This chapter explores how the size and details of structural members affect the architectural qualities of space. Designing and detailing exposed structural members offers an opportunity for structure to exhibit qualities of fineness or, conversely, heaviness. For example, in many situations solid beams can be replaced by trusses that use less material and are visually lighter and more transparent as a consequence of their far finer and widely spaced members. Of course, it must be remembered that the disadvantages of this type of construction include greater fabrication costs, vulnerability to corrosion and fire damage, and increased maintenance for cleaning and painting. The chapter focuses on achieving a wide spectrum of architectural qualities. Provision of particular architectural qualities is a fundamental characteristic of any successful work of architecture. Using five pairs of common contrasting pairs of qualities: simplicity-complexity, open-closed, lightweight-heavy, soft-hard and elegant-rough.