Vent flapping

Intermittent flap or rattle at an exterior hood or backdraft damper.

Listen for the trigger

Record whether the sound begins with water flow, heating, wind, appliance operation or a change in room pressure.

Locate without unsafe access

Compare rooms and accessible surfaces. Do not open energized electrical equipment or combustion appliances to chase a sound.

Create a useful recording

Capture several seconds before and after the sound, include a spoken location and note the equipment state.