The most obvious signs are water stains on your ceiling or walls near the fireplace, especially after heavy rain or snow. You might also notice dampness inside your firebox, a musty smell coming from your fireplace, or white staining on the outside of your chimney. Less obvious signs include rusted damper or firebox components, wallpaper peeling near the chimney, or efflorescence (white chalky deposits) on your chimney’s exterior masonry. Sometimes you’ll hear dripping sounds inside the chimney during storms. If you notice any of these signs, it’s worth having a professional take a look before the problem gets worse.