Why are there plastic bubbles on top of the National Library?

No, it’s not a ‘bookworm’.

The roof of the National Library of Australia is covered in long, white plastic bubbles, but before you think it’s some sort of literary sculpture – a very hungry caterpillar, perhaps? – hark back to 20 January 2020.

Like many roofs around the city and Belconnen, the Library was peppered with hail stones as big as golf balls, leaving the copper roof tiles looking much like a golf ball.

Acting Director of Capital Works Merika Behr says the plastic bubbles are in place while contractors rip up the tiles and repair the damage underneath.

“Preparation starts first and foremost with keeping water out of the building while they move across,” she says.

“We have to remove the storm seal in order to start removing the damaged copper roof sheets, which leaves the building exposed.”

While they’re in there, the workers are also cleaning up the roof space and fixing any of the timber trusses and battens that might have deteriorated over time.

“Then we’re putting down a new plywood substrate, and over the top, a blue waterproof membrane. These are new elements that will add extra support for the new copper roof but also add extra protection in the unfortunate event of a future hailstorm.”

The National Library of Australia at Parkes Place was opened on 15 August 1968 by Prime Minister John Gorton. Walter Bunning was the chief architect behind the ‘Contemporary Classical’ style, influenced by the Parthenon in Greece and the work of American architect Edward Stone.

At the time of construction, Prime Minister Robert Menzies openly criticised the idea of a modern building and preferred “something with columns”. Marble-clad columns it was, although the original plans included the same number of columns as the Parthenon before a row was cut to save $250,000.

Copper is copper, though, so not much can be done to make the new roof tiles more hail-resistant.

“It has to be rolled out in very thin layers so it can be formed into the right profile,” Marika says.

There was also the weight to consider.

“During the design and project, we had to consider the trusses and factor in how much extra weight we might be putting on the roof, just be having the copper up there plus the plywood and membrane.”

The second and third stages of construction will be a rinse and repeat of the first, moving back along the roof towards the Commonwealth Avenue Bridge.

Marika says that as the bubbles move on, we’ll be able to see the blue waterproof membrane before the first load of copper roof sheets is craned up from September.

“We bought 51 tonnes of copper from overseas which will cover an area of 12,100 linear metres. The maximum sheet length is 15 metres.”

They can’t afford for them to bend and twist so Marika says it will be a “very interesting exercise” lifting them onto the roof.

“Cradles will hold the full roof sheet and they’ll be lifted up to the roof on a crane and then stored so the roofers can lay them.”

Copper starts as orange-brown in colour but soon reacts with oxygen in the air to become a dull green.

“It will only be very, very shiny for a very short period of time,” Marika says.

The works are due to be completed this time next year, subject to weather, at a total cost of $14 million, covered by insurance from Comcare.

Canberra’s iconic Shine Dome was also damaged during the January hailstorm, and two years later, has just reopened after 1888 new custom-made copper tiles were laid.