When can spiral stairways be used as a means of egress?

Spiral stairways can be used as a means of egress under specific circumstances detailed in building codes. The correct response accounts for all acceptable uses of spiral stairways as a means of egress.

They are permissible within dwelling units because residential buildings often have more flexibility in design, allowing for space efficiency through features like spiral stairways. Additionally, in spaces not exceeding 250 square feet, this design is recognized due to the manageable size and occupancy load, which allows for the effective use of a spiral stairway without compromising safety. Technical production areas may also utilize spiral stairways depending on how those spaces are structured and the specific regulations in place concerning occupancy, safety, and overall design.

In contexts where these sizes and types of buildings are involved, building codes typically offer the allowance for spiral stairways to be included as a means of egress, provided they meet specific criteria related to width, rise, and exit access of the stairs. Thus, acknowledging all the scenarios listed reinforces the answer's correctness.