Design Guidelines for the West Chester Historic District, Borough of West Chester, Pennsylvania

C. GUIDELINES FOR NEW CONSTRUCTION

The following guidelines pertain to new construction in the West Chester Historic District. New construction includes additions to historic buildings, new structures along primary streets, and secondary structures such as garages, sheds, outbuildings, or workshops.

1. Visual Relationship Between the Old and New
A new building or addition should relate visually to neighboring contributing historic buildings. Proposals for new designs within the Historic District will be considered for their specific location and will be evaluated based on their compatibility with neighboring historic structures. For a typical building, neighboring historic structures include those to each side of the structure and those directly across the street from the structure. For a new building located at a corner, the neighboring historic structures include all buildings at the intersection in addition to those immediately adjacent. Where a building falls near the edge of the Historic District, historic buildings located near but outside of the district will also be taken into account during the review process.

The most successful new buildings in historic districts are ones that are clearly modern in design but compatible with and sensitive to the character of the Historic District. The experience of the Historic District is enriched by new buildings that have merit on their own and are sensitive to their setting.

2. Scale and Massing of Large Buildings
Large buildings should be designed as a series of masses or building elements compatible with the immediate streetscape. The massing or volumetric shape of a building greatly affects the scale of a building and underlies all other architectural features. The typical commercial building in downtown West Chester is a three-bay, three-story brick block with a flat (low slope) roof. Where a large building in the Historic District is unavoidable, the mass of the proposed structure can be broken down into traditional building blocks that relate to the scale of the streetscape, thereby blending into its context (Figure 66).

3. Replicating Historic Buildings
The design of a new building should not be an exact replica of any existing historic building within the district. Copies of historic buildings among original ones look awkward and present a false historic context. However, a new structure’s design may be inspired by historic building designs and features, and may be traditional in form and detailing.

4. Relationship of Additions to Historic Buildings
A proposed addition to a building in the Historic District should be subordinate to the principal facade and mass of the historic building. The subordinate appearance of an addition can be achieved through its setback (See C.5 - Building Placement and Setbacks) massing, width, and detail (Figure 67). The width of an addition should generally not exceed two-thirds the width of the principal historic structure.

5. Building Placement and Setbacks

5.1 Setbacks for New Construction.
Historically, the building type dictated the structure’s setback from the street. Commercial buildings such as taverns, inns, retail shops, and stores fronted directly onto the sidewalk. Structures constructed solely as residences were sometimes set back from the edge of the sidewalk to create a small area of landscaping, but often were built directly on the sidewalk. New construction in the district should follow the precedent of adjacent lots (See C.1 - Visual Relationship Between the Old and New).

5.2 Setbacks for Additions.
Historically, most additions to buildings in the Historic District were built at the building rear facade because there was no available building lot area on the street facade. These additions were often built up to the side yard lot lines, and had minimal visual impact on the appearance of the downtown. When an addition fronted a commercial street, it was typically set flush with the existing building to create the appearance of a larger, more substantial building. Proposed additions should follow the pattern of setbacks of adjacent buildings and building additions in order to blend into the development pattern of the immediate neighborhood.

5.3 Setbacks for Secondary Structures.
Garages, sheds, outbuildings, or workshops should be placed behind and remain visually secondary to the principal building on the lot. Side and rear setbacks should follow the general pattern of the placement of outbuildings in the immediate neighborhood.

6. Building Height and Form

6.1 Additions.
The cornice line on the principal facade of an addition should be equal to or lower than the cornice line on the principal facade of the historic structure. Likewise, the ridge line of an addition should be equal to or lower than the ridge line of the historic structure. The form of new buildings should be compatible with the form of adjacent historic structures (Figure 68).

6.2 New Construction.
The eave line and ridge line of a proposed new principal structure should not exceed the height of the eave line and ridge line of flanking historic structures. The height and overall size of any proposed new secondary structure should not exceed the height and overall size of the principal historic structure on the lot where it is to be constructed.

7. Building Width and Rhythm
Historically, the principal structures of the district fill most if not all the total frontage width along the street. Additions and new buildings should repeat the pattern of filling most of the street frontage of a single lot.

8. Relationship of the Facade Parts to the Whole
All parts of a new building facade should be visually integrated as a composition, which should relate to adjacent buildings (Figure 69). The size and proportions of facade elements such as doors, windows, cornices, and water tables emphasize the vertical and horizontal dimensions of a facade. Exaggeration of these elements and the use of ribbon windows, vertical stacks of windows, and brick courses of contrasting colors create a design that is not compatible and out of proportion with historic buildings.

9. Roof Form, Materials, and Features

9.1 Form.
While most commercial buildings within the district have flat or shed roofs, many buildings feature other roof forms.

Additions: Historically, the roof form of an addition placed along side an existing structure facing a street followed the form of the principal building (see Figure 68). Continuing the historical precedent, additions to gable roof structures that face a street should also have a gable roof. Additions on a secondary facade can have a different roof form, such as a shed roof. Mansart roofs should be utilized in additions only when the existing building features a mansart roof.

New Buildings: On new buildings, the use of one of the historic roof forms found in the district is recommended. Contemporary Mansart roof forms and materials, which have been overused in fast-food restaurants and strip shopping centers, are not appropriate to the Historic District.

9.2 Materials.
Additions: The roofing material on an addition should match the original structure or be visually similar to the existing roofing. For example, an addition to a building with a slate roof should have a roof that is slate, a synthetic slate, or a material that appears similar in color and dimension to slate. The roofing material of a one-story shed addition to a two-story slate-roof house, however, could be another historically appropriate material such as painted metal, especially if the slope of the proposed shed roof is less than that of the main roof.

New construction: The use of traditional roofing materials such as slate and standing-seam metal is encouraged on new buildings. Recycled rubber polymer shingles or fiber-reinforced cement shingles that closely resemble slate and modern historic-looking standing-seam roofing with interlocking pans and low-profile standing seams are available. (Note: Many pre-formed metal roofing systems, however, have clumsy seam and termination details which are not appropriate in the Historic District.) If asphalt shingles are to be used, heavyweight, dimensional shingles in a color similar to those of historic materials are strongly recommended. Membrane roofing is acceptable on flat roofs.

9.3 Features.
Dormers: Dormer design, proportions, and placement on additions and new buildings should be compatible in size, scale, proportion, placement, and detail with the historic gable, hipped, segmental arch-head dormers, and shed dormers found in the Historic District (See Figures 45, 46, and 47). Shed dormers on principal facades are strongly discouraged, and are not appropriate on roof slopes which directly front a street. The overall width of the dormers should be no wider than one-half the overall roof width.

Skylights: Skylights with a low profile are acceptable on all secondary facades but not on principal facades. It is recommended that the placement of skylights relate to the overall fenestration of the building by relating vertically to other openings in the wall (See Figure 48). The use of dormers and skylights on the same roof plane (i.e., next to each other) is not recommended.

10. Exterior Wall Materials

10.1 Additions.
An addition should either replicate the existing exterior wall material in type, color, and texture or be constructed of a historic exterior wall material found in the district. If wood siding is proposed for the addition, the width, type, and detail of the new siding should complement the proportions and scale of the existing building. Cement/fiber synthetic clapboard siding that is manufactured with a smooth surface and field painted is also acceptable on primary facades. The wall materials of an addition should be compatible with the wall materials of the existing building. Except on secondary facades, vinyl and aluminum siding are not appropriate in the district. Except on secondary facades, stucco finishes are not appropriate to the district.

10.2 New Construction.
The use of historic exterior wall materials such as brick, cut stone, or wood siding and their related details are strongly encouraged for new construction. Cement/fiber synthetic clapboard siding that is manufactured with a smooth surface and field painted is also acceptable on primary facades. The use of vinyl or aluminum siding is not recommended except on secondary facades. Likewise, vinyl and aluminum facings and fabricated plastic building components are not appropriate on primary facades.

The size and type of siding materials should be compatible with the building type of the proposed new building. For example, a garage or workshop on an alley may have vertical wood siding such as board-and-batten siding, or may be stucco-faced masonry. A principal structure in the district historically would not have vertical wood siding nor stucco siding, but rather would have been sided with a horizontal wood siding such as clapboards, or would have been constructed of brick masonry.

11. Windows and Doors

11.1 Additions.
It is recommended that the material of windows and doors in additions match the material of the window and doors in the historic structure. The proportion of windows and doors in an addition should be similar to the proportion of original openings in the existing building. Replicating the sash type and pane configuration of the historic windows is encouraged. If the sash type and configuration is not replicated, a sash type and configuration that is compatible in type to the historic sash pattern is recommended. For example, an addition to a three-bay townhouse should either replicate the historic one-over-one, double-hung sash configuration or at least receive a double-hung sash configuration with similar dimensions to the historic fenestration. Sliding glass doors with large uninterrupted sheets of glass are not appropriate on the principal facade of an addition.

11.2 New Construction.
The placement and proportion of windows and doors should relate to the placement and proportion of openings on the historic buildings of the district. It is recommended that vertically proportioned windows placed in a three, four, or five-bay configuration be installed on principal facades. The percentage of window openings to total wall surface on a principal facade should not exceed 33 percent (one-third) of the total wall area (Figure 70). The use of double-hung sash windows is encouraged. On secondary structures, the size and type of windows and doors should relate to the type of structure proposed.

12. Shutters and Blinds
Shutters and blinds are generally discouraged on additions and on new buildings. If shutter or blinds are proposed, they should follow the historical precedent of original shutters and blinds. New shutters and blinds should be properly sized to fit the opening, and should appear operable by being mounted on proper shutter hardware. Plastic or metal shutters and blinds are not appropriate. New shutters and blinds should be fitted with traditional shutter hardware and should not be surface-mounted directly onto an exterior wall surface (See B.11 - Shutters and Blinds).

13. Porches and Stoops
New porches and stoops are encouraged on streets where porches and stoops are common. On additions, porches or stoops should be simple in design and visually relate to the existing building. On new structures, porches or stoops should visually relate to the proposed building in a manner similar to the relationship of historic porches to existing historic buildings in the district.

14. Building Accessibility

14.1 Additions.
Where possible, a building addition should be designed to include features that make up for any accessibility deficiencies of the original building. This approach can eliminate the need for intrusive alterations to the original building (Figure 71).

14.2 New Construction.
All new buildings except private homes and churches are required by law to be accessible to persons with disabilities. New buildings in the Historic District should be designed with integral accessibility features, so that changes in level are accommodated within the new building, not at the building exterior.

15. Hardware, Mechanical,and Electrical Devices
The mounting of small louvers, registers, exhaust fans, alarm devices, cable boxes, utility meters, communications equipment, and other mechanical and/or electrical devices should be avoided on principal facades. To minimize their visual impact, devices mounted on secondary facades should either be painted to match the color of the material on which they are mounted or screened by landscaping features. Air conditioning condenser units should be screened from public view (Figure 72).

16. Lighting
Exterior lighting of additions and new buildings should be simple and in scale with the building. New fixtures should be simple, unobtrusive, and mounted in a traditional manner. Exterior recessed downlights, if proposed, should be placed to avoid dramatic light patterns on the proposed building facade.

17. Relationship of New Outbuildings to Their Historic Context
New outbuildings should visually relate to their historic context (Figure 73). Outbuildings should be simple in design, and should relate to the period of construction of the principal building on the lot. The design of outbuildings should not be overly elaborate. Depending on the placement of the building lot on the street, a proposed outbuilding will be treated as either a primary or secondary facade.