Final answer:
Building and zoning regulations usually determine the floor area of accessory structures like sheds or playhouses that can be built without a permit; often this is 200 square feet.
Step-by-step explanation:
The question asks about the maximum floor area for a one-story detached accessory structure, such as a shed or playhouse, that does not require a permit. Building codes and zoning regulations typically dictate this maximum floor area, including restrictions like building setbacks from streets and boundaries, the size and height of buildings, and the number of rooms. For such accessory structures, the permitted floor area without a permit is commonly 100 or 200 square feet, though this may vary by jurisdiction. The answer would depend on the specific regulations of the area in question. However, without specific jurisdictional context, the most common exemption threshold provided in building codes is 200 square feet.