Mold in Air Ducts: How to Spot It, When to Worry, What We Can (and Can't) Do

Maryland summers are humid. Inside air ducts, that humidity meets dust, which means: mold has the conditions it needs. If you smell musty air every time the AC kicks on, you're almost certainly running biofilm through your supply registers.

What to look for (visible signs)

• Black or dark green growth on supply register grills
• Musty smell within the first 60 seconds of AC startup
• Condensation pooling in the supply trunk near the air handler
• Recurring upper-respiratory symptoms only at home, not at work

What an Eagle cleaning can fix

Surface mold on duct interiors, biofilm in the air handler, dust + mold mixture in the trunk — yes. We HEPA-vacuum it out, brush the duct walls, and apply EPA-registered antimicrobial fog. Post-cleaning IAQ Lab Report verifies mold spore count reduction.

What requires a licensed mold remediation contractor

If mold has grown into drywall, behind a vapor barrier, inside the home's structure (not just the ducts), or if the affected area exceeds 10 square feet — that's licensed remediation work and we will refer you. Maryland licenses mold remediation contractors separately from MHIC. We are not licensed for that work and won't pretend to be.

Aeroseal sealing if it keeps coming back

Some homes have leaky supply ducts pulling humid attic air across cooled surfaces. The condensation feeds repeat mold. Aeroseal duct sealing (a separate ~$1,500-3,000 service we don't offer but can refer for) closes those leaks at the source.