Your question starts do I need? Here's how I look at it.
1. DWELLING UNIT. A single unit providing complete independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking and sanitation.
2. SECTION R317 DWELLING UNIT SEPARATION
3. R317.1 Two-family dwellings.
Dwelling units in two-family dwellings shall be separated from each other by wall and/or floor assemblies having not less than a 1-hour fire-resistance rating when tested in accordance with ASTM E 119. Fire-resistance-rated floor-ceiling and wall assemblies shall extend to and be tight against the exterior wall, and wall assemblies shall extend to the underside of the roof sheathing.
4. R317.1.1 Supporting construction.
When floor assemblies are required to be fire-resistance-rated by Section R317.1, the supporting construction of such assemblies shall have an equal or greater fire-resistive rating.
There are some exceptions but I can't comment if those apply. Depending how it's built the answer is maybe.