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Modular Construction The purpose of this document is to bring awareness to an emerging method of construction.

INTRODUCTION: Modular construction is a well-known, familiar concept that has been used in the construction industry for years. However, it has just recently gained momentum throughout the United States due to its efficiency and timeliness in completion, which is a major benefit in the construction industry. General contractors and construction managers benefit from modular, prefabricated buildings, as each portion of the building is constructed in a factory setting before being delivered to the jobsite for completion. Areas prone to harsh, un predictable weather conditions, low population, or isolated locations such as islands, benefit from this type of construction because the structure is built indoors. Consumers may be familiar with bathroom pods, which is a common method in many residential and hospitality projects. While modular construction is not a new concept, it is gaining market share due to a list of contributing factors, including labor short age, cost control, rising interest rates, and compressed building schedules. These factors must be considered prior to designing to determine whether or not modular construction is the ideal approach.

THE GOOD NEWS: • IBC building codes have been adopted to govern structure and inspection guidelines. • The smaller, single responsibility scope of work is defined early in the construction schedule to align onsite construction with manufacturing resources for installation. • Details need to be clearly defined prior to manufacture. • The work site is a controlled environment; materials and personnel can safely enter a known workspace, improving safety and efficiency. • Production can be increased due to predictability of processes and repeated tasks. • Substrates are more likely to meet ANSI A108 requirements for flatness because of the use of specialized tools and assembly processes. • Schedules are more predictable since they are not reliant on site conditions or weather delays. • Many manufacturers employ in-house designers and engineers to coordinate owner and construction teams’ needs with modular construction requirements • AREAS OF CONCERN: • Currently, there are no ANSI A108 installation specifications nor TCNA Handbook details specific to modular construction. • Use of fiberglass, aluminum, or steel floor structures will require careful consideration and manufacturers’ technical assistance to provide guidance. • Wall structure may include smaller studs or unusual substrates. • Additional stress may be placed on the assembly during shipping and installation of the unit. • Additional accommodations for movement may be required. • Unqualified, or inexperienced, labor is installing tile finishes, including shower systems; as a result, large, repeated installation failures add to owners/specifiers’ reluctance to include tiled projects.

• Repair or warranty claims may require traveling great distances and may add unnecessary costs and flexibility in finishing projects. PREFABRICATED ASSEMBLIES Prefabricated (aka “prefab”) assemblies can be separated into three basic categories: 1. Prefab exterior wall panels with masonry veneer/ prefabricated exterior wall panels with tile facade I. Exterior wall veneer - manufactured in a factory where walls are framed, sheathed, water vapor systems, insulation and bonding materials are installed and tiled using thin brick, natural stone, ceramic tile, or cultured stone. The wall assembly is packaged, shipped to the site, and secured to the building. II. Prefab exterior façade - manufactured in a factory where walls are framed, sheeted, water vapor systems, and a porcelain tile/panel rain-screen system is attached. The wall assembly is packaged, shipped to the site, and secured to the building. 2. Prefab interior tiled wall panels I. This includes interior dry or wet walls, ceilings, wainscots, and splashes. Wet wall panels can be combined with a waterproof pre-assembled shower base, site-installed floor/base, or manufactured tub or shower base. The wall panel is packaged, shipped to the site, and secured to the wall. 3. Prefab shower assembly I. Examples of these include pre-assembled shower base, manufactured in a factory to size, shape, and drain configuration tiled, grouted, packaged, shipped to the site, and secured to the floor. RELEVANT DEFINITIONS: 1. Modular construction is a process in which a building is constructed off-site, under controlled plant conditions, using the same materials and designing to the same codes and standards as conventionally built facilities, but in about

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NTCA Reference Manual | 2024 / 2025

Chapter 1 | Pre- and Post-Installation Considerations