Modular box spring assembly

In a box spring unit having a frame, lateral slats mounting spring units and protective cover, the improvement comprising:

• a. a higher density of lateral supporting slats adjacent the lateral center line of said assembly, at least two of said slats adjacent to lateral center line being nested in a reinforced U-shaped metal member;
• b. a higher density of spring units adjacent said lateral center line of said assembly said spring units comprising formed wire torsion bars having two body portions interconnected by a primary torsion bar, the springs being oriented such that the primary torsion bars of the spring adjacent the lateral center line are parallel to the supporting slats, while those displaced from said lateral center line are perpendicular to the slats;
• and
• c. the density of said spring units adjacent said lateral center line is greater than the density of those displaced from said center line.

A box spring assembly comprising:

• a. a rectangular frame;
• b. lateral slats extending across said frame;
• c. formed wire torsion bar springs mounted on said slats, having two body portions interconnected at a primary torsion bar defining a longitudinal axis of said spring said longitudinal axis of the springs adjacent the lateral center line being parallel to the slats and the longitudinal axis of the springs displaced from the center line being perpendicular to the slats;
• and
• d. the lateral slats adjacent the lateral center line having a closer spacing than the slats adjacent to ends of the frame.