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Moravian College • Preservation Master Plan
of wood siding is required, the new siding should
match the species of existing wood. This practice
gives the wall a consistent texture and appearance
and avoids problems with expansion rates, which
vary between wood species.
Reconstruction of a missing wood detail or feature
that does not have a salvaged historic prototype
should be guided by historic, physical, and pictorial
evidence for accurate restoration. Reconstruction
of missing elements should be based on historical
evidence and match the appearance of surviving
features in size, scale, material, and color. Do not
replace missing wood features with conjectural
historic reconstructions or contemporary elements
that are incompatible with the building’s style,
character, and other historic features.
Synthetic Materials
A number of buildings at Moravian College have
synthetic cladding applied over wood elements,
including cornices, window frames and sills, and
the few areas of wood siding. The installation of
vinyl or aluminum siding or cladding materials on
historic buildings is not an appropriate preservation
treatment. Synthetic materials seriously alter the
historic appearance and character of a building by
removing or covering important details such as
cornices, window and door trim, and wood siding.
The use of synthetic siding on new construction
within an historic context, such as an addition,
should also be discouraged. It cannot be considered
a compatible treatment.
Synthetic siding materials are not recommended for
historic wood-clad buildings. They should never
be applied over wood nor should they replace
wood siding. Synthetic siding can cause serious
long-term damage to buildings. Foremost among
these is moisture trapped beneath new siding,
which decreases the efficiency of insulation and
accelerates deterioration of structural elements.
Condensation behind the siding and leaks can cause
serious damage to the underlying wood structure.
Related interior consequences include peeling paint
and cracked wall surfaces.
Synthetic siding materials are also problematic
because they are not maintenance-free as frequently
advertised. Colors and finishes fade over time,
synthetic materials crack and warp, and products
are changed or discontinued. The cost of periodic
vinyl or aluminum siding replacement is more
expensive than the cost of maintaining historic
wood.
When properly maintained, historic cladding
materials are durable and serviceable. Properlymaintained
and painted wood siding is the more
structurally and historically sympathetic option.
9.6 Roofs and Drainage
Systems
In terms of protection and preventative
maintenance, roof systems are among the most
important building elements. The roof, composed
of framing, sheathing, flashing, and roofing
materials, and the roof drainage elements should
be approached as one system, since failure in
one component can cause extensive damage and
deterioration elsewhere. Providing a weather-tight
roof and properly functioning drainage system is
critical to historic building preservation and should
be addressed before any other concern.
The roof not only keeps water out of a building’s
interior, it also keeps water from penetrating
structural members and exterior walls. Although
each roofing material requires its own level of
maintenance and repair, the essential function of
any roof is to prevent water infiltration. Roofs are
more, however, than merely the system that protects
the structure and interior of a building from the
elements; they are important and highly-visible
design features. A roof is characterized by its shape,
height, configuration, materials, and decorative
elements, which help define the architectural style
of a building. Since a roof is constantly exposed to
the elements, it will reach a point where partial or
major replacement is necessary. The preservation
approach places emphasis on retention and
repair with any necessary replacements matching
the existing in color, texture, size, and other
visual qualities. All roof components should
receive the same level of preservation; characterdefining
roof elements include roofing materials,
dormers, cupolas, and decorative features such as
weathervanes, finials, and crests.
Roof drainage systems are an important component
of properly functioning roofs. Roof drainage systems
include gutters, scuppers, downspouts, boots,
and underground drains, as well as site drainage
components, such as splash blocks, drainage swales,
French drains, and channel drains. Typically, the
roof is sloped to drain water to a perimeter gutter
John Milner Associates • October 2009 • Chapter 9 • Building Guidelines • 298