Central Demolition is waiting for engineers to examine inside neighbouring properties to the Thain's building before completing demolition of it.
The engineers are working for the owners of the buildings to ensure they are structurally sound inside before Central Demolition resumes work.
When the engineers' work is finished, what remains of Thain's building will be demolished by Central Demolition within approximately two days.
Central Demolition managing director Ian Butcher said he was not sure when they will be able to resume work.
"It's not a big deal for us, we'll just shut the site down, keep it safe, then leave and come back when they're ready for us to tidy up the rest of it," Butcher said.
"The job has gone really well, there have been no major issues. We just took our time with it and made sure it was safe."
The Thain's building was left severely damaged after fire burned through it on July 20, injuring two people and triggering a fourth alarm for Fire and Emergency.
Sixty-five firefighters from 12 central crews battled the blaze on the corner of Taupo Quay and Victoria Ave for four hours before extinguishing it.
The fire caused partial collapses of the roof and interior floors, leading to the announcement that the Class B heritage building had to be demolished for safety reasons.
Demolition began on August 8 when Central Demolition built two platforms for excavators to sit on inside the building, working from back to front.
Butcher said Whanganui District Council had been really good to work with throughout the project.
"They've been so helpful with closing the roads and making it safe, all that stuff.
"Everybody was interested in making sure the process went smoothly and safely. They were awesome."
Central Demolition was able to salvage many materials, including bricks and timber, during the demolition process.
Many large beams were sold from the site to Whanganui locals while what remained was taken back to Central Demolition's Feilding yard.
Butcher said about 50 per cent of the floor was saved.
"We've got a whole lot of beautiful timber out of the place which is fantastic. They're beautiful matai beams and floors.
"All of those bricks have been brought back to our yard and we're in the process of cleaning them all up, putting them on pallets and selling them."
Butcher said there were thousands of bricks that are in high demand as workers chisel off the crumbly lime mortar with a tomahawk.
As work has been carried out, an archaeologist has visited the Thain's building site to investigate and is expected to return next week.
Central Demolition will be on-site when the archaeologist returns to help out by digging back some of the top soil if need be.
A police spokesperson said the Thain's building fire was an active investigation and they were unable to comment further at this stage.