Signs your crawl space needs encapsulation

Signs you notice upstairs

• A musty smell. A large share of the air in your living space rises from the crawl space through gaps around pipes, ducts and the subfloor. If it is damp down there, you are breathing it.
• Sticky, humid air in summer. Louisville summers push warm, wet air through open vents into the space under the house.
• Cupping hardwood floors. Wood floors take on moisture from below and cup.
• Soft spots or sagging floors. Long enough, and joists soften and floors dip. That is the expensive stage.
• Cold floors in winter. A vented crawl space brings in freezing air in winter, and the floor above feels it.

Signs you see under the house

• Condensation on ducts and pipes. Humid summer air condenses on the coldest surfaces first: metal ducts, water lines, then the wood.
• Wet or fallen insulation. Fiberglass batts soak up moisture, sag and fall out of the joist bays. Wet insulation holds water against the subfloor.
• Mold on joists or subfloor. White, green or black growth on the wood means humidity has been above 60 percent for a long time.
• Torn or bunched plastic. Old sheeting that has come apart leaves bare dirt, and ground moisture rises out of bare dirt around the clock.
• Standing water or mud after rain. That is a drainage problem first. See crawl space waterproofing.

Check the humidity yourself

A battery hygrometer from a hardware store, left on a joist near the middle of the space for a week in summer, tells you where you stand. Read it in the evening and take the highest reading. Keep a crawl space under about 60 percent relative humidity; the humidity guide explains the numbers.

What encapsulation fixes, and what comes first

A crawl space encapsulation seals the space off from the ground and the outdoor air: liner across the floor and up the walls, seams sealed, piers wrapped, vents closed, and a dehumidifier sized to the space. It stops the moisture that rots wood, feeds mold and warps floors.

The order matters. Water first, with drainage and a sump. Mold treated next, by an IICRC-certified company. Ruined insulation out. Soft joists repaired. Then the seal. Sealing a liner over water or mold is how problems get created, not fixed.

When a vapor barrier is enough

If the crawl space is dry after heavy rain, the wood is clean and the insulation is in place, a vapor barrier may be all it needs. We install them, and we will tell you when that is the right job.