Walk onto any job site or into any factory today and you will hear "offsite", "modular" and "prefab" used almost interchangeably. They are related, but they describe different things, and knowing which one you are dealing with changes how a project should be modeled.
Offsite: where the work happens
Offsite construction is the umbrella term. It simply means that some part of the building is made somewhere other than its final location, usually in a controlled factory environment, and then shipped to site. Everything below falls under this umbrella.
Prefabrication: building the parts
Prefab usually refers to components: wall panels, floor cassettes, trusses, stair assemblies. They are made in the shop, trucked to site and installed piece by piece. Panelized light gauge framing is one of the most common examples, and a large share of our daily work.
Modular: building the rooms
Modular construction takes things further. Instead of flat components, the factory produces three-dimensional volumes, complete rooms or apartment units, often with finishes, plumbing and electrical already installed. On site they are craned into place and connected.
Why it matters in BIM
- Tolerances: a module has to meet its neighbour within millimetres, so the model must be built to that level of accuracy.
- Shipping limits: panel sizes and module dimensions are driven by trucks and cranes as much as by architecture.
- Sequencing: stacking, bunking and delivery order become part of the design, not an afterthought.
Whatever you call it, the direction is the same: more of the building made in the factory, and a model that has to be ready for manufacturing from day one.
Work with Bimnautics
Moving from site-built to panelized or modular? We can help you set up models that are ready for the factory.
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