Research suggests there is a shortage of roofers in the UK
Millions of old buildings in England may be at risk because of a shortage of specialist workers, a report says.
The National Heritage Training Group said more thatchers, dry stone-wallers and stonemasons were needed to deal with pre-1919 construction.
It said the shortage of craft workers has eased in recent years, but there was still a skills and knowledge gap.
Peter Lobban, of industry group ConstructionSkills, said "giant steps" were being taken to train more people.
Research conducted for the report revealed that many people were finding it hard to find joiners, roofers and carpenters, while levels of satisfaction with repair work have declined "considerably".
The report also revealed that there are only 507 fully accredited conservation professionals in the UK from a base of half a million architects, engineers, surveyors and conservation officers.
The study showed this was equivalent to one accredited surveyor to every 85,000 old buildings, and one engineer to every 276,000.
According to the report, the future of the five million pre-1919 buildings in England could be at risk because of the lack of specialists.
Mr Lobban, who is chief executive of ConstructionSkills, said: "We've taken some giant steps to ensure that more people are taking up these traditional building crafts that are so important to preserving the country's heritage buildings.
"But there is more work to do. Many of the people undertaking repair and maintenance work on pre-1919 buildings need upskilling to guarantee that tasks are completed to the highest possible standard and England's iconic and more humble buildings are not spoilt."
Meanwhile, Bill Martin, director of conservation at English Heritage, said the "serious shortage of craftspeople" had been highlighted in a 2005 report which "captured the imagination of many people and has resulted in a huge renewal of interest in careers in the heritage build sector".
He went on: "The 3000-strong force of new blood is crucial to addressing the succession problem within the sector. We may be reversing a trend but clearly there is still lots to do to make sure the quality of work is maintained.
"These skills issues affect not just listed buildings, but the whole swathe of undesignated and locally important heritage and conservation areas that form an integral part of the historic environment."
The National Heritage Training Group and its partners said it will invest £1m to help reduce the skills gap through various initiatives, such as encouraging the up-take of qualifications such as the Heritage Skills NVQ Level 3 and a Heritage Apprenticeship Programme.
It also plans to establish a mentoring programme, with experienced craftspeople passing on skills and knowledge to less experienced practitioners.
Mike Moody, chairman of the National Heritage Training Group, stressed the importance of "retaining a skilled workforce".
"This is essential if we are to maintain the highest possible standards of workmanship, as well as remaining commercially successful," he said.
Mr Moody went on: "The work of the NHTG has helped reduce the skills shortage, but we will now redouble our efforts to address the skills gaps for both craftspeople and building professionals to ensure we properly care for and maintain our built heritage."