A pergola is a structure built to provide overhead shade.  It is usually supported on four sides by vertical posts that hold in place a lattice of wooden members.  Some pergolas are attached to the house at one side with a ledger board. 

If you plan to do this, make sure you take all the same precautions to maintain a watertight connection using flashing and caulking.  The sizes of the overhead members can vary but the lowest boards in the strata will be the heaviest.  Beams attached on opposite sides of the structure will support one or more layers of cross members of reduced size.  The spacing and size of these members or louvers will dictate the amount of sunlight that is allowed to penetrate and the visual mass of the structure.  Sometimes vines are trained to grow through the latticework to provide a lush natural canopy. 

Pergolas only must be designed to be self-supporting because it will not function as a floor and it will not collect snow.  Still you must be sure that it can resist wind uplift and is securely attached to the floor.