Which of the following is NOT an indicator of spreading rafters?

The presence of cracks in interior ceilings running perpendicular to the outside wall does not necessarily indicate spreading rafters. While such cracks can be a sign of structural issues, they can also arise from various factors unrelated to the behavior of rafters, including settling of the foundation, changes in humidity leading to material expansion or contraction, or improper installation of ceiling materials.

In contrast, other indicators such as visible sagging in the roof, separation at the ridge board, and outward bowing of the walls are more directly associated with the actions of spreading rafters. Visible sagging often reflects a failure in the rafter system, indicating that the rafters may be spreading due to loads that they were not designed to manage. Similarly, separation at the ridge board suggests that the structural integrity is compromised, which can be a direct consequence of spreading rafters applying force inappropriately. Outward bowing of the walls can also result from the lateral forces exerted by rafters that are no longer properly aligned, pushing against the walls and causing them to deform outward.

Therefore, the correct answer indicates an option that is less directly related to the specific behavior of spreading rafters.