Which cut works well on metal roof decking to prevent the decking from rolling away?

The triangular cut is effective on metal roof decking primarily because it creates a design that helps secure the material in place and prevents it from rolling away. This type of cut allows for an acute angle that can engage with the metal surface better than other types, providing stability.

When making a triangular cut into metal decking, the pointed end of the triangle acts as a pivot point, reducing the likelihood of the decking moving or rolling once the cut is made. This is crucial in firefighting scenarios where safety and control are paramount.

In contrast, diagonal, vertical, and horizontal cuts may not provide the same degree of stability or control over the metal decking. Diagonal cuts might create an unstable edge that could easily slide or roll, while vertical and horizontal cuts do not engage the material in a way that prevents movement effectively. Thus, using the triangular cut is a practical technique that promotes safety and efficiency during roof ventilation operations.