Modular prefabricated houses: why the construction site is gradually moving into the factory

Modular construction is not new, but in recent years it has moved from temporary structures to permanent buildings: housing, dormitories, office blocks in industrial parks, port operations buildings. CGD works in this segment through prefabricated house models manufactured in Vietnam, including a set of models for a housing project in Darwin, Australia.

The biggest change is not the materials but the sequence

With on-site construction, the detailed design can be completed progressively while the structure is being built. Not so with modular. Every detail of a module must be fixed before the first module enters the production line, because correcting a module that has been produced means correcting the whole batch.

The consequences for the project owner: design workload is front-loaded, the time to approve the scheme is shorter, and any change after the design is frozen is expensive. In return, the on-site schedule is cut sharply and depends much less on the weather.

Four constraints that decide whether modular is feasible

Transport. Module size is limited by road clearances and transport permits, not by design. An oversize module can still be hauled, but the cost and paperwork will eat up the savings.

Cranes and assembly site. You need a crane position, a suitable working radius and enough laydown area for modules waiting to be installed. Cramped inner-city sites are often the reason a modular scheme is ruled out.

Joints. This is where all problems with water ingress, sound insulation and load transfer arise. Joints must be designed together with the module, not resolved on site.

Building services. Electrical, water and air-conditioning runs within a module need connection points accurate to the centimeter, because two modules installed side by side leave no room for adjustment.

When modular is worth it

Modular pays off when there are enough repeated units — worker housing, dormitories, and identical control room blocks across many projects. For one-off buildings with many variations, mold and production line setup costs usually do not pay back.

In logistics infrastructure, the strongest fit today is office and operations blocks in the yard, driver rest houses, and ancillary buildings with repeated designs. Warehouses and yards should still be built on site, because large column spans and ground load capacity are things modular does not yet handle well.

What the project owner should decide early

The decision between modular and on-site construction should be made at the project preparation stage, not left until construction drawing design. The two options produce fundamentally different sets of documents, and changing course midway means redoing most of the work.

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