Abstract: A recreational vehicle construction is constructed with a durable, open, and accessible subfloor, or subfloor frame assembly, placed between a skeletal chassis and the floor of the vehicle. The general structure of the subfloor includes a center portion and two outrigger assemblies on the flanks of the center portion. The subfloor frame assembly includes a pair of spaced basic beams secured to the underlying chassis, a plurality of upwardly extending spaced posts, and two overlying spaced apart center beams secured to the upper ends of said posts. The subfloor enhances overall stability and rigidity of the vehicle and increases storage space. The open and accessible design of the subfloor eases post-production installation of various components of the vehicle and also increases serviceability, thereby reducing production and service costs.