The Sydney Opera House could have robots performing vital conservation checks on its roof within three to five years, reducing the need for workers to abseil across historic sails 67 metres above the ground.

Engineers at the University of Sydney developed a high-tech hammer that can test the condition of the tiles on the roof without damaging them.

"If we can find a way of electronic testing on board a robot of some sort, it would certainly be much cheaper and much easier — and safer," said Greg McTaggart, the director of building.

The aim is to integrate the hammer in a robot to provide real-time information about the condition of each tile as the building continues to age.

Sorry, this video has expired Maintenance workers inspect each tile on the sails of the Sydney Opera House

The two-year project was funded by the US-based charity the Getty Foundation, which sponsored 10 'Keeping it Modern' projects around the world with the aim of preserving the finest examples of modern architecture.

The foundation contributed $US200,000 and that was matched by the Sydney Opera House.

The concrete preservation project looked at the sails, the concrete "socks" at the foot of the sails and the northern boardwalk area.

Louise Herron, the chief executive of the Sydney Opera House, said preserving the structure was challenging because of its World Heritage status.

"This is the foremost 20th century building showing the use of concrete," she said.

"We need to ensure that we do everything we can to conserve it - without ruining it in any way."

Avoiding drilling was key, Greg McTaggert said.

"If we can find a non-invasive way of testing, like x-ray or ultrasonics, to determine what's going in with the concrete, it fits in much better with the heritage," he said.

Gianluca Ranzi from the University of Sydney says the hammer could be planted on maintenance robots. ( ABC News: Nicole Chettle )

Questions unanswered about construction process

Australia's most recognisable building remains cloaked in mystery. Much of the construction process was experimental, and the concrete sails were cast on site — but it's not clear how.

As part of this project, some of the original builders were interviewed to uncover some of the construction secrets, particularly where there were incomplete or inadequate records.

That information is being used by engineers at the University of Sydney, who have also made chevron-shaped "tile lids" to show how they might replace some of the original tiles and the concrete below them when the time comes.

It's a labour of love for Professor Gianluca Ranzi, who leads a team of student engineers.

"I used to be a clarinettist when I was growing up. So for me it was really an opportunity to bring back a love for music with a love for engineering," he said.

Lasers used to add to database

The Sydney Opera House also used lasers to scan the entire building inside and out, to create a 3D "fly-through" that included everything that was known about the building.

The idea is to create a central database, without having to "go trawling through people's garages to find information", Greg McTaggart said.

"They are really leading the field here", said Ton Wilmering from the Getty Foundation, praising the standard of conservation management planning in Australia.

"We feel that modern architecture is at risk ... it's important to balance the architect's intent with the needs and preservation of the material on the other hand."

Louise Herron said a modern marriage of technology and conservation could see Jorn Utzon's masterpiece grace Sydney Harbour for another 200 years.