When is a dry standpipe system typically used?

A dry standpipe system is typically used in areas prone to freezing temperatures. This is because dry standpipes are designed to be empty of water when not in use, preventing the water from freezing within the pipes during cold weather. By keeping the system dry, it eliminates the risk of ice forming and blocking the water flow when it is needed, which is crucial during fire emergencies.

In comparison, a wet standpipe system would be more suitable in climates where freezing is not a concern, as it maintains a constant water supply within the pipes. The other scenarios provided in the choices specify structural and geographical considerations that do not directly correlate with the primary use of dry standpipe systems. Specifically, while it might be common to use wet or dry systems based on building height or location, these factors do not specifically dictate the use of a dry standpipe system as effectively as the risk of freezing temperatures does.