The rare and valuable windows which were made in England before being shipped to Australia a century ago, had been overdue for restoration work for decades, Father Greg Bellamy said. But no-one was quite prepared for just how damaged the windows would be.

"The lead between the glass was like butter," the parish priest said.

"It was very, very weak. There was quite a lot of cracking and damage over the last hundred years from birds and tennis balls and other objects hitting them.

"So it was a big surprise to us to find that they were in worse condition than the older windows in the main body of the church."

The removal of the North-facing stained-glass windows of St Joseph's brings the overall restoration progress of the nearly 150-year-old church to stage three.

Stage one and two took place over the past two years and it's expected to take several more for the whole project to be completed.

The historic windows have been sent to the workshop of the stained-glass restorer on the NSW South Coast, where she will work on them over the next six months.

In early to mid 2021 the remaining stained glass windows of the church will be also removed from St Joseph's and put into storage to undergo similar restoration.

Despite being older than the North-facing windows which were recently removed, it was already obvious they would be less damaged due to them being less exposed to the unforgiving rays of the sun, Fr Bellamy said.

"A major issue, particularly in Australia, is the heat from the sun. Those windows we just took out have been expanding and contracting for over a hundred years," he explained.

"In terms of putting the windows back in the church, that will be at a future date. There is more work to done besides the stained-glass windows on repairing and restoring St Joseph's Church.

"There's problems with rising damp, there's problems with the spire, there's problems with leakage in the slate roof.

"So we would want to develop a conservation management plan and begin restoration of the entire church before we put the windows back in.

"We don't want to put brand-newly restored windows in while we're doing major construction work.

"So it may be at least a couple of years until the windows are put back in."

St Joseph's is due to celebrate its 150^th birthday next year, but due to the extent of work still needing to take place on the church, it was very unlikely the mammoth restoration project would be finished in time.

"We're not going to meet that deadline, but it's an important priority for me and for the parish to care for the heritage of our Catholic community as well as for an important, historically-valued building of Orange," Fr Bellamy said.

"It's part of respecting and caring for the contribution of previous generations as well as a civic duty to look after a beautiful building in the Orange community."

Despite the scale of the restoration project being carried out on St Joseph's, there would continue to be no interruption to church services, the parish priest said.

However, the huge gaping holes in the window frames where the stained-glass window have been for the past century, may take some getting used to.

"It's a big shock," Fr Bellamy said. "It's allowing a lot more light into the church... but we've been talking to the community a lot and everyone realises that we've got to have a period without them (the stained-glass windows) in order to preserve them in the long term, in order to keep the building beautiful."