Imagine a little thatched cottage hidden high up in the hills of Donegal. Now picture a family of four little boys who come with their parents to refurbish the ruined structure. It was an awfully big adventure.

When they worked, they lost track of time, hammering and hauling bricks late into the evening. They rebuilt and plastered walls. They worked on the thatched roof, which ultimately had to be replaced. They sawed and hammered, measured and carted supplies. They kept many of the traditional features such as the open hearth, the little windows, the slate floors.

"It was dirty work," says Gavin Wallace, who was aged 12 when his father bought the old thatched cottage high up in the hills of Glen, near Carrigart in Co Donegal. Wallace remembers the fun he and his three younger brothers had working on the derelict house. At weekends they left Ballymoney, Co Antrim, to stay in their caravan and work on the two-bedroom cottage.

His decision to study building surveying is largely due, he believes, to this conservation and renovation project, which took over a decade to complete. Today he is a building surveyor in Hamilton Osborne King on Dublin's Molesworth Street.

His job still has a hands-on element: "You are in and out of attic spaces, up and down scaffolding. You go on to sites quite a lot. I'm out all day a lot of the time."

His task is to offer "detailed advice on the design, construction, maintenance, management and repair of proposed or existing buildings". Building surveying is "the conservation or project management of older buildings", he adds.

"You have to be organised in that the jobs are so widespread and varied it's unbelievable - you have to be able to switch from one type to another." It's vital to meet deadlines also, he explains. Maths are important "to a certain extent", he says. "You have to be able to calculate angles." One of the most enjoyable features of the job is the variety and scope, as well as the fact that he's out of the office up to 50 per cent of the time. "You get to travel a lot all over the country," he adds.

A building surveyor must "have an eye for detail. Every surveyor does. You have to assess something, and you have to think about each job in a very logical way as to how you can get the final result. You have to be able to see the final product."

It's also important to have "an ability to design. You have to have ideas and portray those verbally and on paper. There's a lot of problem-solving. You find that with existing buildings."

He's worked in HOK for the past 11 months. He completed his GCSEs ( the Northern Ireland equivalent of the Junior Cert) at 16. Then, "I didn't have a clue what I wanted to do." He opted for a B Tech national diploma in land administration in Coleraine Technical College, Co Derry (now the Causeway Institute of Further and Higher Education). It was "brilliant", he says. They were brought on site where they could be found using theodolites. In college they learned how to use Auto-CAD in architectural design.

The two-year course was "extremely broad" with "a hands-on, practical approach". He graduated in 1994 and decided to study building surveying instead of architecture or town and country planning. He went to the University of Northumbria in Newcastle-upon-Tyne where he did a BSc (hons). "The course itself was very interesting," and included over a year's work experience with a Belfast-based company.

Having completed two years in professional practice, he will be assessed for membership of the Royal Institute of Chartered Surveyors next year, undergoing an assessment of professional competence exam as part of this. Although many people are still confused about building surveying and what it entails, he says "it is growing massively. In a few years it will be very big."