Mattress foundations and foundation corners, methods, and kits include a first side rail, a second side rail, a first end rail, and a second end rail. In one example, the rails join at corners to form the frame of the foundation and the rails may include at least a partial overlap between the rail the corners. The foundations and kits further include a plurality of slats. The slats may be of varying lengths. The invention may further include a method of assembling a foundation kit.

A bed frame includes a frame, bed legs, and a bed plank support frame. The frame includes two side boards, a head board, and a tail board. Respective bottoms of opposing sides of the two side boards are provided with a plurality of U-shaped connecting members, respectively. The bed plank support frame includes a plurality of support members. Two ends of each support member are connected to U-shaped connecting grooves of the corresponding U-shaped connecting members of the two side boards, respectively. The bed plank support frame is sunk when in use. After a bed plank is placed, there is a certain distance between the bed plank and the top of the frame, so that the frame can form four stop sides. After a mattress is placed on the bed frame, the mattress is restrained in the frame, not sliding.

Disclosed is a mattress foundation kit configured to be assembled by a user. The mattress foundation kit may include a plurality of rails, wherein each rail is a longitudinal member constructed of a structural foam core connected, for example by being permanently laminated, with at least one supporting material. Further, the mattress foundation kit may include a plurality of interconnecting members corresponding to the plurality of rails. Moreover, the mattress foundation kit may include a plurality of retainer clips attached along a side of at least two rails of the plurality of rails. Yet further, the mattress foundation kit may include a plurality of slats corresponding to the plurality of retainer clips, wherein the plurality of slats is configured to support a mattress, wherein each end of a slat is configured to detachably engage with a corresponding retainer clip.

An interconnector includes a plate and two pockets. The plate comprising a top and a bottom for contact with a beam. The pockets are formed on the top of the plate. Each of the pockets includes an opening. The openings of the pockets are located on opposite lateral sides of the plate. The openings allow the pockets to receive two bars in parallel to each other in substantially opposite directions.

An insert adapted to be inserted between a foundation of a bed and a mattress of the bed. The insert includes a frame having a first side rail and a second side rail spaced apart from the first side rail. A plurality of elongate upper slats extend between the first side rail and the second side rail of the frame at a first level with respect to the frame and are spaced apart from one another. A plurality of elongate lower slats extend between the first side rail and the second side rail of the frame at a second level located below the first level of the upper slats. Each lower slat is located below a gap formed between a pair of adjacent upper slats. A mounting member resiliently supports the ends of two adjacent upper slats and rigidly supports the end of a lower slat that is located below the gap formed between the two adjacent upper slats, whereby the firmness of a mattress overlying the insert can be selectively adjusted.