AS WITH ALL SPECIAL APPLICATIONS OF GENERAL principles, there are particular areas of concern when dealing with the design, construction, and maintenance of commercial, institutional, and high-rise buildings. This chapter will relate the principles previously stated regarding moisture migration, water vapor transmission, material properties, etc., to the special applications for these types of structures. Commercial buildings would include such occupancies as offices, retail spaces (including shopping malls), restaurants, and special purpose buildings such as business parks and light industrial facilities. Institutional buildings include hotels, hospitals, apartments, condominiums, schools, and prisons. Offices, hotels, condominiums, and hospitals are often designed with multiple floors in order to make the most use of available land. These mid and high-rise buildings also have particular requirements with respect to roofing, waterproofing, and curtain wall construction, such as the special exterior design wind pressures and internal pressurization arising from mechanical equipment or partially enclosed fenestration arrangements (Figs. 1–3). The best time to deal with moisture-related problems is during design and original construction using good design and construction practice related to roofing and waterproofing assemblies, including flashings, as well as the use of recognized industry standards such as The NRCA Roofing and Waterproofing Manual [1], SMACNA's Architectural Sheet Metal Manual [2], and the ASHRAE 2005 Handbook of Fundamentals [3].