Griff Rhys Jones' Restoration programme is a big hit

Ty-Mawr Lime says its classes in old-style skills, in conjunction with the University of Wales, Lampeter, are unique and are set to attract more than 500 new students this year - some from as far afield as Australia and France.

The company, from Brecon, is championing and reviving the sort of building skills common among construction workers 100 years ago.

Homeowners are putting pressure on builders to restore period homes properly and they're coming to us to learn how to do it. Joyce Morgan-Gervis, Ty-Mawr Lime Ltd

The day-courses aim to give homeowners and builders the confidence to use traditional and ecologically friendly materials in their building work, such as sheep's wool insulation.

Joyce Morgan-Gervis, who runs Ty-Mawr Lime, in Brecon, with her husband, Nigel, said: "All the makeover programmes, such as Changing Rooms, Ground Force and Restoration have all played their part in attracting increasing numbers of students to our course.

"But the BBC's Restoration programme seems to have played the major role - it seems to realise that the work can't been completed within a few days.

"Homeowners are putting pressure on builders to restore period homes properly and they're coming to us to learn how to do it.

"We've also got homeowners who want to learn how to do the work themselves and even people from abroad. For instance, this year people from France, Jersey and Australia will attend the course.

Ty-Mawr also manufactures mortar specifically for period properties. Its current client list boasts Cardiff Castle, Worcester Cathedral and Cardigan Castle.

"We've been running the course for a few years, but this year is the first time we've joined forces with Lampeter university and it has accredited the course," added Mrs Morgan-Gervis

Cardigan Castle dates back to the 12th Century

The University of Wales, Lampeter, claims there is a serious shortage of skilled conservation workers yet the country has thousands of historic buildings that require sensitive treatment to survive.

Dr Greg Stevenson, course assessor, said: "There is a desperate skills shortage in Wales for specialised conservation work, yet we have thousands of historic buildings that need to be treated sensitively if they are to survive.

"Modern materials like concrete, Portland cement and plastic paints do our old buildings more harm than good.

"These courses show people how using traditional materials such as lime and linseed-oil based paints help their buildings to breathe.

"The chances are that if your home was built before 1900 it was built with these products.

"Their modern replacements only trap damp into our homes, so we need to reach out to homeowners to show them how to treat their old buildings with respect."