage and a sump pump get the water out, and the barrier keeps it from coming back as vapor.
The result is a crawlspace that stays dry year-round, framing that stays solid, and cleaner, less humid air in the rooms above.