Described herein is a process and system for constructing three-dimensional (3D) representations of roof structures. The system can create representations of roof structures of arbitrary complexity and can create representations of dependent roof structures such as dormers. The system can create representations of roof structures that conventional methods cannot create, such as roofs with edges that are not coplanar, roofs with faces that do not connect to exterior edges, roofs composed of sub-structures, or roofs with dependent structures such as dormers.