prefabrication: why in nz? · mike expects a two-tier system to develop within nz building, with...

Prefabrication: Why in NZ?A window into prefab building construction in New Zealand.

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A window into prefabricated building construction in New Zealand?

Prefab or prefabricated construction refers to any building, or part of a building, that is made away from the final building site. Also referred to as off-site construction, prefab building has a long history in New Zealand. ‘Portable’ colonial cottages shipped in parts from Europe were some of the first permanent homes of European settlers and there is even some evidence that Maori packed wetland Raupo to make wall panels.

Already a popular method of construction in the USA, Sweden and Japan, prefab construction is currently uncommon in New Zealand’s housing market, which instead relies almost entirely on traditional building methods and the production of on-site homes. However as the demand for affordable housing becomes louder and the critical shortage of homes across the country becomes more apparent, the case for robust quick build prefabricated construction is clearer than ever.

Product suppliers and architects in the New Zealand construction sector are also going to have to get out of their comfort zone if they want to be relevant when the new wave of prefabricated construction methods changes the build tide. Altus Windows is certainly trying to challenge the norm and offer clever new ways to offer better windows for better build efficiency.

Prefabrication: Why in New Zealand? 1 | altuswindows.co.nz

The future of

prefabrication

in New Zealand.

New Zealand’s estimated resident population rose from 4.41 million in 2012 to 4.79 million in June 2017, according to Stats NZ. This continued population growth, particularly around urban areas, has put increasing strain on our housing market and resulted in a significant shortage of homes.

As of 2018, NZ has a calculated housing deficit of 71,000 homes according to the Ministry of Business, Innovation and Employment (MBIE), while more locally Auckland and Canterbury are both in need of 15,000 homes each.

The acute need for housing has resulted in reduced building quality and is currently causing a property price bubble which blocks particularly first-time buyers from the market. Demand for houses is also a source of government debate, and the ambitious goal to build 100,000 new homes over the next decade is part of its Kiwibuild program.

New Zealand requires homes that are affordable, of good quality and can be built quickly enough to fill demand - something that the current model is not delivering.

2 | altuswindows.co.nzPrefabrication: Why in New Zealand?

3 | altuswindows.co.nz

Advantages of prefab Prefabricated building offers an efficient, high quality solution to a housing shortage that is only getting worse. Prefab housing has several key advantages over traditional hammer and nail building:

• Faster time frames: The key to prefab construction is speedy delivery. Off-site construction can reduce overall building time by 60 per cent and a prefab structure can typically be watertight on-site within four to five days.

• ●Transparent, lower costs: Prefab techniques have several cost benefits. Notably this form of delivery can save around 15 per cent on total construction costs. This is potentially $25,000 removed from a typical project budget according to Prefab NZ’s value case for Prefab. Prefab’s highly accurate and digitally driven construction techniques also mean that cost is a known quantity at the beginning of the process, rather than an estimate that could run over budget.

• ●Quality: Currently 91 per cent of NZ houses have defects. Carefully planned and expertly created factory prefab homes have much lower risk of faults.

• ●Sustainability/waste reduction: By utilising high tech factory equipment, construction waste can be dramatically reduced. For example, EasyBuild’s prefabrication process produces a total of half a skip of waste, compared to the three or more skip-fulls that standard construction produces.

• ●Productivity: Estimates are that prefab construction will increase industry productivity by up to 2.5 per cent according to Prefab NZ.

• ●Health and safety: Construction takes place in pieces in a risk-assessed factory environment, reducing the risk of injury for workers.

Challenges of prefabThere are however some challenges that prefab construction will have to face if it is to make an impact in the New Zealand market:

• ●Misconceptions: The word prefab still tends to conjure up images of poor quality 70s classrooms - cheap and nasty. Prefab will have to change the market preference for on-site traditional building. Architects and designers can help lead in this space by creating adaptable designs with performance, aesthetics and the off-site construction environment in mind.

• ●Bank loans: Due largely to the recent nature of prefab houses in NZ, there can be some challenges regarding home loans under current banking practices. There is presently no standardised bank lending approach for homes constructed off-site. There is a tendency for lenders to only offer to provide money when a structure is erected on-site, which in prefab construction is very near the end of the process. This makes financing challenging. However the governments hunger for getting prefab construction into the market may see lending rules and building regulations change to remove barriers that inhibit easy uptake.

• ●Regulations: Again, the fairly recent nature of prefab construction means that there is some catching up to do for building regulations. This restricts the sites that can currently be approved for prefab construction.

Prefabrication: Why in New Zealand?

The next steps

for prefabrication

in New Zealand.

The current uptake of prefab in New Zealand is low. Traditional preference for on-site construction means that prefab solutions are currently only used for 11 per cent of building components for non-residential buildings and 37 per cent for new homes, according to Prefab NZ’s value case report. But with the current housing need, what is the next step for prefab in the NZ building industry?

“It will just become another tool that builders don’t think about” says Pamela Bell, CEO of Prefab NZ. “Just like pre-nailed roof frames and wall trusses that come to site, builders will be ordering their wall panels fully furnished.”

Pamela expects that in the near future construction workers will become accustomed to working with an enclosed and watertight prefab structure almost from the outset. Mike Fox, director of EasyBuild Ltd., had a similar outlook. “It’s going to become part of the norm. It’s been slow to take off, but now that we have real solutions that show the price difference and the benefits of what you can get, the shift will happen.”

Mike expects a two-tier system to develop within NZ building, with buyers opting for either traditional bespoke build houses or prefab models. He expects this choice to become standard within the next five years.

“We cannot afford to carry on building the way we are.” - Mike Fox



Methods of prefabricated construction While prefab is in some ways a very standardised process, there a number of construction methods to choose from:

Component based: Small parts of what will make up the whole building are constructed off-site and fitted together on-site. Components could be staircases, parts of the roofing structure or flooring.

Panelised: A form of two-dimensional construction where a house is split into panels that are constructed off-site and fitted together on-site. Panels can be walls, floors and ceilings.

Volumetric: Three-dimensional volumes or modules that equate to rooms are built off-site.

Hybrid: A mix of several systems, usually volumetric and panelised.

Complete buildings: The whole building is completed on the factory floor then transported and installed on-site.



The EasyBuild volumetric/modular solution EasyBuild has orientated its construction method around the work of Dennis Ryan, who developed the first modular-style NZ homes in the early 1980s. Ryan’s ideas were devised from researching Sweden’s prefab techniques and then adapting processes to New Zealand’s unique conditions. Over the last three years, EasyBuild has focused on modernising and refreshing Ryan’s developments and bringing volumetric prefab homes back to the market. EasyBuild sees the re-launch of the modular construction concept as a necessary response to the new demand for affordable high quality homes.

EasyBuild opts for a timber portal and panel system. The structure of the house is created using timber portals before being filled with pre-assembled panels. Timber was chosen as the main material because it is a natural product that the company can source locally (within 30 kilometres of the factory). This means that transport costs are kept at a minimum, helping both the client and the environment, while also supporting local industry. EasyBuild’s method has several key benefits:

• Simplicity and speed: The modular system is incredibly simple and allows for fast construction speed. EasyBuild can currently produce an average sized home in a day and can up production to twice that if needed. Once on-site with foundations in place, the structure itself can be watertight in four to five days and fully completed in just six to nine weeks.

• Strength: EasyBuild’s construction method creates robust homes. The interior lining is impact resistant - perfect for rental or social housing or just low maintenace living. External walls have two skins and a drain cavity to prevent leaking. This external protection means that the buildings will not degrade at all over 20-30 years.

• Quality: EasyBuild’s strictly controlled factory environment creates homes with an air leak of only 3 ACPH (air changes per hour) compared to 7-10 in conventional homes, allowing greater heating and cooling efficiency. Also as described earlier EasyBuild’s homes are specifically designed for NZ weather conditions.

• Internal volume: This modular/volumetric technique does not require any supporting internal walls, so the internal space available is large compared to total structure size.

• Transportable: The structure is easily transportable and can be positioned anywhere with a foundation. They can also be moved post-construction.

In the face of all these benefits there is one key drawback: modular construction is designed towards a price point rather than bespoke design. EasyBuild customers are able to pick their home from a selection of pre-designed models but are unable to request specifics. While the modular/volumetric construction model is capable of tailoring homes to individual designs, it is more challenging and time consuming, and as such many firms prefer to offer a selection of standard designs.


The Concision panelised solution Concision prefabrication manufacturers follow the panelised method of prefab construction, producing fully enclosed wall, floor and roof panels in its specialised factory.

Unlike a standardised modular product, Concision’s panelised solution is bespoke to the client. Fully utilising digitally driven manufacturing processes, Concision uses a Cadwork software package to translate specific plans into digital files, which are read and manufactured by CNC machinery. This automated machinery works to an accuracy of +/- 0.5 mm, creating less waste and a highly efficient overall process. All panels are fitted with full insulation, cladding, windows and doors, electrics and plumbing within the factory.

Concision opted for the panel construction model because they felt this method aligned best with NZ’s variable conditions while also allowing close control over speed, quality and cost. Concision’s process has several key benefits:

• Speed: Fully fitted factory-made panels can be assembled very quickly once on-site. Concision constructs the whole building in eight to ten hours and can make the structure watertight within a day.

• Efficiency: Off-site production means that the building site can be prepared at the same time as actual building, cutting the construction timeline in half. Concision’s fully formed panels containing electrics, plumbing and windows meaning that once assembled the building is totally complete.

• Adaptability: The panelised method gives Concision the ability to adapt to the requirements of each individual project. Panels can be fitted into single storey residential houses (of which Concision has manufactured around 400), or commercial projects such as schools, accommodation blocks or specialist retirement villages.

• Precision: Concision’s specialist factory houses the latest automated machinery, which guarantees pinpoint accuracy in construction.

That said, the panelised construction model is somewhat vulnerable to weather conditions and it is critical that a building is made watertight as quickly as possible. Fully insulated, plumbed and electrically fitted panels can be damaged if caught in adverse weather conditions during the on-site assembly process.

The panelised model is where architects and designers will have a little more flexiblity in achieving the aesthetic they desire all while knowing build and material costs up front.


How do

windows fit into

the process?

Simply put, the faster windows can be fitted the better. In an industry that strives for efficiency, reducing installation time is a huge bonus. With this in mind, EasyBuild uses the Smartfit® Window System by Altus Windows for its process. “They are perfect for our model,” says Mike Fox. “We can install a Smartfit window in 15 minutes… the time saving is huge.”

Smartfit® Windows have built-in support bars, head flashings, and a face fixing fin meaning once they are screwed in and taped, no more work is needed.

Tony Whale, general manager at Concision, says that while window type was down to the client, his team often used Altus’ Smartfit® design. “We use both traditional and Smartfit windows, but our preference from a manufacturing perspective is the Smartfit window because it’s a lot easier, quicker and less complicated to install.”

But traditional window types can work just as well. Keith Hay Homes are providers of a volumetric prefab solution, but in contrast to EasyBuild’s method the whole structure is completed in their factory and then transported to the site. Matthew Hay from Keith Hay Homes explains that for their process they use the Altus WeatherTight™ Suite. “It’s a proven product, a good all-round suite that’s easy to use.”

Matthew also noted that the Altus Windows Nulook team and the consistency of their product delivery played an important role in Keith Hay’s decision to use WeatherTight™ for their prefab solution. “We have always found them very good to work with and they have made things easy. Knowing what you are going to get and then having the local support is important to us.”

As providers of light, ventilation, insulation and comfort, windows are an essential component of the home. It is crucial that they are watertight, fit perfectly, and compliment the building process.

Which window types work best with prefabricated manufacturing?



ChooseAltus today.

0800 397 263 [email protected]

Both EasyBuild and Concision noted that there was one definite way that their windows could be improved. “In Europe they are working towards the thermally broken, highly energy efficient windows,” says Tony, a window type that is still not widespread in NZ.

Though many aluminium window providers offer a thermally broken solution like Altus’ AllSeasons or Pacific Thermal Suite, its uptake tends to be client or location specific, for example; central Otago and the South Island in general specify it more, largely due to how cold it gets and the payback associated.

With joinery being such a price competitive commodity, for the thermal uptake to increase, it is going to either have to be a building code change towards increased thermal frame performance or really clever window design – Altus Windows is excited by the latter of these two as it forces some truly innovative thinking towards product design right through to delivery.

If you’re looking to understand more about how windows could compliment your building methods, get in contact with the experts at Altus Windows.

Are there ways windows can be improved for prefabricated construction?


prefabrication: why in nz? · mike expects a two-tier system to develop within nz building, with...

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