It's a $2.6 million project but when completed visitors will be hard pressed to see what's different at the Whanganui Regional Museum.
The project is another of several the Whanganui District Council is carrying out to its public buildings.
The Royal Whanganui Opera House and Alexander library have been signed off and after the museum comes the War Memorial Centre.
Museum staff relocated most of the exhibits to temporary headquarters in Ridgway St last year before W&W Construction moved on site in January this year.
Rick Grobecker, council's project manager, said the physical work is on target to be finished in the middle of this month, a signal for the exhibits to be returned.
Mr Grobecker said while they had a good idea of what work was required it wasn't until the building had been cleared that they got a precise idea what they were faced with.
The building is a double brick wall construction similar to the Alexander Library building on Queens Park that has just been upgraded.
In the library workmen drilled from the exterior walls into the building to tie that bricks together and then recoated the outside walls.
At the museum the process has been reversed, with reinforcing tackled from the inside with a finishing layer covering up the work.
"There are some spaces we've opened up to give the staff greater working space.
"We've basically strengthened the building from the bottom up. Wherever there was a column we've got additional columns supporting them."
The only place the new steelwork can be seen in in the basement, an area where the public never goes.
Other remedial work included some resurfacing of the basement floor.
Since its initial, construction the building had sunk slightly creating an uneven surface.
The project price was set at $2.6 million which included $1.7 million for the physical works, a $250,000 contingency, $485,000 to relocate the collection off site and professional fees of $130,000.
Also included in the overall price was $175,000 for some deferred maintenance which took in reroofing the building as well as a significant internal electrical upgrade.
"Over time the wiring has been upgraded piecemeal and there wasn't a complete record of exactly what had been done so now is the ideal time to upgrade it completely," Mr Grobecker said.
Last year the museum received $400,000 from the Government's Regional and Cultural Heritage Fund towards the upgrade and museum director Frank Stark said it would enable more of the museum's treasures to go on public show.
That grant, coupled with $290,000 from the Lottery Grants Board, bequests and local fundraising will be used to install climate controlled vaults for the museum's natural history, taonga Maori and photographic collections, a new gallery for the Lindauer collection along with upgraded exhibition space, archives and general storage areas.
The museum is expected to reopen in October 2018.