Choosing Rehabilitation as a Treatment
In Rehabilitation, historic building materials and
character-defining features are protected and maintained
as they are in the treatment Preservation; however,
an assumption is made prior to work that existing historic
fabric has become damaged or deteriorated over time
and, as a result, more repair and replacement will be
required. Thus, latitude is given in the Standards for
Rehabilitation and Guidelines for Rehabilitation to
replace extensively deteriorated, damaged, or missing
features using either traditional or substitute materials.
Of the four treatments, only Rehabilitation includes
an opportunity to make possible an efficient contemporary
use through alterations and additions.
Identify, Retain, and Preserve Historic Materials
and Features
Like Preservation, guidance for the treatment Rehabilitation
begins with recommendations to identify the form and
detailing of those architectural materials and features
that are important in defining the building's historic
character and which must be retained in order to preserve
that character. Therefore, guidance on identifying,
retaining, and preserving character-defining features
is always given first. The character of a historic building
may be defined by the form and detailing of exterior
materials, such as masonry, wood, and metal; exterior
features, such as roofs, porches, and windows; interior
materials, such as plaster and paint; and interior features,
such as moldings and stairways, room configuration and
spatial relationships, as well as structural and mechanical
systems.
Protect and Maintain Historic Materials and Features
After identifying those materials and features that
are important and must be retained in the process of
Rehabilitation work, then protecting and maintaining
them are addressed. Protection generally involves the
least degree of intervention and is preparatory to other
work. For example, protection includes the maintenance
of historic material through treatments such as rust
removal, caulking, limited paint removal, and re-application
of protective coatings; the cyclical cleaning of roof
gutter systems; or installation of fencing, alarm systems
and other temporary protective measures. Although a
historic building will usually require more extensive
work, an overall evaluation of its physical condition
should always begin at this level.
Repair Historic Materials and Features
Next, when the physical condition of character-defining
materials and features warrants additional work repairing
is recommended. Rehabilitation guidance for the repair
of historic materials such as masonry, wood, and architectural
metals again begins with the least degree of intervention
possible such as patching, piecing-in, splicing, consolidating,
or otherwise reinforcing or upgrading them according
to recognized preservation methods. Repairing also includes
the limited replacement in kind--or with compatible
substitute material--of extensively deteriorated or
missing parts of features when there are surviving prototypes
(for example, brackets, dentils, steps, plaster, or
portions of slate or tile roofing). Although using the
same kind of material is always the preferred option,
substitute material is acceptable if the form and design
as well as the substitute material itself convey the
visual appearance of the remaining parts of the feature
and finish.
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This two-story brick commercial building--with its corner storefront--was originally constructed ca. 1876, then remodeled in 1916 in the Craftsman style and given a new, distinctive roofline. It served a number of uses, including a hotel, boarding house, saloon, restaurant, liquor store, warehouse, and office furniture showroom. The red brick walls had been painted several times over the years. Rehabilitation work included removal of multiple paint layers using a chemical stripper and thorough water rinse; spot repointing with matching mortar; and appropriate interior alterations. The building is now being used as a retail shop. Photos: NPS files.
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Replace Deteriorated Historic Materials and Features
Following repair in the hierarchy, Rehabilitation
guidance is provided for replacing an entire character-defining
feature with new material because the level of deterioration
or damage of materials precludes repair (for example,
an exterior cornice; an interior staircase; or a complete
porch or storefront). If the essential form and detailing
are still evident so that the physical evidence can
be used to re-establish the feature as an integral part
of the rehabilitation, then its replacement is appropriate.
Like the guidance for repair, the preferred option is
always replacement of the entire feature in kind, that
is, with the same material. Because this approach may
not always be technically or economically feasible,
provisions are made to consider the use of a compatible
substitute material. It should be noted that, while
the National Park Service guidelines recommend the replacement
of an entire character-defining feature that is extensively
deteriorated, they never recommend removal and replacement
with new material of a feature that--although damaged
or deteriorated--could reasonably be repaired and thus
preserved.
Design for the Replacement of Missing Historic Features
When an entire interior or exterior feature is missing
(for example, an entrance, or cast iron facade; or a
principal staircase), it no longer plays a role in physically
defining the historic character of the building unless
it can be accurately recovered in form and detailing
through the process of carefully documenting the historical
appearance. Although accepting the loss is one possibility,
where an important architectural feature is missing,
its replacement is always recommended in the Rehabilitation
guidelines as the first or preferred, course of action.
Thus, if adequate historical, pictorial, and physical
documentation exists so that the feature may be accurately
reproduced, and if it is desirable to re-establish the
feature as part of the building's historical appearance,
then designing and constructing a new feature based
on such information is appropriate. However, a second
acceptable option for the replacement feature is a new
design that is compatible with the remaining character-defining
features of the historic building. The new design should
always take into account the size, scale, and material
of the historic building itself and, most importantly,
should be clearly differentiated so that a false historical
appearance is not created.
Alterations/Additions for the New Use
Some exterior and interior alterations to a historic
building are generally needed to assure its continued
use, but it is most important that such alterations
do not radically change, obscure, or destroy character-defining
spaces, materials, features, or finishes. Alterations
may include providing additional parking space on an
existing historic building site; cutting new entrances
or windows on secondary elevations; inserting an additional
floor; installing an entirely new mechanical system;
or creating an atrium or light well. Alteration may
also include the selective removal of buildings or other
features of the environment or building site that are
intrusive and therefore detract from the overall historic
character. The construction of an exterior addition
to a historic building may seem to be essential for
the new use, but it is emphasized in the Rehabilitation
guidelines that such new additions should be avoided,
if possible, and considered only after it is determined
that those needs cannot be met by altering secondary,
i.e., non character-defining interior spaces. If, after
a thorough evaluation of interior solutions, an exterior
addition is still judged to be the only viable alterative,
it should be designed and constructed to be clearly
differentiated from the historic building and so that
the character-defining features are not radically changed,
obscured, damaged, or destroyed. Additions and alterations
to historic buildings are referenced within specific
sections of the Rehabilitation guidelines such as Site,
Roofs, Structural Systems, etc., but are addressed in
detail in New Additions to Historic Buildings (see nav bar, right).
Energy Efficiency/Accessibility Considerations/Health
and Safety Code Considerations
These sections of the guidance address work done to
meet accessibility requirements and health and safety
code requirements; or retrofitting measures to improve
energy efficiency. Although this work is quite often
an important aspect of Rehabilitation projects, it is
usually not a part of the overall process of protecting
or repairing character-defining features; rather, such
work is assessed for its potential negative impact on
the building's historic character. For this reason,
particular care must be taken not to radically change,
obscure, damage, or destroy character-defining materials
or features in the process of meeting code and energy
requirements.
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