In Australia’s capital cities in particular over the last 30 years or so, the speed in which commercial, civil, governmental and high-density residential buildings are completed has increased dramatically.
Everywhere you look, skylines are being transformed by the ‘sudden’ appearance of new buildings. And this perceived ‘suddenness’ is partly due to the wonders of prefabricated construction — large components being made offsite, shipped to site and erected in a shorter timeframe than it would via traditional bricklaying or similar techniques.
But this isn’t new. Prefabricated or modular construction has been around for hundreds of years. Or thousands of years, really — Roman forts were essentially comprised of a series of ‘panels’ made by placing mortar and stone inside wooden frames, which were then tilted into place.
Fast-forward to the 1800s and the Eiffel Tower is constructed in pieces offsite, shipped to site and assembled. In fact, no drilling or shaping of beams was done onsite; if a component was incorrectly made, it was sent back to the fabrication origin on the outskirts of Paris to be corrected or replaced by a correctly made section.
Prefabrication as a design and construction concept wasn’t always just reserved for grander designs. For private residential applications, simple prefab modular cottages were built in England in the 1600s to be shipped to the United States for accommodating the new colonists, for example. And in the 1800s in Australia, several cottages were made and shipped in the same manner for a similar purpose.
This set a precedent for home design and manufacture for many years to come, particularly in times of booming population growth, tough financial times or sometimes the two combined.
Not long after the Eiffel Tower’s completion, the first precast concrete panel residential towers were built in Liverpool, England. And not long after that, Sears, Roebuck and Company from Chicago were presenting bungalow and mobile homes in a catalogue of over 400 designs for offsite manufacture and shipment to any spare block in the USA, essentially introducing the ‘kit home’ to the residential market.
In the aftermath of both World Wars, the concept of prefabricated housing went on to help solve the housing shortage problem in Europe for hundreds of thousands of people. And the onset of the Great Depression also saw prefabricated homes as a solution for the majority of the American population who couldn’t afford anything above the average standard home cost of around $5000 USD. With this, by the time the 60s rolled around, prefab and mobile housing accounted for 15% of the US’s housing mix.
The Real Value
In addition to quality, it is the cost savings and construction efficiency that prefabricated/modular homes brought to developers, builders and in turn purchasers.
Here are a few positive points that should be endearing prefab construction to more home builders, construction companies and architects:
• Eco Friendly
All offsite-made components are made to exact measurements, with oversize materials wastage kept to a minimum. And compared to onsite construction, the preset sizes of the design elements and the fact that panels cover extra vertical square metreage at the site mean that the use of bonding and fastening materials is reduced, again reducing wastage and packaging waste.
Also, a prefab panel requires a lot less water for bonding materials like mortar.
• Financial Savings
Onsite installation team size is reduced with prefab panels, whereas several brickies would have been required to build a wall (literally) form the ground up. And in addition to fewer personnel, panels are erected quickly, to result in an entire wall, partition of floor within minutes, not hours.
Modular structures such as kit buildings are easy to disassemble and move to another site. With this, if an occupant is happy with the layout and size of their dwelling, the only expense for owning the same structure on a property at a different location is the relocation service itself and the labour to make sure that utilities are built and connected.
And when kept in the same place, a modular structure can be extended whilst maintaining a more deliberate, integrated and architectural appearance and function.
• Consistent quality
With offsite concrete setting via design software, each component is reproduced exactly the same without any human error. And compared to brick construction with its potential for human error at every layer of bricks laid, a prefab panel is straight and flush every time, from the bottom to the top.
• Shorter construction time
With a crane and a small team on the ground, again, the panels are installed at a faster pace than brick-built walls. For larger apartment projects, for example, these days it’s common to have the main shell rise to completion in a far shorter time than it takes to do internal fit outs like services installation or joinery work.
Indoor manufacturing of panels and other components is done under strict and consistently manageable conditions, away from variable weather conditions.
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