Guidelines For Rehabilitating Historic Buildings: Windows
GUIDELINES FOR REHABILITATING HISTORIC BUILDINGS: WINDOWS
U.S. Department of the Interior
National Park Service
Preservation Assistance Division
An illustrated booklet addressing the Secretary's Standards and the
guidelines is available from the U.S. Government Printing Office.
The title is "The Secretary of the Interior's Standards for
Rehabilitation & Illustrated Guidelines for Rehabilitating Historic
Buildings", ISBN 0-16-035979-1.
Each of the guidelines included in the booklet mentioned above have
been separated into individual entries for specific use in HBPP.
This entry represents one of many guidelines included in the
booklet and describes RECOMMENDED and NOT RECOMMENDED applications
of the Secretary of the Interior's Standards as they relate to
Windows. For a list of the Secretary of the Interior's Standards
for Rehabilitation, see 01091-04-S; For general information
relating to the purpose, organization and content of the individual
guidelines, see 01091-05-S. Both of these entries should be
referenced along with the information contained in this document.
A highly decorative window with an unusual shape, or glazing
pattern, or color is most likely identified immediately as a
character-defining feature of the building. It is far more
difficult, however, to assess the importance of repeated windows on
a facade, particularly if they are individually simple in design
and material, such as the large, multi-paned sash of many
industrial buildings. Because rehabilitation projects frequently
include proposals to replace window sash or even entire windows to
improve thermal efficiency or to create a new appearance, it is
essential that their contribution to the overall historic character
of the building be assessed together with their physical condition
before specific repair or replacement work is undertaken.
IDENTIFYING, RETAINING AND PRESERVING
- Identifying, retaining, and preserving windows -- and
their functional and decorative features -- that are
important in defining the overall historic character of
the building. Such features can include frames, sash,
muntins, glazing, sills, heads, hoodmolds, panelled or
decorated jambs and moldings, and interior and exterior
shutters and blinds.
- Removing or radically changing windows which are
important in defining the overall historic character of
the building so that, as a result, the character is
- Changing the number, location, size or glazing pattern of
windows, through cutting new openings, blocking-in
windows, and installing replacement sash which does not
fit the historic window opening.
- 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.
- Obscuring historic window trim with metal or other
- Stripping windows of historic material such as wood,
iron, cast iron, and bronze.
PROTECTING AND MAINTAINING
- Protecting and maintaining the wood and architectural
metal which comprise the window frame, sash, muntins, and
surrounds through appropriate surface treatments such as
cleaning, rust removal, limited paint removal, and re-
application of protective coating systems.
- Failing to provide adequate protection of materials on a
cyclical basis so that deterioration of the windows
- Making windows weathertight by recaulking and replacing
or installing weatherstripping. These actions also
improve thermal efficiency.
- Retrofitting or replacing windows rather than maintaining
the sash, frame, and glazing.
- Evaluating the overall condition of materials to
determine whether more than protection and maintenance
are required, i.e., if repairs to windows and window
features will be required.
- Failing to undertake adequate measures to assure the
preservation of historic windows.
- Repairing window frames and sash by patching, splicing,
consolidating or otherwise reinforcing. Such repair may
also include replacement in kind of those parts that are
either extensively deteriorated or are missing when there
are surviving prototypes such as architraves, hoodmolds,
sash, sills, and interior or exterior shutters and
- Replacing an entire window when repair of materials and
limited replacement of deteriorated or missing parts are
- Failing to reuse serviceable window hardware such as
brass lifts and sash locks.
- Using a substitute material for the replacement part that
does not convey the visual appearance of the surviving
parts of the window or that is physically or chemically
- Replacing in kind an entire window that is too
deteriorated to repair -- if the overall form and
detailing are still evident -- using the physical
evidence to guide the new work. If using the same kind
of material is not technically or economically feasible,
then a compatible substitute material may be considered.
- Removing a character-defining window that is unrepairable
and blocking it in; or replacing it with a new window
that does not convey the same visual appearance.
NOTE: THE FOLLOWING REPRESENTS PARTICULARLY COMPLEX TECHNICAL OR
DESIGN ASPECTS OF REHABILITATION PROJECTS AND SHOULD ONLY BE
CONSIDERED AFTER THE PRESERVATION CONCERNS LISTED ABOVE HAVE BEEN
DESIGN FOR MISSING HISTORIC FEATURES
- Designing and installing new windows when the historic
windows (frame, sash and glazing) are completely missing.
The replacement windows may be an accurate restoration
using historical, pictorial, and physical documentation;
or be a new design that is compatible wit the window
openings and the historic character of the building.
- Creating a false historical appearance because the
replaced window is based on insufficient historical,
pictorial, and physical documentation.
- Introducing a new design that is incompatible with the
historic character of the building.
ALTERATIONS/ADDITIONS FOR THE NEW USE
- Designing and installing additional windows on rear or
other non-character-defining elevations if required by
the new use. New windows openings may also be cut into
exposed party walls. Such design should be compatible
with the overall design of the building, but not
duplicate the fenestration pattern and detailing of a
- Installing new windows, including frames, sash, and
muntin configuration that are incompatible with the
building's historic appearance or obscure, damage, or
destroy character-defining features.
- Providing a setback in the design of dropped ceilings
when they are required for the new use to allow the full
height of the window openings.
- Inserting new floors or furred-down ceilings which cut
across the glazed areas of windows so that the exterior
form and appearance of the windows are changed.
END OF SECTION