Cracked crowns from wind and freeze-thaw cycles
Why it happens here
The crown is a concrete cap on top of the chimney. It takes the full force of the wind coming off the airport. Water gets into small cracks, freezes, and expands, which makes the cracks bigger. After a few winters, the crown is cracked all the way through.
Our approach
We rebuild the crown with crown mix, slope it away from the flue, and seal the bond break. A properly built crown sheds water instead of absorbing it. We also check the crown on every maintenance visit so we can catch small cracks before they turn into leaks.