Volumetric and panelised construction, the difference

Both methods are often grouped together as off-site construction, and both move work from the site into a factory. The difference is how much work moves, and that decides almost everything about how the project runs.

Panelised construction

A panelised building is made from flat elements. Wall panels, floor cassettes and roof panels are manufactured in a factory, then trucked to site and assembled into the structure there.

The framing is faster and more accurate than stick building, and flat panels are easy to transport. Once the structure is standing, though, the building is still an empty shell. Plumbing, electrical, linings, joinery, tiling and painting all happen on site, by trades working in sequence, much as they would on a conventional job.

Volumetric construction

A volumetric module is a three-dimensional piece of the finished building. It leaves the factory with its structure, linings, services and finishes already in place.

On our projects, internal finishes and services are completed inside the factory before transport. A module arrives with a finished bathroom, a kitchen with its joinery fitted, and the wiring and plumbing tested. What remains on site is connecting the modules, closing out the joints and finishing the external works.

That is the real difference. Panelised construction moves the frame into the factory. Volumetric construction moves most of the building.

What it does to the programme

Because so much of the work is done in the factory, it can run at the same time as the site works rather than after them. While the base structure is being built, the modules are being built and fitted out.

That parallel programme is where the reduction of up to 60 percent comes from, as set out in [why the programme runs shorter](/blog/why-modular-programmes-run-shorter). A panelised build gains time on the frame but still runs most of its trades in sequence on site.

What it does to transport and the site

A flat panel travels easily. A finished module is a large load, which means the route is assessed, the dimensions are designed around what the road allows, and a crane sets each module in place. That process is described in [oversize loads and route assessment](/blog/oversize-loads-and-route-assessment).

The module is also structurally over-engineered to withstand that road transport. Once installed, it is over-built for service life.

The joints are the other site task. Where two modules meet, they are bolted together, the weather seal is formed and the services are connected and tested, as described in [the module joint and how it is sealed](/blog/the-module-joint-and-how-it-is-sealed).

Where the hybrid fits

Hybrid Volumetric Modular takes volumetric modules and marries them with the tried and tested base structure of conventional construction. The base structure answers the ground, so a sloping site does not force the dwelling up and away from level access.

The full method is explained in [what is Hybrid Volumetric Modular](/blog/what-is-hybrid-volumetric-modular).

Which suits special-use accommodation

Special-use dwellings carry a lot of detail inside them: accessible bathrooms, structural provision for ceiling hoists, reach ranges for controls, level thresholds. Volumetric construction lets that detail be built and checked under factory conditions, to a measured tolerance, before the module leaves.

On a project with several dwellings of the same type, the same details are repeated many times, which suits a factory well. That is why our work is volumetric, and why the hybrid base structure sits underneath it.

MADEmodular / MADEbetter.

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