Prefabrication: New Zealand manufacturers of prefabricated buildings and components 2017

Milad Moradibistouni Victoria University of Wellington, Wellington, New Zealand [email protected]
Brenda Vale Victoria University of Wellington, Wellington, New Zealand [email protected]
Nigel Isaacs Victoria University of Wellington, Wellington, New Zealand [email protected]
Abstract: The New Zealand population is growing fast. In 2017 it was 4,776,500 and has a 90% probability of increasing to 5.30–7.88 million by 2068. This raises the need for more houses that can be built easily, cheaply and fast and be aligned with the contemporary needs of the growing population. This paper focuses on prefabrication as a method of construction that can help the New Zealand housing industry to meet this growing need for more houses. This paper is part of a larger study investigating the use of prefabricated Accessory Dwelling Units (ADUs) as a potential solution to the shortage of housing in New Zealand. This paper reviews 182 manufacturers of prefabricated buildings and components throughout New Zealand to achieve a better understanding of the services they offer, product innovations, and limitations. All data is culled from manufacturers’ websites. An initial analysis reveals that prefabrication in New Zealand is currently focussed on components such as trusses and panels and not on whole buildings. The paper ends by considering what needs to happen if existing manufacturers involved in prefabrication have a role to play in meeting New Zealand’s housing needs.
Keywords: Prefabrication; New Zealand population; housing shortage.
1. INTRODUCTION
The New Zealand (NZ) population has increased significantly over the past fifty years and this trend is predicted to continue at least through the second half of this century. The population of approximately 4.8 million in 2017 is predicted to reach to 6.0 million by 2043, with 75% living in urban areas (MacPherson, 2016). As a result of this population growth, New Zealand is currently facing a shortage of 71,000 houses, increasing by 40 houses a day (Miller, 2017).
Given the urgent need for more houses, it is important to uses the most efficient construction methods and housing types. This paper is concerned with the use of off-site site construction, but it is recognized that other approach could also play a role in providing additional housing e.g. increase densification through the use of high-rise buildings instead of single- story houses. If prefabrication is to play a greater role, then what prefabrication resources are currently available? This paper explores the current state of the prefabrication industry in New Zealand.
This paper firstly defines prefabrication and briefly compares it to traditional methods of construction. It is worth noting that in 2013, 32% of new NZ houses incorporated some form of prefabrication (Moradibistouni and Gjerde, 2017). The paper then investigates the current status of manufacturers of prefabrication in different regions of New Zealand. The aim is to gain a better understanding of the current industry situation and opportunities for future investment and research.
2. PREFABRICATION
Prefabrication is a method of construction where the elements of a building, ranging in scale from a component to a complete building, are manufactured at some distance from the final location. These elements are then purchased and carried to the final location where they are assembled and normally attached to pre-prepared foundations (Seratts, 2012, p. i). The history of prefabricated systems dates back to beginning of nomadic life. Ancient peoples who had to migrate, due to environmental conditions or external threats, needed houses that were easy, fast and cheap to assemble, disassemble and transport (Herbers, 2006, p. 14). Despite this early history and later milestones of prefabrication such as the first iron-framed house built in England in 1830, the idea of manufacturing a house in a factory was only truly realised after WWII (Herbers, 2006, p. 14; Vale, 1995). In New Zealand, the first prefabricated house, pre-made in a builder’s yard, was imported in 1806 as a gift for Te Pahi, the Maori chief. By 1833 prefabricated house kit sets individuals were being imported into New Zealand (Vale, 2002).
P. Rajagopalan and M.M Andamon (eds.), Engaging Architectural Science: Meeting the Challenges of Higher Density: 52nd International Conference of the Architectural Science Association 2018, pp.137–144. ©2018, The Architectural Science Association and RMIT University, Australia.
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Figure 1: Different types of prefabrication. (Source: Moradibistouni and Gjerde, 2017)
Prefabrication methods can be classified in different ways. In this paper, the five categories of component, panel, module, hybrid and complete building used (Figure 1) are based on Bell (2009).
Given the construction industry is the fifth largest industry in New Zealand, the benefits of prefabrication could help the country meet the urgent need for more houses and respond to environmental and energy-related concerns (Moradibistouni and Gjerde, 2017). Table 1 summarizes the potential advantages of prefabrication in comparison with traditional building methods.
Table 1 shows that prefabrication can potentially be faster, cleaner, and have fewer defects and unexpected accidents, while also using energy and water more efficiently. However, the industry could need more financial support to deal with the high capital cost of establishing factories. There may also be barriers for home owners to overcome, as there is an idea that prefabricated houses are temporary, low-quality buildings (Vale, 1995). The industry also needs appropriate Government support to ease the processes of manufacture, sales, transport, and final assembly or installation (Moradibistouni and Gjerde, 2017).
As a first step, it seems important to study existing prefabrication manufacturers in order to understand their abilities and limitations. This could help the industry and government to see what they have and what they need for the future in order to achieve prefabrications’ true potential.
Table 1: Advantages of prefabrication
Advantages % Benefit Source
More energy efficient  50-55% Britto, 2008, p.14; Bell, 2012, p.16 
Less construction waste  40-90% Same as above
More water efficient  30-50% Britto, 2008, pp.14; Phillipson, 2001, pp.3 
Reduction in use of raw material  40-50% Phillipson, 2001, p.3; Gorgolewski, 2005, pp.125-126 
Reduction of defects on completion  60% Same as above
Growth in performance of materials and labour  50% Same as above
Reduction in the energy consumption  50% Phillipson, 2001, p.3 
Reduction in construction costs  15-30% Phillipson, 2001, p.3; Britto, 2008, pp.14 
Reduction in construction time  35-57% Same as above
Fewer total number of man-hours required 40% Stephen, 2012, p.16 
3. METHODOLOGY
In order to better understand prefabrication manufacture data on 182 manufacturers of different types of domestic scale prefabrication has been collected through a web-based search of manufacturers. The main source of names of companies involved in this sector was Prefab NZ (2018) a non-profit membership organization that informs, educates and advocates for innovation and excellence in offsite design and construction in New Zealand. From the Prefab NZ database, a list of 85 manufacturers of prefabricated buildings was compiled. A further 72 manufacturers of frames and trusses were taken from the Frame and Truss Manufacturers’ Association of New Zealand (FTAM NZ) (2016). Twenty-five other companies emerged as a result of a web-based search using keywords related to prefabrication. At the end of this process, 102 companies out of the 182 were selected based on relevance of their services to manufacturing a prefabricated domestic scale building. This list was later shortened to 51 companies that had the most conformity with the goals of the larger study,
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which is establishing whether there is a role for the prefabrication of Accessory Dwelling Units (ADUs) to provide affordable and livable houses for New Zealanders. ADUs are secondary residential unit providing the basic needs of dwellers, with no dependency to the primary unit (Smith, 2017). This process removed companies that did not have the specified criteria needed for the research, as explained below.
• Include only companies directly manufacturing or building one or more types of prefabrication. This excluded companies who simply cut or shape elements (such as timber or steel) without factory assembly or those on-site builders with the ability of constructing a prefabricated home.
• Exclude companies who produce general products for prefabricated buildings, as well as other type of buildings, or those who produce machines or software for prefabricated manufacturers.
• Kitchen category only includes those companies who manufacture whole or some part of a kitchen (e.g. a sink fitted into a cabinet) and send to site it as a module.
• Bathroom category only includes manufacturers that assemble the whole bathroom at their factory and send it to site as a module.
After filtering manufacturers of prefabrication elements, the 51 which had the most conformity stayed in the list. Apart from type of prefabrication, there are various factors, such as additional services and guarantees, types of standard, and the level of flexibility offered to their customers that need to be investigated to gain a better understanding of manufacturers of prefabrication in New Zealand. Despite the importance of all these factors, in this paper only two factors (type of service and location of factories throughout New Zealand) are investigated due to their importance. The larger study, which is currently underway, will investigate all these factors.
These were then classified into eight categories: component; panel; module; container; completed building; kitchen; bathroom; and other, based on the type of services provided for clients. Company websites in each category were then searched for information about installation services, construction materials, whether products are for the do-it-yourself (d-i-y) market, and the adherence to standards and codes. The search also looked for any guarantee and design services offered to customers, the flexibility of each company’s services and any limitations, such as service.
4. ANALYSIS
The results of this survey include a numerical analysis of the number of manufacturers of the different types of prefabrication, their dispersion over the country and the quality of the websites.
4.1 Number of manufacturers offering each type of prefabrication in New Zealand
Based on this data, Figure 2 illustrates the type of services provided by manufacturers and the number of factories that are able to produce each type.
Figure 2: Percentage of total and number of manufacturers producing each prefabrication type
Figure 2 shows that the largest number of these factories (22) are specialists in component-based prefabrication – these are mostly truss- and frame- manufacturers. The next most common type of prefabrication is the panelised system (12 manufacturers), and together these two types make up 64% of all manufacturers. Those who manufacture complete houses
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and bathrooms are the next most common (4 each). There are three manufacturers respectively of modules, containers, and kitchens, with one additional company that provides modular prefabricated wiring systems.
The majority (64%) of manufacturers deal in the type of system (components and panels) with the lowest degree of prefabrication. Only four (8%) manufacturers offer the highest degree of prefabrication, completed buildings.
Components and panelised constructions still have considerable benefits in comparison with on-site methods. However, when it comes to comparing them with other types of prefabrication such as modular construction or hybrid systems, they need more work on-site, which means more time on site and the increased possibility of defects in the final building. As a general point, a higher degree of prefabrication means less on-site time, higher quality, but requires greater care during transportation and assembly to avoid breakages and damage (Khatavkar, 2015; Steinhardt, 2013; Patel, 2015). However, it should be noted that more work on factory is needed for higher degree of prefabrication.
4.2 Dispersion of prefabrication manufacturers in New Zealand
Where the manufacturers of prefabrication houses are located in New Zealand is important as transportation limits are critical when it comes to expansion of this sector (Rippon, 2011). Prefabricated elements can be very vulnerable to defects caused during transportation. Moreover, transport limitations potentially affect design in terms of the maximum weight and dimensions of buildings or building elements (Lu, 2007; Javanifard, 2013).
Based on New Zealand road rules, the heaviest load that can be carried without applying for oversized load approval is 45,000-50,000 kg, Based on the number of trailer axles, the maximum width, height and length of the load can be respectively 2.5-2.55m wide, 4.25-4.30m high and 20m long (Stockdale, 2016; Petterson, 2016; NZ Road Transport Forum, 2018; NZ Transport Agency, 2017 (a), (b), (c)). This means is that the further the site is from the factory the more complicated moving the load becomes, especially in a country consisting of three islands connected by ferries.
New Zealand can be divided to 16 regions, which can be combined into the 2 bigger groups of North and South Islands (Stewart Island, the third island, lies to the south of the South Island). In 2017, approximately 3.7 million people lived in the North Island, (77% of the total population), compared to 1.8 million (23%) living in the South Island (Statistic NZ, 2017 (b)). Table 2 shows number of households in 2013 and 2018 and a projection for 2038 for each region Statistics NZ, 2015), as well as the presence of prefabrication manufacturers identified in this paper.
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Table 2 shows that in 2018 the Auckland region has highest number of households (31% of total), followed by the Canterbury region with 17%, and Waikato and Wellington regions each having 10% of all households. Table 2 also shows the Auckland, Canterbury and Waikato regions will have the highest predicted average growth in number of households from 2013 to 2038, this being by 1.7%, 1.1% and 1% respectively, compared with the average predicted annual growth of 1.1% for all New Zealand. Moreover, the table shows that 6 regions out of 16 have no factory producing any type of prefabricated building or building component. Based on Table 2, the need for houses in the Auckland, Canterbury, Waikato, and Wellington regions in higher than for the other regions.
Table 2: Households and prefabrication manufacturers in the regions of New Zealand
Regional Council area
Households percent
2013 2018 2038 2018 Count (‘000)
Average Annual (percent)
Bay of Plenty 109.1 115.4 133.7 7 24.6 0.8 √
Gisborne 17.5 18.1 19.4 1 1.9 0.4 √
Hawke’s Bay 61.4 64.2 68.6 4 7.2 0.4 √
Taranaki 45.7 48.4 54.3 3 8.6 0.7 √
Manawatu-Wanganui 92.4 95.4 100.3 5 7.9 0.3 √
Wellington 185.4 195.8 220 10 34.6 0.7 √
North Island 1,235.5 1,338.3 1,630.8 75 395.3 1.1
Tasman 19.3 20.6 23.3 1 4 0.8 √
Nelson 19.8 21.3 24.3 1 4.5 0.8 √
Marlborough 18.6 19.3 20.6 1 2 0.4 √
West Coast 14 14.6 15.3 1 1.2 0.3 √
Canterbury 218.2 239.4 288 13 69.9 1.1 √
Otago 83.3 87.8 98.8 6 15.5 0.7 √
Southland 39.4 41 42.7 2 3.3 0.3 √
South Island 412.7 444.1 513 25 100.3 0.9
New Zealand 1,648.5 1,782.7 2,144 100 495.6 1.1 51 100
Source: Statistics NZ, 2015
Table 3 shows the number of manufacturers based on type of prefabrication in each region.
Table 3: Number of manufacturers and type of prefabrication in each region
Region Number of manufacturers producing each type of prefabrication
Comp -onent
Kitchen Bathroom Other Sum
Northland 1 2 3
Waikato 1 1 1 3
Bay of Plenty 2 1 3
Taranaki 1 1 2
Manawatu-Wanganui 1 1 2
Marlborough 1 1
Otago 2 2
Sum 22 12 3 2 4 3 4 1 51
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Table 3 and Figure 3 shows the Auckland and Canterbury regions each have 13 factories undertaking prefabrication, 26% of all factories in New Zealand, which is more than any other region. Wellington region has 9 manufacturers (18% of total). The Waikato region, which based on Table 2 will need more houses than any other region except Auckland and Canterbury, has only 3 factories or 6% of total, same as in the Northland and Bay of Plenty regions. Considering the type of prefabrication each factory can produce, those in the Auckland and Canterbury region can offer six options to their customers, which is more than any other region. On the other hand, the only manufacturer in the Marlborough region produces panels while both manufacturers in the Otago region produce modular bathrooms.
Table 3 also shows there is no manufacturer of complete prefabricated building in both the Wellington and Waikato regions. This is important due the fact that completed prefabricated buildings are bigger than any of the other prefabrication types and harder to transport from another region.
It also needs to be mentioned that each type of prefabrication has its own benefits and potential weaknesses, and suitability for different situations. For example, if the site is hard to access, components or panel based prefabrication may be the best option. However, if the site is easily accessible and the priority is spending less time on the site, a higher degree of prefabrication may be the best.
Generally speaking, it can be said that prefabrication delivers higher quality and efficiency in comparison with on-
site construction methods. Most of this quality and efficiency come from having more control over construction process in the factory. So, comparing types of prefabrication, it can be said that more work done in the factory (higher degree of prefabrication) is equal to higher overall efficiency in comparison with lower degrees of prefabrication (Moradibistouni and Gjerde, 2017).
4.3 Website review
The online web-based search also discovered some points which may affect the willingness of potential customers to pursue the prefabrication route. Notable website issues included:
• Most company website are not straightforward when it comes to communicating with customers. Technical terms are often used without clear explanation. For example, some of these companies stated they could provide prefabricated buildings, but they did not discuss the type of prefabrication on the home page. This could cause customers to check all the links on the websites to understand what exactly will be provided by the company, and the time to do this could deter people.
• Some company websites are very concise, lacking basic and critical information.
• The terms used by manufacturers are not consistent. Some use different terms for a specific type of prefabrication. This is a critical point as each type of prefabrication has its own benefits and disadvantages and is often best used for a specific situation.
5. DISCUSSION AND CONCLUSION
Population and energy demand in New Zealand is growing fast and this will require the nation to face some major issues, including shortages of energy sources and household accommodation. The idea behind this paper was to consider some of the uses of using prefabrication to overcome these issues. This is due the fact that prefabrication method is more efficient in terms of time, safety, use of sources of water and energy while it is safer with fewer defects in comparison with traditional methods of construction.
Figure 3: Manufacturers and type of prefabrication in each region
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This paper is part of a larger study which is investigating the use of prefabricated ADUs as a potential solution to the shortage of housing in New Zealand due their efficiency in terms of resource use and benefits. The larger study investigates all manufacturers’ specifications, including additional services and guarantees, type of standards and other rules they comply with, and the degree of flexibility they give to their consumers through an online web-based search.
This paper focuses on two important factors – the number of manufacturers of the different types of prefabrication and dispersion of manufacturers throughout the country.
Considering number of manufacturers in each group, the majority (64%) produce components or panels. Products of these factories made the on-site construction process faster and more efficient in comparison with traditional methods. However, to overcome the current shortage of houses will need higher rates of production – achievable through factories producing houses with higher degree of prefabrication such as modular, hybrid…