Images of the fire that consumed the Grenfell Tower in London in 2017 shocked the world. As well as the tragedy of the loss of 72 lives, there was a reminder that high-rise living - so convenient to so many, relies on a lot of people doing their jobs properly before residents even move in.

Residents express their anger about the evacuation of the Opal Tower (inset). Credit:Dominic Lorrimer

It is a blessing that no such tragedy has befallen Sydney. But, as this city's population ticks over from 5 million to 6 million in the next decade, the proportion of inhabitants living high in the sky will only increase. Hemmed in by the natural barriers of mountains, national park and water, this is a city where the choice of housing comes down to urban consolidation - much unloved in the more established (and verdant) parts of suburbia - or going up.

The evacuation of the Opal Tower late last year was a wake-up call. Hundreds of residents were made homeless over the Christmas season after cracks appeared in the giant tower at Sydney Olympic Park.

Faults and installation mistakes in some of the prefabricated walls, positioned under beams that had been weakened by other work, caused the cracks. In one respect, it might be seen as a once in a lifetime event.