The Planning Board will hold its first public meeting of the new year at 7 p.m. Monday with two agenda items — a proposed office building expansion on Firmin Avenue, and the Heritage Crossing subdivision on East Main Street. The Firmin Avenue discussion will pick up a hearing on an application by Norman Real Estate Partners for a special permit to add about 156,000 square feet to an existing office building. The proposal includes 542 additional parking spaces. The board’s hearing on Heritage Crossing, a subdivision that would consist of five single-family homes at 43 and 57 East Main St., is slated for 8 p.m. The board will discuss the bonding submitted by the developer, Capital Group Properties. The meeting will be in the McAuliffe Hearing Room in the Town House, 17 Common St. Full story for BostonGlobe.com subscribers.