Abstract: Mattress foundations and kits include a first side rail, a second side rail, a first end rail, a second end rail, and at least one center rail. The foundations and kits further include a plurality of slats of varying lengths. The invention may further include a method of assembling a foundation kit.

Abstract: A mattress leveling system designed to provide individually adjustable mattress heights, where mattresses of different firmness and thickness can be integrated into one bed with a level sleep surfaces sharing a common plane and held juxtaposed. Each mattress or mattress set is securely supported within a frame assembly with independently height adjustable legs. Users can integrate individual mattresses, which provide adequate firmness to meet the needs and desires of each of the users, forming one bed system customized to provide optimal comfort for both partners. An advantage of this design provides users with the ability to integrate into one bed, commonly available standard or non-standard adult size mattresses of differing thickness from different manufacturers, taking advantage of the latest sleep comfort technologies available on the market. Another advantage is the ability to exchange one mattress of the integrated bed without affecting the other mattress.