Modular buildings and modular homes are sectional prefabricated buildings, or houses, that consist of multiple sections called modules. “Modular” is a method of construction differing from other methods of building. The module sections are constructed at an off site (sometimes, remote) facility, then delivered to the intended site of use. Complete construction of the prefabricated sections are completed on site. The prefabricated sections are sometimes lifted and placed on basement walls using a crane, the module prefabricated sections are set onto the building’s foundation and joined together to make a single building. The modules can be placed side-by-side, end-to-end, or stacked, allowing a wide variety of configurations and styles in the building layout.
Modular buildings, also called prefabricated homes or precision built homes, are built to the same or higher building standards as complete on site stick built homes. Modular homes are built the same and considered the same as a stick built home. Material for stick built and modular homes are the same. Modular homes are not doublewides or mobile homes. First, modular homes do not have axles or a metal frame, meaning that they are typically transported to their site by means of flat-bed trucks. Secondly, modular buildings must conform to all local building codes for their proposed use, while doublewides and mobile homes have metal under framing. Doublewides and mobile homes made in the United States, are required to conform to federal codes governed by HUD (U.S. Department of Housing and Urban Development).
Modular components are typically constructed indoors on assembly lines.
Modular buildings are argued to have advantages over conventional buildings, for a variety of reasons.
- Speed of construction/faster return on investment. Modular construction allows for the building and the site work to be completed simultaneously. According to some materials, this can reduce the overall completion schedule by as much as 50%.
- Indoor construction. Assembly is independent of weather, which can increase work efficiency and avoids damaged building material.
- Ability to service remote locations. Particularly in countries in which potential markets may be located far from industrial centers, such as Australia, there can be much higher costs to build a site-built house in a remote area or an area experiencing a construction boom such as mining towns.
- Low waste. With the same plans being constantly built, the manufacturer has records of exactly what quantity of materials are needed for a given job. With the consistency, builders can design systems that use common lengths of lumber, wallboard, etc, cut items with maximum efficiency, or be able to order special lengths in bulk. While waste from a site-built dwelling may typically fill several large dumpsters, construction of a modular dwelling generates much less waste.
- Environmentally friendly construction process. Modular construction reduces waste and site disturbance compared to site-built structures.
Flexibility. One can continually add to a modular building, including creating high rises
The materials used in modular homes are typically the same as site constructed homes. Wood-frame floors, walls and roof are often utilized. Some modular homes include brick or stone exteriors, granite counters and steeply pitched roofs. Modulars can be designed to sit on a perimeter foundation or basement.
Typically, modular dwellings are built to local, state or council code, resulting in dwellings from a given manufacturing facility having differing construction standards depending on the final destination of the modules.
Modular homes are designed to be stronger than traditional homes by, for example, replacing nails with screws, adding glue to joints, and using 10-20% more lumber than conventional housing] This is to help the modules maintain their structural integrity as they are transported on trucks to the construction site; however, it is difficult to predict the final building strength since the modules need to endure transportation stresses that traditional homes never experience]
The insulated concrete forms are modular units that are dry-stacked (without mortar) and filled with concrete. Insulating concrete forms has an acceptable ductility if used in high seismic risk zones. 
When FEMA studied the destruction wrought by Hurricane Andrew in Dade County Florida, they concluded that modular and masonry homes fared best compared to other construction.
Modular buildings can be assembled on top of multiple foundation surfaces, such as a crawl space, stilts (for areas that are prone to flooding), full basements or standard slab at grade. They can also be built to multi-story heights.
Exterior wall surfaces can be finalized in the plant production process or in the case of brick/stone veneers, field applications may be the builders’ choice. Roof systems also can be applied in the field after the basic installation is completed.