Members of a Bradford church, which is one of the few 18th century churches in Yorkshire, are trying to raise £275,000 to save it from closure.
Damage was discovered to St John's Church, a Grade II listed building on Rooley Lane, last November in a church report.
The report found that the combination of old age and a heavy roof have led to serious problems within the building, including cracking masonry.
The survey also found that another cause could be subsidence due to old mines and iron ore extractions, common throughout Bierley.
The church is known as one of the finest examples of Georgian architecture in Bradford.
The church has applied to English Heritage for help to prevent any further subsidence, but because many of the mines do not appear on plans there is no evidence to prove this theory.
Church warden Robert Smith said: "This is a matter of debate with English Heritage. We have applied for £275,000 but they are not prepared to provide a grant until they know the exact cause.
"Once we can prove the damage English Heritage will know what action needs to be taken. But whatever the outcome of that, just to repair the masonry and the roof is going to cost £150,000."
"It is safe at the moment but if we don't take action now five years down the line it may not be safe and may have to close."
To provide evidence of damage to the church the church must undertake a new geophysical survey, which will involve boring spy holes near the building and placing a camera inside to find out the full extent of the mine cavities under the church.
The survey will cost another £25,000 but English Heritage have indicated they will pay 85 per cent of the cost.
Members of St John's Church are working hard to raise the money needed.
But Ward Councillor John Ruding (Tong, Lab) believes it will prove difficult.
He said: "The costs involved are beyond the means of the normal congregation.
"It is a beautiful Georgian building and it would be really sad if anything serious was wrong with it.
"I am not sure if English Heritage is going to contribute but I am sure several local charities would be happy to help, I believe we can overcome the difficulties with the community's help."
Christine Gray, from English Heritage, said: "The Church has applied for a grant under the Joint Churches Scheme. If the application is successful we will be working closely with them."
The second oldest Anglican church in Bradford, St John's was built in 1788 by John Carr of York, a leading architect of his day who also designed Harewood House in Leeds.
Members of the dwindling congregation are also having to cope with the added problem of not having a vicar since the Reverend Iain Lane moved on 15 months ago.
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