Frame constructions have been rigorously tested to simulate the home and transportation environments for improved durability. Components are secured with combinations of glue, blocks, interlocking panels and staples. Seats and back spring rails are cut from mixed hardwood and engineered lumber. High-resiliency foam cushions wrapped in thick poly fiber. Smooth platform foundation maintains tight, wrinkle-free look without dips or sags that can occur over time with sinuous spring foundations.