Practical Engineering: Holding the Roof Up

The morning following a recent heavy snowstorm, I got an emergency call about a roof collapse. It was, in fact, an example of what we engineers call “catastrophic failure” — a classic case of underdesigned (or undesigned?) eaves tie connections. Although these things don’t occur often, such a collapse serves as a reminder of wha t migh thappen if connections are not properly designed and executed in the field. This old, solidly built structural-brick building had full-size 3×8 attic floor joists at 16 inches on-center, with full 1-inch-thick plank flooring. (As it turned out, the sturdy attic floor saved the day, halting the fall of the roof assembly and preventing damage to the walls and ceilings below.) The