Legislation designed with the aim of protecting the country's architectural heritage could have the effect of actually discouraging owners of listed buildings from carrying out badly needed repairs and desirable improvement works, a number of leading architects have warned.

Practitioners are concerned that provisions of the Local Government (Planning & Development) Act 1999, which deal with the protection of structures of special architectural interest, could lead to a big increase in the amount of bureaucracy which property owners could encounter when planning alterations to their property.

The Act, which came into force at the start of the year, introduced the concept of the "protected structure". In Dublin alone, it is understood that there are around 9,000 buildings in this category.

By mid-June of this year, all the owners of these buildings should have received written notices informing them that their property falls into the category of "protected structure". Under the Act, all buildings that are listed are now "protected" regardless of the grade of the listing.

In other words, the same restrictions on alteration will apply whether the building is a listed structure of international importance, or one regarded as being of local significance.

Owners of protected buildings are obliged to secure permission from their local authority when they want to fix their windows; if they go ahead and remove old windows without getting the necessary approvals, they could be forced to reinstate the old windows, according to John Graby, director of the Royal Institute of Architects.

Normally, so called "minor" works to structures - for example, plastering or painting interiors - do not require planning permission. This is not the case with protected structures. The key question is whether the work will affect the character of the structure.

Owners or occupiers may request a local authority to issue a declaration indicating the types of works that can be carried out without affecting the "character" of a structure and do not therefore require planning permission. It is stated in the legislation that the local authority will issue such a declaration within three months. However, in practice, there is a question mark over whether the local authorities will have the number of staff to be able to do that work in the given time.

And, as is so often the case, the laws will not be applied equally across the board. Local authorities have varied considerably in the zeal in which they have listed buildings. The local authorities in Cork and Dublin, for example, have been very active when it comes to listing structures. Elsewhere, many local councils have been far less active.

Very important buildings in areas such as Donegal are without protection, while at the same time, modest outhouses beside dwellings in Dublin find themselves wrapped in the architectural equivalent of cotton wool.

The new provisions on protected structures are tied in with plans to establish a National Inventory of Architectural Heritage covering the entire country, contained in legislation passed into law a year ago. The Act in question is the Architectural Heritage (National Inventory) and Historic Monuments (Miscellaneous Provisions) Act 1999.

Requirements with respect to protected structures are being introduced before there is a proper list of such buildings in place.

In practice, it could take 20 years for a full inventory to be compiled. Clearly, the authorities cannot afford to wait this long as it is likely that in the intervening period, many buildings will have been swept away in a wave of development. To a degree then, the new requirements serve as a form of pre-emptive strike at a time when the country's historic building stock is being subjected to often ill thought out and poorly executed "restoration" and refurbishment.

Architects fear that the weapon of choice being used is the blunderbuss and they are concerned that genuine improvement works will be held up because of bureaucracy.

The new requirements will undoubtedly impose a huge burden on local authorities, who are supposed to appoint the necessary conservation officers to supervise the whole process.

IN practice, many local authorities have yet to do so. In Dublin, the number of conservation officers to cover a huge area is tiny.

Architects are confident that lack of resources will not mean that owners can get away with disregarding the new provisions. Neighbours and local community groups should see to that.

The real risk is that owners will be left in a state of limbo wondering whether they can go ahead and repaint their exteriors, remove old sheds, alter windows, or repair cracks.

The fear is that people will defer necessary remedial work because of the climate of uncertainty that has been created.

At the same time, owners or occupiers will be under a duty to ensure that the protected structure does not fall into a state of disrepair, a common enough occurrence where buildings are earmarked for redevelopment.

To be listed as a protected structure, a building does not have to possess importance, from an architectural heritage point of view, in its own right. It may be considered of importance because of its location - for example, where it is part of an established streetscape, or is beside an old church.

Architects fear they will be left in the dark when advising clients wishing to carry out works on protected buildings.

As yet, there are no guidelines on what should be included in planning applications that refer to such buildings.

It is the duty of an architect to issue an "opinion of compliance" with planning. This is an important legal document. Practitioners are concerned that they could end up issuing opinions which turn out to be incorrect.

"If I take out a glazing bar in a window, will I be able to stand over this action later?" asks one concerned architect. Further down the line, it is possible that conveyancing solicitors involved in transactions concerning protected structures could encounter problems. Checks will certainly have to be carried out to ensure alterations to the properties in question were not in breach of the 1999 Act and the guidelines introduced on foot of it.

Robin Mandal, Chairman of the RIAI's Historic Buildings Committee, is pleased that the legislation has been introduced but also worried about its likely impact.

"As someone who has worked in this field trying to secure this legislation, even I am concerned at its impact. My big concern is that the resources required to put the legislation into effect are not being made available to the planning authorities."