B. GUIDELINES TO PRESERVE AND PROTECT HISTORIC BUILDINGS
1. Cleaning Historic Structures
Exterior cleaning of historic structures should
be done in the gentlest way possible. Destructive techniques such as sandblasting
and harsh chemical cleaners are not recommended. High-pressure washing
is not appropriate and can cause damage to structures (Figure
Recommended Cleaning Techniques
Exterior Woodwork (in preparation
Apply 1:4 solution of household chlorine bleach in water to soiled woodwork,
using a natural or plastic-fiber bristle brush or garden bug sprayer.
Scrub using natural or plastic-fiber bristle brush, followed by a water
rinse at a maximum of 1,200 pounds per square inch (psi) of pressure at
24 inches from the wall surface using a 15 degree spray tip.
Brick, stone, and stucco
Water rinse using maximum 600 psi water pressure at 6 inches from masonry
surface using a 15 degree spray tip (or 1,200 psi at 24 inches). For heavily
soiled surfaces, apply a dilute mixture of a specially formulated masonry
cleaner according to the manufacturers instructions. After the specified
contact time, scrub masonry using natural or plastic-bristle brush, followed
by maximum 600 psi water rinse. Never use muriatic acid on historic brick
masonry. Do not use acidic or caustic cleaners that will etch glass, damage
paint finishes, or pose environmental risks.
2. Historic Masonry
Historic masonry requires particular maintenance to be preserved. Although
brick units themselves have a long life, mortar joints deteriorate over
time and require periodic renewal. Where repointing is required, care
should be taken to ensure that the brick is not damaged in the process
of removing deteriorated pointing. The new mortar should match the color,
texture, and tooling of the original mortar, not the appearance of the
surface dirt on weathered pointing (Figure
36). Unless the existing joint profile is a scribed profile, the new
pointing should be slightly recessed, struck flat. Deeply struck (recessed)
and concave joint profiles are generally not appropriate. The slight recess
is important, however, to prevent the mortar from smearing onto the face
of the bricks, resulting in an enlarged joint width which is both unsightly
and historically inappropriate. New pointing should not have a high Portland
cement content. Mortars rich in Portland cement are harder and less permeable
than historic masonry units, causing damage to the brick or stone. Recommended
historic mortars for historic West Chester masonry include the following:
Historic Wall Brick:
1 part by volume white Portland cement
2 parts by volume hydrated lime
6 parts by volume selected sand.
Historic Chimney Brick:
1 part by volume white Portland cement
1 part by volume hydrated lime
5 parts by volume selected sand
2.2 Paint Removal.
Generally, the complete removal of paint from historic masonry is not
appropriate. If, during a restoration project, an owner desires to remove
paint from brick walls, a spot test should be conducted to assess the
condition of the original brickwork below. If the building has been painted
for several decades, an owner may elect to repaint the structure. Prior
to undertaking paint-stripping operations, a test panel must be conducted
to make sure the brickwork is not damaged during the cleaning process.
Dry-grit blast cleaning (sandblasting) is never recommended, because it
causes irreversible damage to historic masonry surfaces.
3. Stucco (Cement/Lime Plaster)
Stucco should not be applied over historic materials.
The removal of stucco to expose original historic masonry is acceptable.
However, some stone structures were originally roughly laid and covered
with a cement/lime plaster. In this case, the cement/lime plaster should
not be removed, but rather preserved or restored. A test panel should
be prepared to determine the feasibility and appropriateness of removing
exterior stucco. Great care should be taken in removing stucco so as not
to damage the historic fabric.
3.1 Simulated Brick and
Simulated brick and stone facings have been applied to a small number
of brick buildings in the Historic District. Typically these Portland
cement plaster facings were applied when aggressive salesmen convinced
building owners that the cost of the facing would be less than the cost
of repointing and maintaining a brick facade over time. Existing facings
should be maintained and painted brick red. Where the facing is deteriorated,
a test panel should be prepared to determine the feasibility and appropriateness
of removing it. Because of the strong adhesion of the Portland cement,
removing the facing may not be economically feasible. Great care should
be taken in removing the simulated brick facing so as not to damage the
historic brick substrate.
4. Exterior Colors and Color
Exterior colors and color schemes should be appropriate
to the architectural style and period of the building. Paint analysis
and historic documentation are encouraged for the owner who desires specific
color information about a historic structure, but it is not mandatory.
Certain paint manufacturers offer historically accurate exterior paint
colors, including specific palettes for different architectural styles.
Refer to the bibliography (appendix E) for
published references relating to appropriate historic colors and color
In most cases, color schemes can be organized according
to the body, major trim, minor trim, and shutter colors (Figure
37). The body color covers wall surfaces, and on commercial buildings
includes any storefront piers. In some cases, the body color will be natural
brick or stone and will not require painting. Major trim includes the
cornice, window frames, decorative window crowns, storefront cornices,
storefront columns, and bulkheads. Minor trim consists of window sashes,
doors, and storefront frames. Shutters are typically painted yet another
While early nineteenth-century buildings historically
featured simple color schemes brick walls, white exterior woodwork,
and dark green shutters and front door, for example later Victorian
styles featured color schemes which might include several colors. However,
overly elaborate color schemes, and all color schemes employing multiple
pastel colors, are not appropriate. The so-called painted ladies
are based on popular images of Victorian architecture, not on history.
When a historic building is repainted, the removal of all paint layers
to bare wood is not recommended. Except for heavily weathered paint, scraping
off loose material in preparation for new coats of paint is sufficient.
Unpainted brick surfaces generally should not be painted. Painted brick
surfaces should remain painted. In some instances, paint may be removed
from brick, but typically it is not recommended (See
B.2.2 - Paint Removal).
On commercial buildings, the paint scheme for the entire
building should be coordinated, including building cornice, upper-floor
windows and shutters, storefront, and doors. Storefronts should not be
repainted without taking into account the color scheme and condition of
paint on the entire facade. Finally, historically unpainted metals, such
as brass storefront framing or hardware, should not be painted.
5. Historic Roofing Systems
Significant historic roofing materials and features
that are visible from the street should be preserved. Efforts should be
made to retain and repair original roofing that is visible from the street.
Where the material is too deteriorated and replacement is necessary, new
roofing materials should replicate the original roofing material used
on the historic building. Building owners are encouraged to conduct an
investigation to determine the original roofing materials, either by means
of looking at historical photographs or by physical examination of the
roof sheathing by a knowledgeable roofer. Typical historic roofing used
on sloping roofs in the West Chester Historic District was standing-seam
metal or slate shingles.
Flat roofs are not addressed in these Design Guidelines,
and no Certificate of Appropriateness is required to obtain a building
permit for the replacement of a flat roof.
5.1 Slate Shingle Roofing.
Slate shingle roofing replaced wood shingle roofing in large cities because
slate was fireproof. In rural areas, slate shingle roofing was also desired
for its durability, and in the late nineteenth century for its decorative
The continued maintenance of existing slate roofing is
highly encouraged and less expensive than replacement with a substitute
material. The replacement of severely deteriorated historic slate roofing
with new slate roofing is also highly encouraged. On buildings with Mansart
roofs, the replacement of slate with standard asphalt shingles is not
39). On buildings with gable or hipped roofs, replacement of slate
with asphalt shingles is discouraged but acceptable (See
B.5.4 - Asphalt Shingles).
5.2 Metal Roofing.
The continued maintenance of existing metal roofing is highly encouraged.
The replacement of severely deteriorated metal roofing with new metal
roofing is also highly encouraged. Traditional standing-seam metal roofing,
painted, is encouraged for re-roofing projects and new roofs (Figure
40). However, pre-formed standing-seam roofing which utilizes low
profile (1 inch height) seams may also be acceptable.
5.3 Substitute Materials.
Substitute materials that closely replicate historic roofing are acceptable.
For example, recycled rubber/polymer shingles or fiber-reinforced cement
shingles that resemble slate cost less than a natural slate roof but visually
5.4 Asphalt Shingles.
Asphalt shingle roofing is not recommended on roof slopes that are visible.
If asphalt shingles are proposed for a visible roof, it is recommended
that the shingles be heavyweight, dimensional shingles that resemble historic
materials. A color similar to the historic roofing material is recommended.
White and light green asphalt shingle roofing, for example, cannot be
appropriate, because slate in these colors is not found in nature.
The prominence of the roof
and the height and angle of the roof as seen by a pedestrian will be factors
that the HARB will consider in its evaluation of each individual roof
replacement proposal (Figure
41). The roofing material used on a sloping porch roof or storefront
cornice is near to the viewer and, therefore, visually very important.
In contrast, a shallow pitch, say 3-in-12 slope, gable roof on a three-story
commercial building is simply not visible from the sidewalk and, therefore,
not visually important. However, on a building with a Mansart roof, as
much as one-third of the visible face of the building is the roofing material.
To replace the slate shingles on a Mansart roof with asphalt shingles
would be analogous to replacing a brick facade with vinyl siding.
5.5 Gutters and Downspouts.
When hung gutters and downspouts are replaced, the use of half-round gutters
and smooth round downspouts is historically appropriate and thus recommended
for historic buildings (Figure
42). New copper, terne-coated stainless steel, and lead-coated copper
gutters and downspouts may be allowed to weather naturally, but aluminum
and galvanized steel gutters, downspouts, and leader boxes should be painted
to blend in with the color of the building to reduce their visibility.
Vinyl gutters and downspouts are not appropriate.
Built-in gutters and pole gutters (water diverters) are
often found on historic buildings (Figure
43). These forms of gutters collect roof water without the visual
intrusion of an exposed metal gutter at the cornice line. The continued
maintenance of built-in gutters and pole gutters is highly encouraged.
The in-kind replacement of severely deteriorated built-in gutters and
pole gutters is also highly encouraged.
6. Preserving Historic Roof
Significant historic roof features such as cornices,
cupolas, and dormers should be preserved or restored (See
Figure 39). Removing or obscuring any of these features is not appropriate.
Historic chimneys are significant features of a structures architectural
character. A replacement chimney should be an accurate reproduction of
an original chimney and based on physical or pictorial evidence (Figure
44). Where an interior chimney is removed as part of a proposed alteration,
the exterior portion of the chimney should be preserved or reconstructed
to retain the historical appearance of the structure. (Caution: if the
interior chimney has been removed, the chimney above the roof must be
properly braced to support the imposed load!)
6.2 Dormers and Cupolas.
Examples of significant historic gable, hipped, segmental arch-head, and
shed dormers exist in the West Chester Historic District (Figure
45). The construction of new dormers or a cupola on any principal
facade is not appropriate. If physical and pictorial evidence proves that
either of these features originally existed, the reconstruction of the
original feature is encouraged. New dormers are permissible only on secondary
facades. New shed, gable, and segmental-arch dormers should be compatible
in size, scale, and proportion with the original facade, and their placement
should relate vertically to the buildings fenestration (Figure
46). The overall width of dormers should be no wider than one-half
the overall roof width (Figure
The installation of skylights on a principal facade is not appropriate.
Skylights may be installed on secondary facades. Skylights should be low-profile,
flat-glazed construction, and mounted close to the roof. Careful consideration
should be given to the placement of skylights. Skylights should relate
vertically to the overall fenestration of the facade (Figure
7. Mechanical, Electrical,
and Communications Equipment
The installation of television antennas, security
cameras, satellite dishes, outdoor air-conditioning equipment, exhaust
fans, and other mechanical, electrical, and communications equipments
on principal facades is not appropriate. Equipment should be situated
so it is not readily visible from a public way. Air-conditioning equipment
may not be mounted on sloping roofs. On flat roofs, air-conditioning equipment
should be screened from view by vertical board or other acceptable screening.
8. Wall Siding and Trim
While most buildings in the West Chester Historic
District are brick masonry, some additions and out-buildings are wood-frame
construction. Siding should be appropriate to the building. In West Chester,
wood siding is typically horizontal clapboarding (Figure
49), either a beveled profile or a drop-siding profile (German
siding). The visual character created by the texture and pattern
of historic siding should not be altered by its replacement with different
siding profiles or non-historic siding materials. In the Historic District,
vinyl and aluminum siding are not appropriate substitute materials except
on secondary facades. The removal of existing synthetic siding and its
replacement with historically appropriate siding is encouraged. Wood trim
elements such as corner boards, window and door surrounds, brackets, moldings,
and other decorative features should also be repaired or replaced to match
their historic appearance.
The cladding (wrapping) of exterior woodwork such as
cornices, corner boards, fascias, projecting bays, brackets, window and
door frames, porch framing and trim, and other exterior woodwork with
aluminum or vinyl materials is not appropriate. Not only does the cladding
cover historic wood moldings and architectural detail, but it also causes
the covered woodwork to deteriorate because of moisture that becomes entrapped
under the sheet metal.
Copyright © Frens and Frens, LLC 2002.
Visit the 'About this Site' page for other information.
the 'Acknowledgements' page for other important notes about contributions
to this project.