1. A method for performing a quantity takeoff computation, the method comprising: organizing a CAD drawing into a hierarchical representation that includes at least one object family associated with a plurality of object types, wherein each object family corresponds to a different object, each of the plurality of object types corresponds to a different variation of the different object, and each instance of each object type associated with an object family represents a drawing object present in the CAD drawing; receiving a selection of a first object family; parsing the first object family to determine the plurality of object types associated with the first object family; creating a takeoff object for each of the plurality of object types associated with the first object family; identifying, via a processor, instances of each of the plurality of object types associated with the first object family, wherein each instance is associated with one or more object properties and is identified by a different instance globally unique identifier (GUID); and quantifying the instances and the one or more object properties associated with each instance to produce a quantity takeoff value.