Once viewed as low-budget and low-quality housing, newer prefab designs can provide urban housing and housing in the bush with quality equal to or better than stick-built homes.
Modular prefab design offer flexibility for numerous common situations, such as temporary housing during a renovation, and long-term housing for victims of natural disasters. Using a low-impact foundation system minimizes site work and site disturbance, and ensures the future portability of the homes.
Dutch company Heijmans began their Heijmans ONE project to address two issues: lack of good quality, affordable housing in urban areas, and useable but derelict urban sites.
To that end, architect Tim van der Grinten of Moodbuilders Architecture designed a small, two-module, steel- and wood-framed home that’s prefabricated in a factory and shipped by truck to the building site. Once on-site, the house can be erected in one day with just a crane.
According to van der Grinten, the home was designed to be “a removable self-contained home offering full independence in all respects with all relevant components.”
The company has produced and installed two prototype homes so far, both in Amsterdam. One home is a test case in which editor Carmen Felix is living for a few months to help refine the design and usability. The other is a demonstration model where interested people can stay for a night. Heijmans aims to build and install 30 units this summer/autumn in urban areas in cities such as Amsterdam, Rotterdam, and Den Bosch.
The design uses a steel and wood frame to enclose a total area of 45 square metres. The lower module houses the kitchen, bathroom, dining area, living area and an exterior terrace, while the upper floor houses the bedroom and a small office space.
The prefab modules are delivered in two trucks. Once on site, they’re stacked on the foundation by crane. Natural wood walls and ceiling, with massive floor-to-ceiling windows, make for a bright interior. The frame system carries the load on the exterior panels, creating an open interior space that can be modified easily in the future. Heijmans estimates the homes will last 25 to 30 years.
“The great thing about Heijmans ONE is that it is a temporary solution whose quality rivals that of permanent housing,” said Heijmans property developer Anneke Timmermans-Dalhuisen.
Cost for the units has not been set, but it is believed they will be eminently affordable.
“For the Netherlands we're working with a targeted rent of 700 to 800 euros/month," said Heijmans communications manager Arjan Hofmann. Private rents should cost 900 to 1000 euros per month, depending on the cost of the land and municipal charges, which rent for social housing in the Netherlands is capped at 699 euros per month.
Standard water, sewer, and electric service can be used, though Heijmans is also planning options for off-grid living, such as integrated solar photovoltaic panels and a water system.
“Most of all, we’ve wanted these homes to inspire a feeling of positivity," said van der Grinten. "High ceilings, space, light, a nice view. This project is a step in a new direction: away from permanent, immoveable properties.”
Prefab Designs Offer Flexibility with High Quality
Architect Matthew Dynon says each module ships via truck in non-oversized dimensions. When on site, a truck-mounted crane unloads the modules onto the foundation system, then departs. Two workers with a pulley system can then complete the fold-out process.
Benefits of this approach, according to Dynon, include better quality control due to factory assembly, flexibility in building design for each site, and limited site impact. He added that the modules are not limited to any particular foundation system, so screw piles, traditional brick piers, or even temporary concrete pads can be used.
In addition, Dynon said the cost is competitive at $1,500 to $2,000 per square metre, which he said “is significantly less than a bespoke site build of similar architectural quality.”
The prefab modules are designed to be used alone or in multiple combinations, providing enhanced adaptability to each site.
“The roof design and parapet walls allow modules to connect, slide, rotate, step, extend and stack,” Dynon said. “Generally speaking, the system allows multiple modules to be added in a multitude of ways to form a vast variety of different house plans that can respond more successfully to the practical requirements of any given site conditions.”
In addition to rainwater harvesting, sustainability features include passive solar design, and high performance insulation in the walls, roof, and floor. According to Dynon, the company is working with the University of New South Wales UNSW to achieve 8 Star energy efficiency ratings. The low-impact foundation system also enables the homes to be removed and reused without demolition.
So far, the company has built a demonstration model, Pavilion House, in Belmore, Sydney, with a budget of $100,000. The house will be open for viewing in March, and provides two bedrooms, a bathroom, and a kitchen in 60 square metres.
With its extreme portability and low need for skilled workers, the MODE design would seem the ideal approach for temporary structures, housing for victims of natural disasters, and the like. Dynon said the company could address that need in the future.
“We consider our system to be an adaptive framework that will mutate in different markets to arrive at real solutions in a given context,” he noted.
However, the system will have to be optimized for each market because, as Dynon said, “a one size fits all approach to low-cost housing has been proven ineffective over the last five decades.”