Why Are My Chimney Bricks Flaking and Crumbling?
Chipped, flaking chimney bricks are freeze-thaw damage. Why it happens so often in Northwest Indiana, how to stop it, and what repairs cost.
NWI Chimney · October 4, 2026
The short answer
Flaking, chipped or popping brick faces are called spalling. Water soaks into the brick, freezes, expands and breaks the face off. Northwest Indiana winters, with snow against the chimney and repeated freezing and thawing, make it one of the most common chimney repairs here. The fix is to stop the water first — crown, cap, flashing — then replace the damaged bricks ($350–$900 per area).
How spalling starts
Brick and mortar are porous. When rain or melting snow soaks in and the temperature drops below freezing, the water expands as it turns to ice and pushes the surface of the brick off. One winter does a little; years of it leave bricks with their faces missing and mortar washing out of the joints.
Why it's worse here
- Lake-effect snow piles against chimneys and melts in the day, refreezing at night
- Wind-driven rain off Lake Michigan soaks the side of the chimney facing it
- Cracked crowns let water straight into the top courses
- The wrong sealer — paint or non-breathable coatings trap moisture inside the brick and make spalling faster
Where to look
Bits of brick on the roof, in the gutters or on the ground around the chimney; brick faces missing near the top; mortar joints that are recessed or sandy; a white crust (efflorescence) showing water is moving through the masonry.
The fix and the cost
Repairs start at the top: crown sealing $250–$450 or a crown rebuild $600–$1,400, a cap $250–$400, flashing $300–$600. Then damaged bricks are replaced ($350–$900 per area) and joints repointed ($250–$550 per section). A breathable water repellent ($300–$900) on sound masonry helps it stay dry. If spalling covers most of the stack, a rebuild above the roofline may cost less over time.
More answers
Can I just paint or seal over spalled bricks?
No. Painting traps water in the brick and speeds up the damage. Damaged bricks need replacing, and only breathable repellents should go on masonry.
Is spalling an emergency?
Not usually, but loose pieces can fall, and it gets worse every winter. Fixing it in fall before the freeze is cheapest.
Does spalling inside the firebox mean the same thing?
Inside, it's usually heat or moisture damage to firebrick. Firebox repairs run $300 to $800.
Does My Chimney Need Rebuilding, or Just Repair?The signs a Northwest Indiana chimney is past repointing and needs a partial or full rebuild, and what each option costs.
Why Does My Fireplace Smoke Into the House?Smoke rolling into the room instead of up the chimney: the usual causes in Northwest Indiana homes, what you can try tonight, and the repairs that fix it.What Firewood Should I Burn in Northwest Indiana?Which wood burns hot and clean, how long to season it, how to tell if it's dry, and what not to burn — for fireplaces and wood stoves in the Region.Ready for a safer, cleaner chimney?
Same-week appointments, honest flat pricing, no scare tactics — and same-day emergency service when it can't wait. Licensed and insured.