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• Types of testing
• Testing services in area
• Issue of sampling on site
• Interpreting data

Architectural Evidence: Studying the Fabric of the Historic Building

Destructive Testing

Most investigations require nothing more than historical research, surface examination and non-destructive testing. In very rare instances the investigation may require a sub-surface examination and the removal of fabric. Destructive testing should be carried out by a professional only after historical research and surface mapping have been fully accomplished and only after non-destructive testing has failed to produce the necessary information. Owners should be aware that the work is a form of demolition in which the physical record may be destroyed. Sub-surface examination begins with the most accessible spaces, such as retrofitted service and mechanical chases; loose or previously altered trim, ceilings or floor boards; and pieces of trim or hardware which can be easily removed and replaced.

Non-destructive testing techniques do not damage historic fabric. If non-destructive techniques are not sufficient to resolve important questions, however, small "windows" can be opened in surface fabric at predetermined locations to see beneath the surface. This type of subsurface testing and removal is sometimes called "architectural archeology" because of its similarity to the more well-known process of trenching in archeology. The analogy is apt because both forms of archeology use a method of destructive investigation.

Photographs, video and drawings should record the before, during and after evidence when the removal of historic fabric is necessary. The selection and sequence of material to be removed requires careful study so that original extant fabric remains in situ if possible. If removed, original fabric should be carefully put back or labeled and stored. At least one documentary patch of each historic finish should be retained in situ for future research. Treatment and interpretation, no matter how accurate, are usually not final; treatment tends to be cyclical, like history, and documentation must be left for future generations, both on the wall and in the files.