Architecture
The Pros and Cons of Prefabricated Homes
Thinking about a prefabricated home? From quality control to cost and timeliness, here is an architect's take
As the price of labour in Australia has steadily increased, the cost of building quality homes has become increasingly unaffordable. In most modern industries automation has played a big part in reducing the total number of working hours with the intent of keeping a lid on prices, but the housing industry is intrinsically labour-intensive, and on a building site the usefulness of automation is limited. To maintain some level of affordability the building industry has begun exploring new ways of constructing homes that are more efficient and ultimately more cost-effective.
Although not an entirely new concept, the off-site prefabrication of homes is one of the more promising developments to come out of the construction industry in recent times. Prefabricating homes in a factory-type environment has the potential to improve construction time and quality control, reduce the impact of environmental factors and control costs.
Choosing to prefabricate your new home will have a number of advantages and disadvantages and it’s worth considering them before making a decision. I’ve outlined the main ones here…
Although not an entirely new concept, the off-site prefabrication of homes is one of the more promising developments to come out of the construction industry in recent times. Prefabricating homes in a factory-type environment has the potential to improve construction time and quality control, reduce the impact of environmental factors and control costs.
Choosing to prefabricate your new home will have a number of advantages and disadvantages and it’s worth considering them before making a decision. I’ve outlined the main ones here…
Construction time
PRO: Prefabrication offers a significant improvement in construction time. Where a normal build time for a house may take more than a year, a prefabricated home can be completed in just a few months. The time advantages come from many areas, but include having much better equipment on hand and in close proximity to the building site, the ability to build the house in a central industrial location where suppliers are in close proximity, improved worksite lighting and, in the case of manufacturers who have internal workspaces, there are no weather delays. Factory yards are also generally neater and have much better amenities for staff which ultimately helps to improve productivity.
PRO: In covered factories the construction sequence can be modified to improve efficiency. And it will not be important to close up the building before any of the internal work can be completed. In many cases many trades can work simultaneously which greatly improves efficiency.
PRO: There may also be advantages in the approval process as no building permit is necessary until the house is brought to the site. It is possible for construction to begin while the building permit is being processed, but there are risks associated with this as well. Improved construction time is not only more convenient, but also helps reduce carrying costs associated with a protracted building process.
Step inside this home
PRO: Prefabrication offers a significant improvement in construction time. Where a normal build time for a house may take more than a year, a prefabricated home can be completed in just a few months. The time advantages come from many areas, but include having much better equipment on hand and in close proximity to the building site, the ability to build the house in a central industrial location where suppliers are in close proximity, improved worksite lighting and, in the case of manufacturers who have internal workspaces, there are no weather delays. Factory yards are also generally neater and have much better amenities for staff which ultimately helps to improve productivity.
PRO: In covered factories the construction sequence can be modified to improve efficiency. And it will not be important to close up the building before any of the internal work can be completed. In many cases many trades can work simultaneously which greatly improves efficiency.
PRO: There may also be advantages in the approval process as no building permit is necessary until the house is brought to the site. It is possible for construction to begin while the building permit is being processed, but there are risks associated with this as well. Improved construction time is not only more convenient, but also helps reduce carrying costs associated with a protracted building process.
Step inside this home
Construction price
CON: Even though there are numerous improvements in efficiency and cost control associated with prefabrication, the construction price of a prefabricated home will not necessarily be cheaper than conventional construction.
Prefabricated homes need to be transported on the back of a truck. They can be lifted off the truck using simple hydraulic jacks, but if the site is difficult they may need to be craned into position. Depending on the complexity of the transport and lifting job, moving a home may cost anywhere from $5,000 to well over $20,000. This may immediately wipe out the efficiency advantages of prefabrication.
CON: One area often overlooked when comparing prefabrication to conventional construction is the cost of renting the factory floor space to build the home. Factory floor space is expensive and will ultimately add to the cost of the build. Provided the build is efficient and completed in a short period of time this cost may be minimised.
PRO: From a pure cost perspective it is likely that prefabrication will be a little cheaper than conventional construction. And it will provide a quick turnaround and improved construction quality for little, if any additional cost.
CON: Even though there are numerous improvements in efficiency and cost control associated with prefabrication, the construction price of a prefabricated home will not necessarily be cheaper than conventional construction.
Prefabricated homes need to be transported on the back of a truck. They can be lifted off the truck using simple hydraulic jacks, but if the site is difficult they may need to be craned into position. Depending on the complexity of the transport and lifting job, moving a home may cost anywhere from $5,000 to well over $20,000. This may immediately wipe out the efficiency advantages of prefabrication.
CON: One area often overlooked when comparing prefabrication to conventional construction is the cost of renting the factory floor space to build the home. Factory floor space is expensive and will ultimately add to the cost of the build. Provided the build is efficient and completed in a short period of time this cost may be minimised.
PRO: From a pure cost perspective it is likely that prefabrication will be a little cheaper than conventional construction. And it will provide a quick turnaround and improved construction quality for little, if any additional cost.
Quality control
PRO: Quality control is a huge advantage of prefabrication. A factory site can provide high-quality tools that are far superior to those being carried onto a typical worksite. Better tools ultimately result in much smaller tolerances and improved finishes. Improved lighting and dry conditions also ensure that workers have complete control of their work.
PRO: Improved tolerances in construction have obvious aesthetic advantages, but also result in improvements in energy efficiency. By eliminating gaps that allow air ingression, the internal spaces will require less heating and cooling.
PRO: Quality control is a huge advantage of prefabrication. A factory site can provide high-quality tools that are far superior to those being carried onto a typical worksite. Better tools ultimately result in much smaller tolerances and improved finishes. Improved lighting and dry conditions also ensure that workers have complete control of their work.
PRO: Improved tolerances in construction have obvious aesthetic advantages, but also result in improvements in energy efficiency. By eliminating gaps that allow air ingression, the internal spaces will require less heating and cooling.
Trucking sizes
CON: Prefabricated buildings are limited in size by requirements for permissible road widths and heights. These limitations are usually managed by splitting the building into manageable modules that are joined together on-site.
PRO: Careful design will result in a building that suits your needs and isn’t compromised by the restraints of road transport.
CON: Prefabricated buildings are limited in size by requirements for permissible road widths and heights. These limitations are usually managed by splitting the building into manageable modules that are joined together on-site.
PRO: Careful design will result in a building that suits your needs and isn’t compromised by the restraints of road transport.
Cost control
PRO: Because prefabrication occurs in a controlled environment it is easier to estimate the actual cost of construction. Typical builders will make allowances for things that may be unforeseen or unknown. These allowances will be incorporated into their contract price. In prefabrication those allowances may be reduced or eliminated.
PRO: The controlled environment makes the building process more predictable which should limit the risks of variations. Most prefabrication builders will offer fixed-price contracts.
Finance
CON: The ability to arrange finance for prefabricated structures is a significant problem. Most banks will not lend on a building until it is fixed to the site. This usually means that the owner will be required to pay the fabricator in cash until the house is delivered.
PRO: It may be possible to stage the project so that modules can be gradually delivered and fixed to the site, allowing them to be financed and the cash freed to pay for the following unit. But note that this method does negate the advantage of decreased construction time.
LET US KNOW
Have you chosen to build a prefabricated home? How have you found the construction experience? Tell us all about it in the comments section.
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PRO: Because prefabrication occurs in a controlled environment it is easier to estimate the actual cost of construction. Typical builders will make allowances for things that may be unforeseen or unknown. These allowances will be incorporated into their contract price. In prefabrication those allowances may be reduced or eliminated.
PRO: The controlled environment makes the building process more predictable which should limit the risks of variations. Most prefabrication builders will offer fixed-price contracts.
Finance
CON: The ability to arrange finance for prefabricated structures is a significant problem. Most banks will not lend on a building until it is fixed to the site. This usually means that the owner will be required to pay the fabricator in cash until the house is delivered.
PRO: It may be possible to stage the project so that modules can be gradually delivered and fixed to the site, allowing them to be financed and the cash freed to pay for the following unit. But note that this method does negate the advantage of decreased construction time.
LET US KNOW
Have you chosen to build a prefabricated home? How have you found the construction experience? Tell us all about it in the comments section.
MORE
From the Pros: How to Work With an Architect
From the Pros: 8 Design Habits of a Successful Architect
Why New Homes Are Harking Back to the ‘Core House’ Design of the 1950s
The prefabrication of homes has long been a dream of many architects, but it has been the mining industry that has really been responsible for the development of the concept into a fully viable industry. Across our country’s north, entire towns have been constructed from prefabricated units that have been built and trucked from our major cities or assembled overseas. Even entire apartment buildings, with multiple floors, have been constructed from prefabricated units, and as architects become more familiar with prefabrication methods they are increasingly finding prefabrication as an attractive way to build inner-city apartments and high-rise hotels.
As the mining construction boom is slowing down, a number of prefabrication builders are now looking towards the residential market to fill their orders.