Risk is generally defined as the probability of the occurrence of an event multiplied by the consequences, should the event occur. On brownfield projects, key risk areas include retroactive cleanup liability, regulatory compliance and permit approvals, and lender concerns about return on investment. These risks can generally be classified as inevitable, unlikely, or minimized/avoidable if managed properly. Contamination of environmental media such as soil, groundwater and surface water, and sediment has traditionally been the focus of environmental assessments of properties being considered for redevelopment. Significant costs and liabilities may also be associated with contaminated structures, hazardous building materials, residual wastes within the building system, and physical assets such as production equipment that is not part of the building system. Over the years, processes to assess and clean up contamination of environmental media have been developed. The American Society for Testing and Materials has developed standards of practice for screening property transactions and for conducting Phase I environmental site assessments and Phase II environmental site investigations. Most states have also developed programs and standards that address soil, sediment, and groundwater cleanup. While these programs and protocols have helped to facilitate the reuse of sites with contaminated environmental media, they do not comprehensively address the issues associated with wastes and contamination within the building environment. Conditions within the building environment must also be quantified before associated risks can be understood. The objective of this article is twofold. The first portion examines risk areas common to most brownfield projects where major structures are present. Next, a process of due diligence called the Building Decommissioning Assessment (BDA) is introduced. Developed for clients in the manufacturing sector, the BDA process defines a standard approach for conducting appropriate inquiry into building systems prior to redevelopment and reuse. The BDA complements, and in many cases can be performed in conjunction with, other pre-development investigations, including Phase I and II environmental site assessments, asbestos surveys, mold assessments, and property condition assessments. When applied properly, the six steps of the BDA yield information essential to quantifying risks associated with structures at brownfield sites. The second portion of the article examines two case studies where the BDA process has been implemented and, as a result, has revealed previously unknown environmental conditions, limited the liability of both the owner and financier of the property, and helped ensure compliance with applicable environmental programs.