This Krugerville chimney needed work at both ends. Up on the roof, the crown had cracked and was shedding material, leaving the flue open to the weather. Inside, the firebox had cracked through the back wall and along the corner masonry.
The two problems are related more often than homeowners expect. Water that gets past a failed crown travels down the flue and into the masonry, and freeze and thaw cycling does the rest. Fixing one without the other buys you a season.
Resurfacing the Firebox
The firebox was cleaned back to sound material so the full extent of the cracking could be seen. A crack ran through the corner where the back and side walls meet, which is where movement concentrates, and the back wall had opened along a mortar line.
Rather than patch individual cracks, we resurfaced the walls and floor with a parge coat. That seals the joints as one continuous surface instead of leaving a line of repairs that will each move independently. The masonry repair was taken across the whole firebox for that reason.
Crown and Cap
The crown had cracked through and lost surface material, and there was no cap over the flue. That combination puts rain straight into the chimney and gives birds and animals an open route in.
We fitted a top mounted cap over the crown with mesh screening, sized to the flue and set to shed water clear of the brick. It protects the crown underneath from further weathering as well as keeping the flue dry.
