OPTIMISING OFFSITE FOR MULTI-RES

The use of prefabricated construction is gaining momentum as we look for greater savings in both cost, time and quality; recently, a number of multi-storey residential developments have employed either prefabricated bathrooms or prefabricated units to achieve better programme delivery times. With this comes decreased time on site for cranes, structural foremen and finishes foreman, which significantly reduces the preliminaries component of the building cost.

Another potential saving of time related preliminary costs is, time lost to rain and other unfavourable weather conditions. Offsite construction significantly reduces this risk.

A key component of time saving gets delivered to the developer. In some cases a two month faster delivery period compared to an in situ construction method is achieved. This means earlier settlement periods, less interest on any funding components and a higher profit margin to the developer, making this type of construction highly desirable to a developer.

“A key component of time saving gets delivered to the developer. In some cases a two month faster delivery period compared to an in situ construction method is achieved. This means earlier settlement periods, less interest on any funding components and a higher profit margin to the developer, making this type of construction highly desirable to a developer.” AIQS CEO Grant Warner.

Meanwhile another area of savings for the builder lies in quality control and defect control. Traditionally, the main contractor employs someone to walk through the apartment / hotel on a number of occasions, picking up defects. With modular construction the majority of this takes place under the controlled conditions of a factory, with only minor defecting done on site. Again this saves time and money.

With modularity also comes greater overall safety and site security, and reductions in OH&S incidents and injuries which come with the use of small tools will also reduce the builder overheads.

Wastage of materials from off cuts, as well as damage to materials from deterioration or moisture are significantly reduced. Generally an allowance of 5% of all materials is considered reasonable for wastage on site and when you consider approximately 45% of the total construction cost is in materials, this is not an insignificant amount.

Of course the modular / prefabrication system does not work for all cases. Recently there have been examples where the form of the building does not predicate itself to economies of scale to deliver the savings above. If the repetition of floors and the layout of floors are not consistent, then any savings with a modular system are quickly eroded.

Overall the savings that can be made by modular construction on the right project are quite significant and worth investigating on all projects.■