An early adopter of prefabrication technology, HDB introduced the use of precast components in the construction of flats as far back as the 1960s. Today, HDB uses precast components at an optimal volume of 70% of its residential buildings’ concrete structure.
Precast technology enables building components to be manufactured off-site in a controlled environment before being assembled at the worksite, thereby speeding up construction. This method yields other benefits, such as stricter quality control, decreased construction waste, and improved safety on site.
With technical expertise accumulated over the years, HDB has developed its own precast technology known as the HDB Precast Building System. Comprising a variety of 2D precast components, the building system forms the foundation for deriving game-changing solutions for more integrated and complex 3D precast technology. For example, HDB pioneered the Concrete Prefabricated Bathroom Unit (PBU), which will be implemented in 60% of the dwelling units to be launched in 2017.
Driving these innovative ventures in construction technologies are engineers and architects from HDB’s Building Research Institute, who have been testing mechanised approaches to produce customised components, such as large floor panels. The use of these custom-made precast panels reduces the need for site handling and carpentry works, thus raising construction productivity.
Currently, HDB is working to fine-tune concrete Prefabricated Prefinished Volumetric Construction (PPVC), which was first piloted at a housing project in Bukit Batok. The PPVC involves fabricating 3-dimensional standard prefabricated modules of whole rooms to further reduce work on site. These modular units can be combined in different configurations to create different flat layouts. HDB aspires to implement PPVC progressively, increasing the number of projects using PPVC while building up construction capability and capacity.
Before ramping up the implementation, it is crucial to establish structural and design details and standards. Through the identification and systemisation of methods, design details and processes, standardisation will help improve the ease of construction and building productivity. For instance, the use of a Prototype Unit Plan Guide since 2013 has allowed HDB to design functional floor plans in a shorter time while optimising the designs for precast works. In the case of the PBU, the standardised bathroom unit has enhanced coordination between its corresponding structural, mechanical and architectural works.