Over the past 30 years, HDB has been striving continuously to innovate and increase site productivity to reduce manpower requirements at its worksites. With the call for greater productivity, HDB’s track record in using the prefabricated method of construction provides a shining example for others to follow.
The HDB Centre of Building Research (CBR) was set up in the mid 1990s to spearhead the promotion of prefabrication technology. Today, more than 70 percent of a typical HDB flat is constructed using the prefabrication method. Some examples of standard prefabricated components are external facade walls, floor slabs, beams, columns, and staircases, to name a few. In comparison, the level of prefabrication is much lower at 8 percent for private housing projects.
HDB was able to achieve this quantum leap mainly because of dedicated efforts in promoting the use of prefabrication technology and raising worker productivity, a recent recommendation from the Economic Strategies Committee (ESC). The need to raise worker productivity was also announced in the 2010 Budget Statement in Parliament, with a focus on increasing work capability and reducing Singapore's reliance on foreign labour.
What’s so great about it?
The key reason for the move towards prefabrication technology in the early years was that it shortened overall construction time, and brought significant cost savings to HDB’s massive building programme. It was also the ideal way to go when HDB implemented the upgrading programme, because it shortened turnaround time, eliminated on-site construction, improved site cleanliness and reduced inconvenience to residents. This was a definite plus point for residents, who need not move out of their homes.
Today, prefabrication technology remains relevant even with buildings soaring skywards. It has been used to construct the recently completed HDB 50-storey residential project, The Pinnacle@Duxton. Despite its height and the varied façade wall designs, HDB was able to achieve a floor cycle time of about six to eight days, instead of the normal ten to twelve days.
When applied to steel reinforcement works, prefabrication technology increases the productivity of HDB’s structural design and detailing by 200 percent, and steel fabrication works three times more. Today, 90 percent of all reinforcements used in public residential projects is prefabricated.
Getting others on board
HDB has played a key role in transforming the construction industry and building a specialised pool of precast concrete components and prefabrication steel suppliers. For every HDB project, HDB provides design guides to appointed consultants and hand-holds those not familiar with the prefabrication construction system to ensure better project outcomes.
Believing that more widespread adoption will benefit the industry and raise innovation and productivity for Singapore, HDB has been zealous about sharing its expertise with other government agencies, the construction industry, tertiary institutions and international visitors.
Key Innovative Products
With its emphasis on standardisation and mechanisation, many aspects of construction work can now be done in a factory environment. This reduces backbreaking work on-site, and an over-reliance on manual labour, while improving quality.
Not content with these measures, HDB continued its Research & Development (R&D) efforts, which yielded some innovative products and enhanced prefabrication solutions over the years. Some of the HDB innovations include:
- SECADD integrated engineering design and drafting software
- HDB spiral connector system
- Prefabricated Ferrolite partition wall system
- Prefabricated Extensive Green (PEG) roof system
This integrated design analysis and drafting software system (SECADD) helps engineers with the design and detailing of prefabricated components. It is the only software developed and customised to align with local application.
The spiral connector is a patented splicing system for connecting reinforcing bars. It can be used for connecting precast components as well as cast in place construction to eliminate the need for lapping in steel bar. The spiral connector is a cheaper alternative to other connectors of equivalent performance in the market. In addition, it can be easily installed and handled by workers safely.
The FerroLite partition wall system was developed to provide a more sustainable and economical solution for internal partition walls. The development of FerroLite reduces the amount of concreting materials required by 30 percent, as compared to other cementitious partition walls, and is more environmentally friendly. Currently, FerroLite is fully implemented in all HDB projects. The system received an endorsement as Singapore Green Label (SGLS) product by the Singapore Environment Council last year.
To enhance environmental sustainability and to reduce the potential heat-island effect, HDB introduced greenery to some concrete roof tops. This green roof system helps to reduce the ambient temperature, providing our residents with a more conducive living environment. HDB has successfully developed its own prefabricated green roof system for use at its estates. The system is cost effective, lightweight, easy to install and requires minimal maintenance.