When the new junior high in Waterford Maine opened for the first time, a teacher observed that the ceiling was deflected and that dust was coming from the ceiling. The school was evacuated and a short time later the roof to collapsed. Wood products expert witness Rubin M. Zallen, P.E., determined that drifting snow increased the snow load and caused the collapse. In his report, Zallen offered these definitions:
The allowable load is also called the safe load; it is the ultimate load divided by an appropriate safety factor. The ultimate load itself may be a collapse load or may be a yield load beyond which excessive deflections would render the member unusable.
Dead load is the weight of the building components.