In 2003 Rob Colquhoun established ‘Prebuilt’, a design-led prefabricated building outfit that endeavoured to distinguish itself from traditional kit / transportable building companies by offering custom prefab homes.

A major difference between Prebuilt and those that came before was the introduction of the architect into the design process, which meant each of their modular homes benefited from a custom design. Rather than forcing a standard ‘off the shelf’ transportable building to suit a variety of site orientations and client briefs, Prebuilt worked with, and from, an architect’s drawings to incorporate the needs of individual clients and sites.

Take Inverloch House for example, a three bedroom home built on top of a hill in a coastal region of Victoria. The home was designed by Ramon Pleysier and Berit Barton of Pleysier Perkins Architects (PPA) with consultation from Prebuilt over eight weeks, which included everything from site inspection to council documentation.

Working with the architect enabled Prebuilt to combine the benefits of offsite building manufacturing with the idiosyncratic nature of architect-led projects.

One key challenge faced by Prebuilt at Inverloch, as with the case with nearly all modular buildings, is that their prefab modules are built with a suspended floor, meaning that a significant subfloor space needs to be incorporated in order to meet BCA requirements.

A suspended floor also runs the risk of looking “less rooted” with the surrounding landscape than one with concrete slab floor, but clever material selection and design review by PPA and Prebuilt enabled the project to meet BCA requirements and also look embedded within the coastal Victorian site.

PPA and Prebuilt chose to orient Inverloch House to the site with a rammed earth garage that also formed the plinth for the rest of the project to sit on.

The house comprises three modules, manufactured in the Prebuilt factory over 12 weeks, that sit within and on top of the custom rammed earth wall. While the wall was the only portion of the project built onsite it was also the point for the rest of the home to articulate from.

The three modules of the 300sqm house are arranged around an internal courtyard, offering shelter from the prevailing winds and a place for family congregation. It has a smaller west-facing deck for outside meals in winter and an internal fire place for when the weather is more suited to interior living.

The project’s material palette is also very site specific and the team incorporated heavy insulation, double glazed windows and external sun shading devices to combat the location’s harsh weather.

While the speed and quality of the Inverloch House construction demonstrates the growing sophistication of modular housing design, its relationship with the landscape also reveals the ubiquitous role of the architect in design of quality, site-specific architecture.

Companies like Prebuilt understand this role, and are steering the prefab movement in new and exciting directions.


Colorbond Corrugated Iron #0.42 Standard range (in Woodland Grey)

Natural Shiplap spotted gum

Glasswool R2.7 wall batts 90mm

Glasswool R6.0 Ceiling Batts

Spotted Gum 135x32mm with clear decking oil coating

RHS Galvanised steel, Silver Top Ash rough sawn slat screens, Louvretec opening roof system

Undertaken by Rammed Earth Enterprises

Hardwood chunky timber frames and internal frameless window

Rylock custom design no reveal equaliser aluminium frame (in custom black)

Argon filled Low E double glazed glass

Smarter Timbers Flooring 190mm wide Hand Scraped engineered oak floorboards (15mm thickness)

HVAC System
Art Cool mirror split system with condenser units
Nobo heater (hardwired),

Cheminee Phillippe Radiante 700 woodheater