Look for visible signs like cracked or crumbling mortar joints, loose or displaced bricks, white staining (efflorescence) on the masonry surface, or any signs of water infiltration around the chimney base. Inside your home, check for water stains on walls near the fireplace, rust on the damper or firebox, or a musty odor that could indicate moisture problems. These often signal that exterior masonry damage is allowing water penetration. Significant vertical or stairstep cracks in the masonry can indicate structural stress or settling that requires immediate professional assessment to determine if rebuilding is necessary rather than surface repairs.