What does the term "platform frame" indicate in building construction?

The term "platform frame" in building construction refers to a framing method in which each floor of a building is constructed independently. Each floor is built as a separate platform, and the walls are then erected on top of these platforms. This design effectively acts as a firestop because it limits the vertical spread of fire within the structure. The platform frame allows for easier construction and is commonly used in residential buildings, as it simplifies the structural process and accommodates various architectural designs.

In this framing method, since the floors are built separately, the construction provides increased structural integrity and fire separations between the floors, which is crucial for life safety in the event of a fire. The walls constructed on each platform provide barriers that can help slow the spread of flames and smoke between different levels of a building.