What is a good indication of checking the core of a masonry wall?

A good indication of checking the core of a masonry wall is that the chimney is too low. This scenario suggests that there may be issues with the structural integrity or proper construction of the masonry wall. Specifically, when a chimney is not built to the proper height, it can indicate that the wall behind it may not have been constructed correctly, or there could be inadequate support, which could lead to problems such as insufficient air flow or improper venting.

In masonry work, the cores, or voids, within masonry blocks should be filled with grout or concrete to provide stability and strength to the structure. A low chimney could lead a contractor to inspect the core to ensure that it is appropriately filled and conforms to building codes and safety standards. Checking the core can also help identify any potential weaknesses in the construction that could affect the overall performance of the masonry wall.

The other options, while relevant to masonry walls and chimneys, do not specifically indicate a need to check the core. For instance, cracks in the chimney usually suggest settlement or structural issues, but they do not directly indicate the status of the core itself. A chimney that is too high is generally a result of design choices, not an indication of issues with the masonry core, and grout overlaps primarily relate