Currently the term ‘restoration masonry’ has become synonymous with work in general on historic masonry buildings. From common interventions such as repointing, to stone or brick replacements, to crack repairs and rebuilding, restoration has become a buzzword used to encapsulate all heritage masonry work.
The restoration approach is actually part of the larger field of architectural conservation, which has traditionally had different meanings, but is today defined by four distinct philosophical approaches. Each of these approaches has its own unique characteristics, goals and set of priorities. Although they differ in many ways, they do share common elements: They are all preceded by careful research and inspections, and once implemented, they follow a careful set of processes from start to finish. Most importantly, each of the following four approaches seeks in its own way to express the historical character of the building in question.
The main function of the preservation approach according to the U.S. Department of the Interior, is the retention of all historic fabric through maintenance and repair. This approach is focused on maintaining a historic property in its existing state. This is done through identifying causes of decay such as chemical or water sources and removing those threats.
The restoration approach seeks to return a structure to its original concept. Restoration techniques are often applied once it can be established that the form of a building at one point in time outweighs in importance its configuration at other periods of time. This philosophy relies on archaeological evidence and documentation before making any changes to the structure. As well, any replacements to the fabric of the building must be distinguishable from, while integrating with the original elements. Historical additions are for the most part preserved, unless the removal of such additions reveals a feature of great historical interest. Restoration allows for some modern building materials, provided that they are structural in nature and that all visible aspects of the house remain traditional.
Rehabilitations focus on adaptations to historical properties based on different considerations, such as economic factors and historical value. The adaptation is undertaken to give the building a new functionality, while at the same time respecting the overall historical character of the site. This is done through preserving existing architectural features, and simplifying additions to maintain harmony with the original structure. Finding a use for the building that is similar to its original function is ideal, as it often requires fewer changes to the building, however ensuring a usefulness for the building is often a primary concern.
This approach is employed when parts of a structure are lost over time, or when disasters such as fire necessitates the recreation of the structure. Reconstruction is always based on solid evidence and documentation, and conjecture is not permitted in determining structure or features of the building. Research evidence and physical evidence are the two primary sources of information for conservators employing this approach. Moving an existing building can be considered reconstruction, but it is only considered when there is a significant benefit to public interest, as there are often environmental variables that differ from place to place and can subject the building to unanticipated threats.
*A note on renovations:
Renovation is less a philosophy and more a process that focuses on updating a building, modernizing character elements or bringing it up to current standards. Renovations are not necessarily constrained by respect for historical characteristics, and in a renovation the function of the new work takes precedence over the existing structure. Renovations are undertaken mainly in new buildings, where improved functionality is needed, and it makes more sense for the owner to add or alter the existing structure than to find a new building.