18 Prefabrication
Working on site is a slow, complex and messy business. But there is another way to build that avoids some of the complexity and mess—assembling a building from a kit of parts prepared beforehand. This type of building works in a different way from traditional building, and it has proved hugely successful in certain types of structure, especially industrial buildings, since Victorian times.
People tried applying the idea of prefabrication to building as long ago as the Middle Ages, assembling timber-framed houses by constructing parts of the frame in the carpenter’s workshop and then carrying them to the site where they were “raised” into position.
These early prefabricated houses were a success, but each frame was custom-made, every building was unique. The big step in prefabrication, the step that really cut down the labor and made building a matter of assembling parts, was to make the parts interchangeable. This step was first taken in the 19th century, when the labor-saving machines of the industrial revolution could make building still faster and more standardized. The greatest advocate of this way of building was the British gardener and designer Joseph Paxton.
The great greenhouses Joseph Paxton worked at the Royal Botanic Gardens at Kew before going to Chatsworth to become the head gardener on the Duke of Devonshire’s estate. While at Chatsworth, Paxton developed his flair as a designer of greenhouses, noting that the existing houses, with their thick glass and heavy timberwork, were gloomy inside. So he began to develop new glasshouse structures with thin glazing bars, wooden frames and columns made of cast iron. His Lily House—almost 30 meters (100 ft) in length—and his Great Stove (1836–40), an enormous hothouse, were two of his triumphs.
New technologies In the course of this work, Paxton realized that he could stretch existing technology. For example, he was impressed by the work of Robert Chance, a glass manufacturer who had improved the cylinder glass-making technique so that he could produce sheets of glass nearly 1 meter (3 ft) in length. He pressed Chance: if the glazier could make sheets 1.2 meters (4 ft) long, Paxton would place a large order. Chance responded with 1.2-meter sheets.
Paxton also invented machines for shaping sash bars, and he developed a special sash bar that incorporated both an external gutter to carry away rainwater and internal channels to deal with condensation. Components such as these were ideal for mass production to standard sizes. Combined with the cast-iron columns and standard sheets of glass, they formed the basis of a prefabricated building system.
The “prefab”
In the 1930s a number of architects, including Walter Gropius, designed mass housing made of factory-produced components and assembled on site. A concerted effort to make this type of housing came about in Britain after the Second World War, when a shortage of housing and surplus capacity in factories that had been producing military aircraft were key factors. “Prefabs” were intended to be made in these spare factories and assembled as temporary housing that would last between 10 and 15 years. Several thousand of these mainly aluminum- or asbestos-cement-walled bungalows were built, and they proved popular with residents, who liked their modern fittings and pleasant, light interiors. In many cases these “prefabs” lasted several decades and a few still survive (below).
The Crystal Palace Paxton’s triumph was a design for the building to house London’s 1851 Great Exhibition—the vast, glittering glass structure that became known as the Crystal Palace. Designed at the last minute (Paxton famously did the first sketches on the blotter during a meeting), the Crystal Palace was conceived like one of Paxton’s greenhouses. And as a huge aisled building with many standard repeating elements—sashes, gutters, arches, beams, girders, panes of glass—it was an obvious building to be made by prefabrication.
The use of prefabricated components was vital because the exhibition committee had left very little time for the Crystal Palace to be built. Only by manufacturing the parts off-site and transporting them to Hyde Park as they were needed could the great exhibition building be constructed quickly enough. So Paxton arranged a huge logistic exercise. Wrought-iron beams were manufactured by Fox and Henderson in Birmingham; the same firm supplied wooden components from a mill in Chelsea; two factories in Dudley, in the West Midlands, produced the cast-iron columns; glass came from Chance’s works, also in Birmingham. Dedicated trains brought the components straight to the site and they were fixed into place almost as soon as they arrived. The entire job took just nine months.
System buildings
The term “system building” is used today to describe the way in which either entire buildings or large prefabricated components can be factory-made and delivered complete to the site. Buildings or parts are fully finished at the factory and need only to be connected to services to be usable. Many homes, factories, and schools have been built in this way, especially in the 1960s and 1970s, when system building was popular.
The Crystal Palace represented the triumph of prefabrication. It showed how buildings could be made from standard components in very little time, and without the disruption caused by the building industry’s “wet” trades. It set the trend for the way railway stations, factories and other utilitarian buildings would be produced in the future.
New initiatives There were manufacturers who shared Paxton’s vision poised to seize the opportunities offered by all this publicity. At the same time as Paxton was conceiving his design, Walter Macfarlane, a Glasgow businessman, was preparing his first catalog of prefabricated buildings—structures made mainly of metal that were sold as flat packs and were shipped far and wide, even to outposts of the British empire. From garden sheds to apartment blocks, from corrugated iron churches to industrial warehouses, prefabrication in its different forms has been widely used ever since.
“…these bright, clean, easily maintained houses were very quickly taken into the hearts of their occupants”
Peter Ashley, More London Peculiars (on prefabs)
the condensed idea
Mass production transforms the building process
| timeline |
| 1836 |
Joseph Paxton begins work on the Great Stove, the pioneering greenhouse at Chatsworth, Derbyshire |
| 1850 |
Walter Macfarlane of Glasgow publishes his first catalog of prefabricated buildings |
| 1851 |
Great Exhibition opens at the Crystal Palace, Hyde Park, London |
| 1944 |
British Temporary Housing Programme, with prefabricated bungalows, launched |
