What do they do: Dublin City Council conservation officer Nicola Mathews is passionate about caring for our heritage, she tells Bernice Harrison

As well as bringing in a range of new rules and regulations, planning and development legislation in 2000 also introduced a new job category to the local authorities: the conservation officer.

There's something about the title - maybe it's the "officer" part - that makes it sound censorious. When the legislation was introduced, many home-owners found that their quite modest Victorian redbricks were suddenly "protected structures" and that any changes they might want to make to their houses could involve a conservation officer.

Nicola Mathews has been such an officer with Dublin City Council for the past four years and she is a passionate advocate of the idea that "we are the custodians of our heritage". Her job is varied. There are 9,000 protected structures in the area covered by Dublin City Council. She says that in her experience "most people are well-intentioned about their buildings" but adds that sometimes, people don't necessarily understand the importance of maintentance or of getting work carried out using the appropriate materials and craftspeople.

She is passionate about the need to maintain roofs:much of the housing stock she has to look at is Georgian or Victorian, typically roofed with Blue Bangor slates which have a life expectancy of around 100 years - and which are now at a point in their life cycle where attention has to be paid.

"Basic things like broken gutters can cause a huge amount of problems unless dealt with," she says. "I encourage everybody on a job, from the homeowner to the architect, to get up on their roofs and see what's going on up there, it's really important." She spends her fair share of time on roofs, particularly when assessing conservation grants.

These grants typically are given to owners of protected houses to help with maintenance work on the roofs or windows. She admits that, at between €12,000 and €25,000, they are not designed to cover the entire cost of a job, but to ensure that appropriate high quality materials are used by contractors. The grants are to cover the shortfall between paying for an average job and a best practice one.

Mathews came to her current job after a 17-year career as an architect working on a range of mostly conservation-based projects, including conserving bijoux buildings for the Irish Landmark Trust and working on the crypt at Christchurch. She followed that with a Masters in Building Conservation, so she feels that her approach to buildings is informed both by years of practical experience as well as theory.

She refers to the current transformation of the Virgin Megastore at O'Connell Bridge into apartments and a new retail space as an example of how the planning process, informed by conservation guidelines, has helped guide the redevelopment of a building. "It could have been demolished but there are ways of retaining a building, conserving it in a sensitive way and getting new use out of it."What conservation-based legislation does, she says is "ask us to think about what we have and to value it".