The opening of the Te Whare Taonga o Te Arawa Rotorua Museum has been delayed to complete more site investigations.
It is expected to open in 2025.
The museum is in the Bath House building which will also be delayed.
The Bath House was initially expected to open next year, however, construction of the Bath House building is likely to start in 2022 with a build time of about two years.
This is following a range of issues that came to light during the pre-construction phase, including the 1908 unreinforced pumice masonry structures, a heavy roof, and challenging geothermal conditions.
The category 1 heritage building, which is more than 100 years old, closed in November 2016 after being damaged by the 7.8-magnitude earthquake that struck Kaikoura.
The release of the Detailed Seismic Assessment of the building the following year showed it fell well below earthquake safety standards at 15 per cent of the National Building Standard.
Buildings that are at 33 per cent or below are considered earthquake-prone.
Rotorua Lakes Council operational group manager Jocelyn Mikaere said while pre-construction work and extensive asbestos removal has been completed the council was pausing construction while additional investigations take place.
She said taking this time now will ensure the best outcome.
"The Rotorua Bath House building is one of the most challenging and complex strengthening projects happening in New Zealand at the moment," she said.
She said the challenge of strengthening a heritage building on geothermal ground resulted in buildability and risk questions.
Additional expertise has been brought in to help resolve issues that came to light during the pre-construction phase to help inform the structural solutions for the building.
"It's important that we have the best information to get the right solution for the complexities we are dealing with.
This included unreinforced 1908 pumice masonry structures, a very heavy roof, and challenging geothermal ground conditions," she said.
"We want to ensure that when the strengthening and restoration of this iconic building are completed, it will be a safe and much-loved part of our community fabric for the decades to come."
Once information from the geothermal and structural investigations is provided by experts, the council will host several update events to inform the community on the progress of the project.
The Rotorua Museum team will start its engagement programme in the coming months, giving the community the chance to share stories, thoughts, and views throughout the exhibition design process.
It is estimated exhibition installation will take about 12 months with Rotorua Museum Te Whare Taonga o Te Arawa expected to open in 2025.