There are many factors to consider when deciding on a prefabrication build or a site build. Here are six of them.First one being the site location. The construction costs usually increase the further the site is from a capital city; the cost change is known as regional indices. This can be attributed to the increased cost of materials delivery and often a local shortage of skilled labour. For example to build a home in Broken Hill, NSW, it will cost 141% of the cost to build the same home in Sydney, Australia. Prefabricated construction can reduce this cost increase, however, the delivery of the building sections is expensive and must also be considered. Depending on the size of the sections, delivery charges can be substantial, with the requirement of pilot vehicles, police escorts, and special permits, etc. Keeping the width of the building sections to less than 3.5 metres reduces delivery charges substantially as pilot vehicles and police escorts are not required. Unfortunately 3.5 metre wide houses are impractical to live in. MODE’s fold-pack technology manages to reduce transport costs by up to 80% and achieve 8m wide plans. And as they are built in the factory, are not affected by regional indices.
Project Type & Size
Is your project a large duplex, a substantial family home, a humble weekender or a small granny flat? As a general rule the bigger your project is, the better value you will get from a site build, as the builder’s costs to get established on site are absorbed into every square metre. Spec. builders rely on the economies of scale of large houses that are built in close proximity to other houses that are being built by the builder. A small 60m2 addition will usually attract a much higher price per square metre if built on site. If a bespoke site specific design is desired, more consideration is required by the builder, therefore, increasing the price significantly.
With a prefabricated solution costs will tend to remain similar per square metre, whether the home is 40m2 or 350m2 due to the economies of scale coming from producing all homes in the same place or factory.Site Access and Site Slope
The feasibility of placing prefabricated modules in position needs to be considered. Prefab modules are large and heavy. Power lines on the side of the road and existing structures on site, can make craning a prefab module into position,difficult. A clear space of around 4m beside existing buildings is required to get a MODE module past on a truck.
A steep sloping site with difficult access, may make for an expensive site build, as the movement of tradespersons’ and of materials on site, is slow and cumbersome. If a crane can access the site, or crane onto it, a prefabricated build will be alot simpler and easier once the foundations are in place.
Materials and workmanship
Prefab homes are usually constructed of lighter weight materials due to the feasibility of transport and lifting. If you are looking for a masonry home a site build might be more appropriate. Factory construction has less variables and risks than site construction. Rainy days do not need to be considered. Working at heights is not required and the number of decisions that need to be made by a tradesperson are reduced. All these factors make factory production more predictable, more consistent, and more accurate than site construction. It’s a lot easier to produce a quality outcome from a factory build.Preferred shape, form + style
Pre fab homes are usually designed with transport regulations in mind. This has an effect on the form and the shape of the homes. A site build home is not restricted by any parameters apart from cost and build ability. Therefore there is more potential for difference and creativity in a site build. With this potential for difference and creativity comes the requirement for a larger consultant team to resolve design solutions. This adds significantly to the project cost. In most cases a prefab home is designed using a system that utilises standard tested plans and/or details. Each detail does not need to be reconsidered every time.
MODE homesTM has developed their ‘Bespoke Modular’ system to allow almost total flexibility of planning and the ability to choose materials and add ons to arrive at personalised architectural solutions without the additional cost and complication of a consultant team to resolve every construction detail.Time and convenience
A site build project is built on site and therefore requires occupation of the site for an extended period of time. This means that the site is not available for any other purpose such as living in, renting out. This can add significant cost or inconvenience to the project.
As prefab homes are built in the factory, the site can be occupied for the majority of the construction process. This enables life to go on without disruption and avoids loss of rental income.
For a site build the duration of the build can be protracted by unpredictable factors such as bad weather, these do not impact factory construction. Therefore the construction time is more predictable for prefabricated homes.