Look for water stains on your ceiling or walls near the fireplace, especially after heavy rain. You might notice dampness inside your firebox, a musty smell coming from your fireplace, or even see water dripping during storms. Other signs include white staining on your exterior chimney bricks (called efflorescence), crumbling mortar joints, or rust on your damper or firebox. Sometimes you’ll hear dripping sounds inside your chimney during rain, or notice that your fireplace smells worse in humid weather. Don’t wait if you see any of these signs. What starts as a small stain can quickly become major structural damage, mold growth, and expensive repairs throughout your home.