Supporting multiple mats

A support structure for retaining a reinforcing bar in stacked layers comprising:

• a first support structure retaining a first reinforcing bar for a first mat;
• and
• a second support structure retaining a second reinforcing bar for a second mat, wherein said second support structure comprises:
• a first layer engaging portion, wherein said first layer engaging portion comprises one or more reinforcing bar receptacles;
• a second layer engaging portion, wherein said second layer engaging portion comprises one or more reinforcing receptacles sized to fit said second reinforcing bar for said second mat, wherein one of said one or more reinforcing receptacles comprises a channel open to receive said second reinforcing bar, wherein said channel comprises a first portion open to the top of said second support structure and a bar retaining portion, wherein said channel is defined by sidewalls that extend radially outward from an inner end receptacle of said one or more reinforcing receptacles, wherein retaining features are disposed on the walls of said channel so that a width of an opening to said bar retaining area is smaller than a width of said bar retaining area, wherein said sidewalls spread so that said second reinforcing bar can pass said retaining features and rest in said bar retaining portion as said reinforcing bar moves down said channel;
• and
• a support portion connecting said first layer engaging portion and said second layer engaging portion, wherein said support portion comprises legs that support said second layer engaging portion and provides an offset from said first layer engaging portion.