Prefabricated Homes and Buildings

What prefabrication means in practice

Prefabrication covers a range of systems, and the term gets used loosely. What they share is that the building’s components are manufactured to specification off site and assembled rather than constructed in place.

At one end, panelised systems arrive as flat wall and roof elements and are bolted or fixed together on site. At the other, near-complete volumetric modules arrive on a truck and are craned into position. Most projects sit somewhere between.

The practical distinction from precast is weight and access. Prefabricated panel systems are generally light enough to handle without heavy craneage, which is exactly why they work where a concrete panel could never be delivered.

It is worth being clear about what prefab is not. It is not temporary, it is not a Wendy house, and it is not exempt from building regulations. A prefabricated dwelling is a permanent building that must comply with SANS 10400 and be enrolled with the NHBRC like any other.

Where prefab is the right answer

Remote or difficult-access sites, where transporting bulk materials and running a long conventional build is impractical or expensive.

Site offices, site accommodation and welfare facilities on construction projects — a core use and one we understand from the contractor side.

Phased accommodation, where you need units now and more later, and want them to match.

Farm and agricultural buildings, staff housing, and structures where speed and function lead over bespoke design.

Where it fits less well: a bespoke architectural home with complex geometry, or a site where a conventional build is entirely practical and the client wants masonry mass. We will tell you when that is the case.

Foundations, assembly and the junctions

Prefabricated buildings are light, which reduces foundation loads but does not remove the need for a properly designed foundation on investigated ground. Light structures on poor ground still move, and a building assembled to tight tolerances shows movement more visibly than masonry does.

Assembly quality is what separates a good prefab building from a poor one. Components manufactured to tolerance still have to be set out accurately, levelled and fixed correctly. A frame that is out of square at the base is out of square all the way up, and the panels will not close properly.

Junctions are where these buildings live or die. Panel-to-panel joints, wall-to-roof junctions, window and door openings, service penetrations. Each one needs a designed weather seal and, where relevant, a movement allowance. Water getting into a panel system is far harder to trace and dry out than water in a masonry wall.

On the Garden Route the specific risks are wind-driven rain finding poorly sealed junctions, and coastal air attacking fixings and any exposed steel. Both are handled by specification and detailing rather than by hoping.

Insulation, services and finish

Most panel systems have insulation built into the panel, which is a genuine advantage over uninsulated masonry — but the performance depends on the specification and, again, on the junctions, where thermal bridging occurs.

Services need planning earlier than in a conventional build. Chasing a cable into a masonry wall is routine; cutting into a structural insulated panel after assembly is not. Conduit routes and penetration positions are a design decision, not a site decision.

Internal and external finishes are largely conventional — the building can be plastered, clad, painted or lined much as any other. A well-finished prefabricated home is not identifiable as one from the outside, which surprises people who associate the word with site huts.