roof deck

noun2

1. •
   The flat layer of construction materials to which the weather impervious layers are attached to a form a roof. It is known as the "roof deck", and they may be either level (for a "flat" rooftop) or sloped.

   • In multi-story commercial construction, the dominant form of deck (including roof deck) construction is composite steel deck. — 2024
2. •
   An upper deck of a ship that provides shelter for another deck underneath.

   • There are four decks under the main deck and three above, which are named the roof deck, the promenade deck, and the boat deck — 1913