The Secretary of the Interior's "Standards for Rehabilitation"
require that where historic windows are individually significant
features, or where they contribute to the character of significant
facades, their distinguishing visual qualities must not be destroyed.
Further, the rehabilitation guidelines recommend against changing
the historic appearance of windows through the use of inappropriate
designs, materials, finishes, or colors which radically change
the sash, depth of reveal, and muntin configuration; the reflectivity
and color of the glazing; or the appearance of the frame.
Windows are among the most vulnerable features of historic
buildings undergoing rehabilitation. This is especially the
case with rolled steel windows, which are often mistakenly not
deemed worthy of preservation in the conversion of old buildings
to new uses. The ease with which they can be replaced and the
mistaken assumption that they cannot be made energy efficient
except at great expense are factors that typically lead to the
decision to remove them. In many cases, however, repair and
retrofit of the historic windows are more economical than wholesale
replacement, and all too often, replacement units are unlike
the originals in design and appearance. If the windows are important
in establishing the historic character of the building (see
fig. 1), insensitively designed replacement windows may diminish--or
destroy--the building's historic character.
This Brief identifies various types of historic steel windows
that dominated the metal window market from 18901950. It then
gives criteria for evaluating deterioration and for determining
appropriate treatment, ranging from routine maintenance and
weatherization to extensive repairs, so that replacement may
be avoided where possible. (1) This information applies to doityourself
jobs and to large rehabilitations where the volume of work warrants
the removal of all window units for complete overhaul by professional
This Brief is not intended to promote the repair of ferrous
metal windows in every case, but rather to insure that preservation
is always the first consideration in a rehabilitation project.
Some windows are not important elements in defining a building's
historic character; others are highly significant, but so deteriorated
that repair is infeasible. In such cases, the Brief offers guidance
in evaluating appropriate replacement windows.
(1) The technical information given in this brief is intended
for most ferrous (or magnetic) metals, particularly rolled
steel. While stainless steel is a ferrous metal, the cleaning
and repair techniques outlined here must not be used on it
as the finish will be damaged. For information on cleaning
stainless steel and nonferrous metals, such as bronze, Monel,
or aluminum, refer to Metals in America's Historic Buildings