HVAC & Cooling

Bathroom Exhaust Fan Dripping Water? Find Out Whether It Is Condensation or a Leak

A bathroom fan should remove humid air, not drip it back into the room. In cold weather, steam can condense inside an uninsulated or sagging duct and run back to the grille. Water can also enter through a damaged roof cap or leak from a roof penetration above the fan. Because the housing, switch, and ceiling can become energized or damaged, turn the fan off and avoid touching a wet grille until you have ruled out an electrical hazard.

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Common Symptoms

  • Water drips from the fan grille during or after a shower
  • The bathroom ceiling is damp, stained, or soft around the fan housing
  • The fan runs but the room stays humid or steamy
  • Dripping is worse during cold weather, wind, or heavy rain
  • The fan grille has rust, mildew, or water marks

Most Likely Causes

  1. 1

    Condensation in a Cold or Sagging Duct

    Warm humid air can condense in an uninsulated duct, especially when the duct sags and creates a low spot that drains back toward the fan.

  2. 2

    Loose, Crushed, or Disconnected Vent Duct

    A loose duct connection can dump humid air into an attic while reducing airflow outside, allowing moisture to collect around the fan and ceiling.

  3. 3

    Roof Cap or Roof Leak Near the Vent Opening

    Rain can enter through a damaged vent cap, failed flashing, or roof defect and travel along the duct or ceiling framing to the fan.

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Quick DIY Checks

Caution

ELECTRICAL AND SLIP HAZARD: Keep hands away from a wet fan grille, switch, and nearby lights. Catch drips safely, dry the floor, and do not remove the grille while water is actively present.

Safety Warning

STOP AND CALL A QUALIFIED PROFESSIONAL if water reaches electrical wiring, the ceiling is soft or bulging, rain appears to be entering, or you see mold or burned wiring. Do not run a wet exhaust fan until it has been inspected.

  1. 1Turn the fan off at the switch. If water is near the switch, light fixture, outlet, or ceiling opening, leave the circuit off at the breaker and do not touch the grille.
  2. 2Place a towel or container below the drip and note whether it happens only after showers, only during rain, or in both conditions. That distinction helps separate condensation from roof-water entry.
  3. 3When the grille and surrounding ceiling are dry, check for rust, loose grille springs, staining, or a soft ceiling. Do not pull down wet drywall or reach into the housing.

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Repair vs Replace

✓ Worth Repairing

Most condensation issues are corrected by restoring a short, supported, insulated duct path that vents outdoors. Replace the fan only if its housing is corroded, wet, damaged, or too weak for the room after the moisture source is fixed.

Est. Repair Cost

$20–$180 for duct insulation, a clamp, or a replacement grille; more for roof work

Est. Replacement Cost

$250–$900+ for fan replacement, duct rerouting, ceiling repair, or roof flashing work

Recommended Tools & Parts

  • Insulated bathroom exhaust duct

    Use a duct size and material compatible with the existing fan and roof or wall cap; support it to avoid water-holding sags.

    $20–$55

    Buy on Amazon →
  • Fan timer switch

    A timer keeps ventilation running after showers without relying on someone to remember to return and switch it off.

    $18–$45

    Buy on Amazon →

Links are Amazon affiliate links (tag: fixitfastai-20). Prices are estimates.

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Frequently Asked Questions

Why does my bathroom fan drip only in winter?
Warm shower air can condense inside a cold attic duct in winter. A sagging or uninsulated duct lets that water collect and run back toward the fan.
Can I keep using a fan that is dripping water?
No. Turn it off until the source is identified. Water at a fan housing or switch can damage wiring and create an electrical hazard.