What is prohibited in the center third of solid sawn beams?

In solid sawn beams, the center third is a critical area because this section experiences the highest levels of stress and bending when the beam is loaded. Boring and notching can significantly weaken the structural integrity of the beam, making it less able to support loads safely.

Boring holes through the beam in this area can create points of weakness where the material is removed, potentially leading to failure under load. Similarly, notching, which involves cutting away a section of the beam, compromises the beam's ability to resist bending and shear forces.

The prohibition of modifications, such as boring and notching, in the center third is grounded in engineering principles that prioritize safety and structural reliability. This restriction helps prevent potential structural failures that could arise from altering the beam's original design strength in its most vulnerable area.

While other options may seem plausible to mitigate concerns, the overriding concern is preserving the beam's structural integrity, which is why both boring and notching are prohibited.