Pergola Construction in Novato, CA: Span, Posts and Where the Structure Lands

Posts are the first real constraint in pergola construction in Novato, CA, and they get decided by arithmetic rather than preference. A homeowner describes the space they want covered. 

The beam that has to cross it reaches only so far before it begins to sag under its own weight, and the number of posts follows from that distance. How open the finished structure feels and where people walk both sit downstream of that one calculation.