on conjectural designs or the availability of different
architectural elements from other buildings or
The surface cleaning of structures shall be undertaken
with the gentlest means possible. Sandblasting and
other cleaning methods that will damage the historic
building materials shall not be undertaken.
Every reasonable effort shall be made to protect and
preserve archeological resources affected by, or
adjacent to any project.
Contemporary design for alterations and additions to
existing properties shall not be discouraged when such
alterations and additions do not destroy significant
historic, architectural or cultural material, and such
design is compatible with the size, scale, color,
material, and character of the property, neighborhood,
Wherever possible, new additions or alterations shall be
done in such a manner that if such additions or
alterations were removed in the future, the essential
form and integrity of the structure would be unimpaired.
The guidelines for applying the Standards were developed in 1979
and revised in 1983. They pertain to historic buildings and
structures of all sizes, types, materials, and uses. They apply
to both interior and exterior work. They set up a hierarchy for
the treatment of old buildings, from the most to the least
desirable ways of handling rehabilitation projects, as follows:
Identify, retain, and preserve the form and detailing of
those architectural materials and features that are
important in defining the historic character.
Protect and maintain the materials and features that
have been identified as important. Protection generally
involves the least amount of intervention and may
include maintenance measures such as rust removal,
caulking, cyclical cleaning of roof gutter systems, or
installation of alarm systems or fences.
Repair historic materials and features, beginning with
the least amount of intervention possible.
Replace character-defining features in kind, that is,
with the same material whenever possible, or with
compatible substitute material when necessary.
Replacement should occur only when the feature is too
badly deteriorated or damaged to repair.
Reproduce missing historic features only if adequate
historic, pictorial, and physical documentation exist to