This code applies to all buildings except single-family homes and townhouses up to three stories high. The 2021 IBC includes many significant changes, such as Puzzle rooms (escape rooms) are now defined and regulated as special entertainment venues requiring compliance with Section 411 and special exit requirements. When determining the number of monitoring areas allowed in a building, each section separated by one or more firewalls is now treated as a separate building. In Group E facilities, all classrooms up to 20,000 cubic feet must have improved classroom acoustics in accordance with ICC A117.1. Requirements for Type I, II, III, and IV exterior wall composite metal materials and systems (MCM) have been simplified and sprinklers have been eliminated. The use of intermodal shipping containers as structures is now specifically addressed by provisions intended to supplement the existing IBC requirements.