When presented with a design using Prefabricated Prefinished Volumetric Construction (PPVC) solutions, a quantity surveyor requires proven cost information, lead time, operation and maintenance data sets, capable supply chain and installation contractors in order to prepare a cost estimation and lifecycle costings using Building Information Modeling (BIM).
LET’S BREAK THIS DOWN
WHAT IS PPVC?
Prefabricated Prefinished Volumetric Construction is a construction method whereby free-standing units, such as an entire bathroom, are manufactured and assembled in an offsite fabrication facility before being transported whole to the building site for installation. Where the approach differs to previous prefab systems is that, the finishes for the walls, ceilings and floors are all completed in the offsite facility.
For Quantity Surveyors, benefits of employing this method of construction will need to be assessed against three critical factors: time, cost and quality.
The use of PPVC typically requires extensive coordination prior to and during construction. This means there will be a need for additional project planning and design efforts, and an early commitment on the part of the developer/builder.
Increased collaboration between project stakeholders (including the manufacturer) is required during the early design stages phase, and the use of BIM to improve co-ordination and facilitate communication among project stakeholders.
Once onsite, the PPVC modules will require contractors who are highly skilled in the specifics of their installation.
The manufacturer will need to be engaged early in the design phase to ensure manufactured components can be delivered to the site in a timely manner. In addition, the manufacturer will be able to provide a reliable guide as to when the prefab modules will be ready for delivery.
For quantity surveyors, information on the capacity for the manufacturer to provide the PPVC components to meet the construction timetable, transport time from the factory to the building site, and time taken to install the PPVC components, will be important in determining PPVC viability.
“For quantity surveyors, information on the capacity for the manufacturer to provide the PPVC components to meet the construction timetable, transport time from the factory to the building site, and time taken to install the PPVC components, will be important in determining PPVC viability.” Grant Warner, CEO, AIQS.
Currently, the manufacture of PPVC attracts higher initial costs than conventional construction methods.
Studies carried out in Singapore indicate that optimum utilisation of PPVC increases productivity by up to 50%. Consequently, the construction process is speeded up dramatically, construction labour costs are reduced, resulting in tangible cost and time savings. Those benefits are offset slightly by subsequent increases in logistical and transportation costs.
For quantity surveyors, information covering the manufacturer, transport, logistical, installation costs, and timeframes of PPVC components will be integral to determining the extent of utilisation PPVC. Early integration into BIM will help identify whether PPVC is attractive for the development.
Critically, for a quantity surveyor to deliver a quality lifecycle costing analysis to their client, they will need reliable data sets, supplied by the manufacturer, that can be plugged directly into BIM software.
By carrying out a significant portion of work, not just offsite, but in a controlled, factory environment, substantial improvements in quality, safety, as well as a vast reduction in waste, noise pollution and dust at the building site, can be secured.
For quantity surveyors, savings in time and cost are usually reflected in a decrease in quality. However, with PPVC, uniform quality is invariably maintained.
In essence, when everything aligns the incorporation of PPVC can improve workflow continuity, increase efficiencies in the use of resources, minimise construction waste, provide a better quality product, and reduce the number of on-site contractors as well as construction duration.■
Grant Warner – CEO, Australian Institute of Quantity Surveyors (AIQS)