Look for cracked or crumbling mortar between your bricks, especially on the weather-facing side of your chimney. If you can see gaps in the mortar joints or notice pieces falling to the ground, you need repointing.
White staining on your bricks (called efflorescence) is another clear sign. This happens when water gets into the mortar, dissolves salts, and carries them to the surface as it evaporates.
Inside your home, water stains on ceilings near the chimney or in your attic are red flags. If you can see daylight through mortar joints when looking up your chimney, that’s an immediate concern that needs professional attention.