This first stage is ideal for homeowners who don’t have standing water, but are noticing musty smells, fallen insulation, or high humidity in the crawlspace. The goal here is to improve air movement when it helps and block off any unwanted airflow between the crawl and the living space above.

Key Actions:

• Install a humidistat-controlled exhaust fan in one of the vent openings. This turns on automatically when humidity rises (usually above 50–60% RH).
• Leave some vents open to allow makeup air to flow in from the outside when the fan runs.
• Seal all gaps and holes between the crawlspace and the home. Focus on plumbing and electrical penetrations, rim joists, and the crawlspace access hatch.
• Lay a basic ground vapor barrier (6-mil plastic sheeting) to reduce moisture rising from soil.

Why it works:

This setup helps pull out humid air when needed and keeps crawlspace air from infiltrating your home. It’s affordable, simple, and often effective in drier climates or homes with minor issues.

When to move to Stage 2:

If RH still rises above 65–70%, or you see condensation, mold, or musty smells persisting, it’s time for a more controlled airflow strategy.