By Krishna Loomba and Lee Craft
A plumbing riser is a single-line diagram (see above) representing how fixtures are connected to the plumbing system in a building. Plumbing risers are not expected to be dimensionally accurate; they simply convey information about the designer’s intended sizing and connections. With building information models becoming more popular, the Building Division has been receiving axonometric (isometric, diametric and trimetric) projections (see below) in lieu of plumbing risers. These projections typically complicate rather than simplify the plumbing plans. This requires the county reviewer to decipher intended locations and connection points in order to verify code compliance. This increases the review time considerably and is the reason why the Building Division requires standard single-line plumbing risers during permit application.