Gaston said in light of this, it was decided to delay moving in and opening to the public until the building and surrounds were fully finished, rather than doing a "soft opening" and operating around work.
He confirmed the delays would not cause any additional cost to the project.
"Delays had crept in during recent weeks, prompting the decision to take January to prepare for an early February opening," Gaston said.
The project is jointly funded by the council and the Lakes District Health Board, which will become a long-term tenant in the building, providing outpatient child health services.
The DHB was not able to be moved in by the November opening so the delay meant the facility could now open with both services on site.
Mayor Steve Chadwick said the decision to delay the opening was "a very logical call" and would enable the project partners to showcase how co-location can work.
"While it's disappointing and I want it open, I'd rather it is fully finished and operational when it is opened so people get a real sense of how it will work."
Councillor Charles Sturt said he had thought opening on November 25 was "ambitious" and he too preferred the whole facility was operational before it opened to the public.
Fletcher Construction Waikato Bay of Plenty manager Mark Ritchie said there were huge pressures on resources throughout New Zealand, not just in Rotorua.
"There is nothing sinister in it, in the end it was a sensible decision that was made to take a breath and extend the timeframe, rather than rush and push this through."
Ritchie said there there were no factors particular to this project's construction that had made it hard to find workers.
"This has been a reasonably significant refurb of an existing building, but nothing out of the ordinary."
The additional time to prepare for the move would also enable the council to minimise the time library services would be unavailable.
Lakes District Health Board chief operations officer Nick Saville-Wood said the services that were to move into the redeveloped building would continue to operate from their current premises until a new transfer date was confirmed.
Rotorua Library director Jane Gilbert said library services would continue as normal.
"We had begun preparations for moving back to Haupapa St and were excited about the opening and the new services and features library users will be able to enjoy. We are obviously disappointed but the delay has been unavoidable and we will adjust our plans accordingly," she said.
The library will continue to operate in its Pukuatua St premises in the interim.
