English Heritage plans survey for all Grade II listed buildings
All of England's Grade II listed buildings are to be surveyed by English Heritage for the first time.
The body is calling for an "army of volunteers" to determine which of the 345,000 are at risk from neglect.
The process is part of the body's annual heritage risk survey but will take several years. More than 700 buildings were identified as needing attention during pilot programmes.
English Heritage itself only collects information on buildings within London.
The body has announced its first crowd-sourced programme to extend the programme to the rest of England.
"For English Heritage it means we will eventually get, for the first time, a complete picture of the condition of all England's listed heritage," said Simon Thurley, chief executive of English Heritage.
He added: "We can use this information to decide how best to deploy our national expertise to help owners and all those tackling heritage at risk on the ground."
As part of pilot programmes run across the country, 350 volunteers inspected more than 5,000 Grade II listed buildings.
They found that 4.2% were at risk and 10.1% were vulnerable.
The pilot projects surveyed buildings in a number of areas.
Among those found to be in need of attention were The Ruins of Old Buckingham House, in Shoreham-by-Sea, in West Sussex. The original building, built in 1820, was badly damaged by fire in 1910. English Heritage said the surviving structures were in increasingly poor condition.
Volunteers also identified Big Mill in Leek, Staffordshire, Llanthony Provender Mill, in Gloucestershire and the western lock on the Northern By-Pass Channel at Appley Locks, in Lancashire.
Launching the Heritage at Risk Register 2013, English Heritage asked for more volunteers to come forward in order to cover the rest of England's Grade II structures.
English Heritage said that, during the programme's pilot phase, volunteers surveyed an average of 13 buildings per day each following a day and a half's training.
In Whitehaven, Cumbria, they picked out the former YMCA building, an 18th century structure vacant for a number of years, as in need of repair.
They also singled out the former Methodist Church in the town, which was designed by architect TL Banks. It was built in 1877 but has deteriorated and now stands with broken windows and crumbling stonework, English Heritage said.
David Day, who volunteered in Whitehaven, said: "Many of us are concerned about the neglect of local buildings that are crucial features of our town.
"We are worried that we will literally lose sight of the past and in so doing we lose the chance to understand the present."
Ann Buck, a volunteer in north Norfolk, said: "These buildings are our heritage and the fact that we have lost so many is tragic.
"English Heritage and the National Trust are the last resort for a lot of them, we are never the owners of such buildings, just the custodians."
English Heritage said some councils already kept lists of structures and what condition they were in, which the volunteers would help to update.
In other areas, they would be asked to create a list from scratch. The number of Grade II structures judged to be in need of some repair is expected to grow as a result.
Mr Thurley said: "We will have a grass-roots network to spread understanding and appreciation of local heritage so that less of [the buildings] become at risk in the first place.
"One pilot project even passed details of buildings found to be vacant and vulnerable to the police and fire services, making them better aware of places likely to attract crime."
The project is being launched at the Granary Building in central London - a Grade II building rescued from dereliction as part of the redevelopment of the King's Cross railway lands.
English Heritage said it hoped to begin recruiting for the first full surveys next autumn and asked would-be volunteers to contact its customer services department.