Being a sole survivor of war is a burden few ask for, but when you fall under the weather and weigh 22 tonnes, you can be sure to draw attention.

The Palm House in Adelaide's Botanic Gardens is undergoing its second restoration in about 25 years, with a team of painters and builders treating it for salt damp and rust incursion.

Plants have been moved out and cracked glass panes are being replaced, as workers utilise a huge freestanding scaffolding structure that took a week to build inside and around the 1877 structure.

Originally built in Bremen, Germany in 1875, the Palm House was shipped to Adelaide and reassembled, although the glass panes were all broken by the time it arrived.

Following the devastation of subsequent wars in Europe, it remains the only known German-built glasshouse from the era and is Australia's second oldest.

Andrew Carrick inspects a curved pane in the roof of the palm house. ( ABC Radio Adelaide: Malcolm Sutton )

Andrew Carrick from the Botanic Gardens and State Herbarium said there were similar examples of iron and glass botanical houses around the world, such as the Crystal Palace and the Kew Gardens palm house in London.

"They are the same style with the cast iron, and obviously at a much grander scale, but ours is probably the only one in the Southern Hemisphere," he said.

The structure is built with float glass, all of which is hand-crafted. ( ABC Radio Adelaide: Malcolm Sutton )

It is also possibly the only surviving example of a prefabricated glasshouse, and was originally used for tropical plants until rust incursion in the early 1990s led the gardens to change its use to dry plants from the southern and western tips of Madagascar.

Some plants remain inside during the refurbishment, but others have been taken out and potted for their return later, while those that could not be salvaged were propagated at a nursery at Mount Lofty.

"We're also sourcing them from around the country and the world," Mr Carrick said.

His team has removed 25 curved panes of glass for replacement so far, while others were being cleaned as part of the restoration's first stage.

"Stage two will involve the top area, the top finials and the top dome, but that will take quite a bit more engineering to get the scaffolding up and over the top in a free span," Mr Carrick said.

An original iron ladder still rests across half the top dome — designed to rotate around the dome for maintenance works.

Modern occupational health and safety standards do not allow its use.

"We don't do that sort of thing anymore," Mr Carrick said.

Scaffolding is freestanding and had to be balanced with counterweights. ( ABC Radio Adelaide: Malcolm Sutton )

The palm house was built with stainless steel gutters, which have been repainted. ( ABC Radio Adelaide: Malcolm Sutton )

The doors have been taken off site to be treated for corrosion and dust and will be reinstalled by hand.

The team is also working to preserve the original lead-based paint — originally applied for corrosion protection — as they paint over it using art brushes for accuracy.

"We've got to make sure we maintain that without disturbing it," Mr Carrick said.

"If we do have to disturb that, there's a whole heap of health and safety requirements, such as breathing apparatus, masks and all that sort of stuff.

"Everything's hand-painted down to one-eighth of an inch and [the painters] will be painting every bit of metal they can find."

Some four full-time painters have already spent up to eight weeks on the project and are expected to finish in late November.

"Then the horticulturists will plant it back up and hopefully there will be a December reopening for everyone to look at it," Mr Carrick said.

Painters are using art brushes to methodically paint over the steelwork. ( ABC Radio Adelaide: Malcolm Sutton )

Mr Carrick is also overseeing the restoration of the gardens' heritage-listed Boy and Serpent fountain, which was donated by philanthropist Robert Barr Smith and installed in 1908.

It is considered a very rare item and, despite a restoration in 2008, has fallen into disrepair and is being restored at a cost of between $120,000 and $150,000.

"That's been taken away and pulled apart piece by piece, completely blasted back to bare metal again," Mr Carrick said.

He said it would be filled and recoated with a paint that "will give it extra rigidity out in the elements".

"It receives no love because it's out in the elements 24/7 and that's going to come back in a bright and refurbished state."