Debated in Parliament on 15 Oct 2012.
Ms Sylvia Lim asked the Minister for National Development (a) what due diligence does the Building and Construction Authority (BCA) exercise before granting approval for condominium developers to use tempered glass in panels used as safety barriers at balconies despite the associated risk of spontaneous breakage; (b) what led the BCA to require the use of laminated glass instead in such panels with effect from July 2011; and (c) what is BCA's recommendation to resolve the safety issues for condominium developments which were constructed before application of the July 2011 ruling.
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BCA requires safety barriers at balconies in condominiums to be designed by a Qualified Person who must be a Registered Architect or a Professional Engineer. Among other things, the barriers must be able to withstand the required horizontal loading as specified in our building codes. The latter are based on the British Standards for barriers in buildings.
Prior to July 2011, the BCA allowed tempered glass in panels to be used as safety barriers because tempered glass is known for its strength, and can withstand the horizontal loading and impact. Tempered glass does have a risk of spontaneous shattering which is caused by the expansion of nickel sulphide (Nis) crystals over time in the glass. Spontaneous shattering is, however, rare. That is why its use as safety barriers continues to be allowed in many countries, including USA, UK, Australia and Hong Kong.
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Notwithstanding this, we decided to prescribe the use of laminated glass if glass is used as a safety barrier in our Building Control Regulations from July 2011, so as to enhance the design safety of the barrier. Laminated glass is the bonding of two or more pieces of glass together for greater strength. If one or more of the glass layers break, the laminate will have some residual strength, while the plastic interlayer will hold the broken glass fragments together, preventing them from falling from height. Tempered glass can still be used as glass layers in laminated glass.
Owners of existing buildings who wish to enhance their safety barriers may consider retrofitting and using laminated glass. Alternatively, they may install an additional layer of safety film on the tempered glass which will hold the broken glass shards together in the event of spontaneous shattering.
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