Whatever building is built in the place of the quake-damaged Timeball Station in Lyttelton, it is hoped it can incorporate the iconic building's timeball mechanism, the Historic Places Trust says.

Cranes are arriving on site today to begin the slow process of dismantling the Category 1 historic building.

Historic Places Trust spokeswoman Priscilla Pitts told Radio New Zealand the 134-year-old building had sustained minor damage in the September 4 earthquake and plans were in place to repair it, but the February quake had damaged the building beyond repair.

"A huge section of one side of it has dropped out, the tower which houses the timeball mechanism is very badly cracked and is probably only being held together by the strengthening that has been done at the top of the tower.

"Every aftershock we've had a little bit more damage happens. It really is in a bad way."

Ms Pitts said as the building is being "dismantled" not demolished, each piece of material is being marked and stored to aid a potential future rebuild. The process is expected to take three months.

"We are going to be taking it done as best we can and with safety paramount, stone by stone, and piece by piece."

Once the building is stable the dismantling will cease and the next steps will be worked out from there.

"We will almost certainly be building something on that site - whether we will be replicating the former timeball completely, we don't know."

The Timeball Station was built in 1876 and was one of only five working Timeball stations in the world.

Flags at the station were used to communicate shipping advice to the town and its ball slowly dropped to signal the time to ships in the harbour.

Ms Pitts believed the timeball mechanism, which had been restored in recent years, was still intact. She is hopeful what will be built on the site will incorporate the working timeball.

"That's the point of the site in a way, that's what makes it such a key historic place, both nationally and internationally.

The building is insured, Ms Pitts said, and the Historic Places Trust has received offers of funding.

The project will "probably one the biggest" the trust has ever undertaken, and believed it will cost in the "millions" of dollars.