WARWICK'S churches have plans to invest millions of dollars into renovation and restoration work in the coming years.

Already more than a million dollars has been spent restoring several of the Rose City's iconic churches in the past four years.

Among the biggest projects are the renovations at St Mark's Anglican Church, which are set to be finished for the 150th anniversary in 2018.

While the final cost of the renovations is yet to be determined, St Mark's Reverend Rod Winterton said it would be between $900,000 and $1million.

Among the work to be done on the church is $200,000 in restoring the iconic stained glass windows, which have started to bow in places.

Timber flooring has also been damaged by termites, while sandstone has begun to crack and break off.

Rev Winterton said replacing 80-year-old wiring and termite-infested timber was a priority.

"We want to have the main stuff done for the 150th anniversary," he said.

"We're looking at $600,000 for stone work and $80,000 to $90,000 for electrical work."

To raise money for the work, the Anglican parish has sold more than $150,000 worth of surplus land.

Money has also been raised through the Heritage Weekend and Parish Fete.

St Mark's, along with St Mary's Catholic Church have both set up restoration funds with the National Trust to raise money.

Over at St Mary's at least $700,000 has already been spent on restorations since 2012.

The 90-year-old church will need another $750,000 worth of work, including the removal, restoration and re-installation of stained glass windows.

Grout in sections of the church's sandstone walls has come loose, allowing water to seep into the walls.

Father Franco Filipetto said work was also being done on a smaller church in the St Mary's lower school campus.

"We've been restoring that out of our funds," he said. "We recently received an Everyone's Environment Grant for $40,000 to fix the back wall of the old church."

Fr Franco said St Mary's, like every church in Australia, was facing a decline in the number of parishioners.

"It certainly makes it harder for us to do the restorations," he said.

"They (the parishioners) would like to see the church restored. They've been very supportive."

The St Mary's Parish hopes to have restorations completed in time for the church's centenary in 2026.

Meanwhile the Warwick Baptist Church also has major plans.

A major redevelopment, estimated to cost as much as $10million is planned for the Guy and Percy St site.

The long-term plan will take at least 15 years and include a 600-seat auditorium and conference facilities.

Senior Pastor Darren Muller said a shorter term restoration project was planned for the sandstone church on Guy St.

"We're still in the process of finalising the costing but we estimate it will be around $300,000," he said.

The Wesleyan Methodist Church on Wood St is also undertaking renovations, although on a smaller scale.

Work has started to give the 60-year-old church a much-needed facelift.

Pastor Doug Baigrie said the wooden stumps underneath the church had started to decompose.

"The church had been in a sad state of repair," he said.

"We've put in new steel stumps underneath and closed the perimeter of the church with Besser blocks."

A new covered entrance will also be built at the rear of the church, allowing wheelchair access and weather-proof access.

Overall the renovations are expected to cost between $40,000 and $50,000.

Work is to be completed in time for Christmas carols.