Prefab, modular, and ADU projects come with a surprising amount of terminology—and much of it is used inconsistently. This glossary is designed to help people compare options more confidently and better understand how builders, manufacturers, and jurisdictions talk about prefab construction.
Prefab is a broad category. Modular is one specific type of prefab construction.
An ADU is a zoning classification. A tiny home describes size and form factor.
Manufactured homes follow HUD standards. Modular homes follow local building codes.
Turnkey usually means one primary team manages most phases. Design-build may still involve multiple coordinated parties.
Prefab involves off-site fabrication. Site-built homes are constructed almost entirely on the property itself.
A residential structure inspired by agricultural or post-frame buildings, often featuring open layouts and simplified forms. Some are site-built while others incorporate prefab or modular systems.
A very small residential structure, often under 400 square feet. Tiny homes may be built on foundations or trailers and are regulated differently depending on jurisdiction.
A housing type generally referring to factory-built homes constructed before modern manufactured housing standards were introduced in 1976.
Traditional construction where most or all work happens directly on the property rather than in a factory.
A building designed to produce as much energy as it consumes over the course of a year.
A structural system using large posts or poles rather than conventional framing. Common in agricultural buildings and some barndominiums.
The process of adjusting design or material selections to reduce cost while attempting to maintain functionality.
A formal modification to the original construction agreement involving changes in cost, scope, materials, or schedule.
A permitting process where a project is automatically allowed if it meets existing zoning and code requirements.
A legal right allowing someone else to use a portion of a property for a specific purpose, such as utilities or access.
Fees charged by local governments to offset infrastructure impacts from new development.
An on-site wastewater treatment system commonly used in rural properties without municipal sewer service.
An engineering analysis evaluating soil conditions, stability, drainage, and load-bearing characteristics.
The process of converting a shed-like structure into a habitable residential space, subject to local building and zoning codes.
A home pre-configured or designed to support integrated technology systems such as lighting, climate, security, and automation.