The “reconstruction” of historic urban cities is a complex endeavour, which includes many different intervention modes and methodologies, dependent on which scales (from individual buildings to the urban fabric), which historic or architectural qualities, and which degrees of destruction are concerned.
In the following, an attempt is made to define the scope and content of the main technical terms used in the Toolkit, in order to clarify the respective implications and to avoid confusions with regard to the various operational measures proposed.
Conservation / Preservation
These more or less identical terms apply to important historic monuments and involve the actions necessary to maintain the existing form, the original materials and the overall integrity of such a building without altering its structure, function or existing historical and architectural features. While maintenance and stabilisation works intended to arrest or redress the deterioration of the structural conditions are allowed, this does not include reconstruction of substantial parts of the building, nor removal of accretions, or adaptive re-use works.
This term indicates the insertion of new, morphologically and typologically compatible structures on irretrievably ruined plots, particularly in traditional residential districts. While an infill structure does not have to be an identical reconstruction of previous conditions, it should adapt itself to the historic environment and help consolidate the overall physical and social context of the historic urban fabric.
When used on the overall urban scale, this is the most generic term to comprehensively designate a variety of activities that can go from conservation and restoration (see below) to rebuilding parts of the city, either in terms of repair, of morphologically faithful substitution, or of introducing new structures on ruined areas.
When used on the scale of individual buildings (and particularly monuments), the term reconstruction means, more specifically, reproducing a totally destroyed historic building as a faithful replica of the lost structure – if possible by integrating fragments of the old building found on site. According to certain conservation charters, this procedure is “illicit”, however it is widely used in the exceptional case of landmark buildings affected by war damage.
Recovery / Rehabilitation / Adaptive Re-use
The terms “Rehabilitation” and “Recovery” apply mostly to the urban scale and are based on the analogy between the urban structure and a living organic system. They indicate the process of re-establishing the historical fabric’s original functionality, or complementing it with modern utilities through adapted interventions. They allow for efficient contemporary use of the urban structure, without substantially altering its historical features, nor compromising its architectural and cultural significance.
This term applies to the urban scale and indicates a comprehensive and integrated planning scheme that may incorporate elements of conservation, but mainly deals with the renewal of larger patches of ruined urban fabric. Inasmuch as it respects the prevailing historic morphology, it is an operational component of urban rehabilitation and may also include substitution or replacement of destroyed buildings in the context of specific and coherently planned action areas.
Morphologically correct urban reconstruction of destroyed areas can become part of urban rehabilitation, especially if it responds to actual social needs and helps re-establishing the cultural identity of the place.
On the level of individual buildings, rehabilitation is equivalent to adaptive re-use of the given shell of historic structures, thus combining physical recovery with socially meaningful and culturally desirable functions.
This term applies mainly in regard to individual buildings that are part of the historic urban fabric but are not considered as major monuments, i.e., mainly houses and small commercial structures. Ideally, repair activities are supposed to be matching in spirit, proportions and materials the prevailing previous conditions, although certain flexibility is required, particularly concerning functional improvements and coping with contemporary needs.
In contrast to preservation, restoration of monuments implies the restitution of a structure, as it appeared at a particular point in time, through the selected removal of added elements and the replacement of missing components.
Restoration practices have often been controversial in the past, either because the period to which the building was to be brought back was based on arbitrary aesthetic preferences, or because the amount of removal and replacement was closer to a conjectural reconstruction than to a careful integration of original elements.
Substitution / Replacement
These terms apply mostly to ruined plots or groups of plots within the historic city which had been considerably altered (or badly “modernised”) and represented disturbing elements in the pre-war historic fabric. Rather than rebuilding them in similar ways, the opportunity should be used to conceive replacements that allow for better integration in the historic context and for the introduction of appropriate new functions.
Stabilisation is an emergency form of maintenance for important historic buildings, when considerable means are needed to consolidate them or re-establish weathertight conditions. Stabilisation should be limited to those actions needed to protect or repair the monument and should not normally entail changes or alteration of its original configuration. Any new structural reinforcement would normally be concealed, so as not to modify the appearance of the structure. In areas with high historical value, particular attention should be given to documenting and handling sub-surface remains, when new foundation works are needed.