Which of these is an example of a non-stationary load that a roof deck must support?

A non-stationary load is one that can change over time or is not consistently present on a structure. An installer's mobile equipment on the roof is indeed an example of a non-stationary load because it is not fixed in place and can be moved around, unlike permanent installations. This means that when the equipment is on the roof, it introduces a load that can vary in location and intensity depending on where the equipment is situated.

On the other hand, permanent roofing materials, heavy snow accumulation, and wind uplift from storms represent loads that, once applied, can be considered stationary or predictable in nature for the duration of time they are present. Permanent roofing materials are fixed and designed to stay in place, while heavy snow may accumulate but is typically predictable based on seasonal weather patterns, and wind uplift, although dynamic during storms, is a load that is consistently acted upon the roof in a directional manner during those specific events.