According to the National Park Service, “A new exterior addition to a historic building should be considered in a rehabilitation project only after determining that requirements for the new or adaptive use cannot be successfully met by altering non-significant interior spaces.” There are many schools of thought regarding additions to a historic property. The National Park Service guidance has three guidelines for an addition. They are: “preserve significant historic materials, features and form; be compatible; and be differentiated from the historic building.”
1. Do I need to make sure my addition is in keeping with my home, or be different enough to know it’s not part of the original structure?
Both. The easiest way to achieve all three guideline standards is to maintain the materials and general form lines from the original building while altering the window pattern or simplify the detailing. The National Park Service link below gives a great overview of how to approach an addition to a historic property.