When it comes to building design, glass is a much used and pleasing architectural feature. It looks great and creates a strong solid barrier which doesn’t impair the view or cut out light. As technology in glass has improved, so have the safety features it can offer and it is a regular feature in balconies and balustrades.
It is not without its challenges, however. The biggest risk comes from glass being used without fully understanding it and what is necessary when using it at height.
One of the key features of the Construction Design and Management (CDM) Regulations 2015 is the clarity given over responsibility for use and, inevitably, any incident that might happen in the future to any and every feature of a building. That means that the decision made in the interests of aesthetics and cost must also factor in safety and anticipate any incident.
This consideration starts as with everything else, with design.
Designing for glass in high-rise buildings
When including glass in a design, anything intended for use at height (e.g. in balconies) needs to be examined far more vigorously than when intended for use at ground level.
The first principle is, if glass breaks, it should not be able to fall. With monolithic glass, if a panel smashes, shards can fall from the balcony. With laminate glass, the lamination holds the shards to the adjacent panel (as looked for under the CDM requirements.) It also ensures that, if a panel does smash, the integrity of the barrier is maintained rather than leaving a gap. This benefit was realised by the BSI in 2011 who revised BS EN 6180 to allow using laminated toughened glass without a structural handrail.
Anticipate any and every scenario
When designing a balcony, considering the reputation glass has for being low maintenance, offering a solid barrier and looking good isn’t enough. It also means considering anything and everything which might happen to that glass during its lifetime.
There was a recent incident in a residential high rise where a monolithic toughened glass balustrade was used in a rooftop garden. It was tough enough to provide a safe barrier under normal conditions (and has been used for over 20 years and passes most safety standards). It wasn’t tough enough to withstand an impromptu game of ‘kickabout’ played by resident’s children with the loose stones used as part of the garden design. A kicked stone broke the glass and it shattered, showering the ground below. Fortunately, no one was injured but this is one of those cases where no one had anticipated the risk of the glass breaking or foreseen the possibility of the stones being used for anything other than decoration.
When considering a high-rise residence and the glass in a balustrade or balcony, one has to consider more than the standard uses. It has to perform under extreme circumstances.
“[consider] anything and everything which might happen to that glass during its lifetime.”
“The first principle is, if glass breaks, it should not be able to fall.”
These are typical incidents to consider in design. Never be afraid to do some research too. As you design, specify and prepare for installation, do an internet search on other potential areas of risk. In being thorough you may just avert a future tragedy.
“Never be afraid to do some research … on other potential areas of risk.”