Named the "box" pergola as it is designed with rows of blockings between rafters which gives the appearance of oblong or square boxes. This type of pergola is becoming more and more popular and is not that difficult to build.
This woodworking project uses pine that has been treated for the outdoors and also for ground application. The specified lumber sizes are easy to find at your local lumber yard and helps make this an easy and inexpensive project. This plan can be found at Buildeazy.com - http://www.buildeazy.com/pergolabox.html or go to FreeWW.com to browse the rest of the free pergola plans - http://www.freeww.com/pergolas.html