Building conservation has been influenced and developed by a variety of philosophies and charters, primarily since World War II. These include the Venice Charter (1964), the Granada Convention (1985), the Burra Charter (1979-2013) and European Conventions on the Protection of Architectural and Archaeological Heritage (1997).

These charters have aimed to protect individual monuments and buildings, to the cultural significance of entire places such as cities and cultural landscapes. Area-based conservation is increasingly recognised internationally as a counterbalance to a homogenisation of world culture, as well as being encouraged by growth in cultural tourism.

Guiding Principles

The following are some of the guiding principles which influence prevailing conservation philosophy in Ireland and Europe:

Minimum intervention

Minimal intervention is the concept of low-key intervention which involves keeping as much and changing as little as possible. Over-restoration of historic buildings can be detrimental to their character and can result in a loss of tangible features and intangible charm. Instead, we should try and accept the worn appearance of old features and avoid removing all traces of imperfections. These are evidence of a building’s antiquity and contribute to its irreplaceable patina of age. The old adage, ‘little and often’ is especially relevant to old houses.

Repair rather than replace

Good conservation practice always seeks to retain old fabric that contributes to the special interest of a building. Unnecessary replacement of historic fabric can adversely affect the character of a building and diminish its authenticity and value as a source of historical information. Replacement fabric will never have the authenticity of the original, even if it superficially looks the same. Repairs can slow or arrest the process of decay and prolong the life of an old building without loss of character and authenticity. Replacement, if absolutely necessary, should be kept to the minimum to ensure that the building is left structurally sound and stable but not necessarily pristine.

Honesty of repairs and alterations

Repairs and alterations to old buildings should generally be of their time. Quite simply, new interventions or additions do not need to look old. Attempts to disguise or artificially age interventions should be avoided. However, there is no need for new interventions to be visually obtrusive or clash with the old in order to be honest. They should be discernible on close inspection but should not detract from the visual integrity of the original structure. New alterations and additions will, in turn, form part of the history of the building, so they should make their own positive contribution by being well-designed and constructed.

Use of appropriate materials and methods

The use of appropriate materials and methods in repairs and interventions is essential in order to ensure the long-term survival of an old building. Many materials such as cement and plastic-based products can damage traditional building materials and result in accelerated decay of the building. As a simple rule, use of ‘like-for-like’ materials and techniques is the best way of conserving an old building.

Respecting earlier alterations of interest

Later alterations and additions, such as porches and plate glass windows and certain decorative features can contribute to the character of an old building. In order to appreciate the overall integrity of a structure, it is always important to respect the contribution of different stages of its historical development. Fashions come and go, and a prevailing taste for removing certain features may deny future generations the opportunity of fully appreciating the historical development of an old house. Only in certain circumstances, based on research and informed judgements, should the removal of later alterations be considered.


Restoration means returning a building or structure to a known earlier state. Ideally, restoration should not result in the loss of historic fabric or features. For instance, it may be inappropriate to remove late 19th century plate glass windows in a Georgian house and replace them with 21st-century replicas of Georgian-style, small-paned windows. In other circumstances, it may be necessary or desirable to restore missing features such as windows, doors and joinery or plasterwork features during the course of repairs and renovations. In such cases, the design of new features should be based on physical evidence either from the subject building or adjoining houses in order to avoid conjectural restoration.


The use of techniques and materials which allow a repair or alteration to be reversed at a later date without loss of historic features or fabric is always to be preferred. Removal and disposal of old doors and windows is an obvious example of an irreversible intervention. A less obvious example would be the use of modern materials such as resin, concrete or cement which form a tough, almost unbreakable bond with old building materials, making reversibility without damage difficult at a later date.



Further Reading

For further information on building conservation philosophy and resources, visit our Resources page or purchase our indispensible Irish Period Houses Conservation Manual.