Roof Designs

1. 19th century gable roofs sloped to the front and rear with a pitch of 7/12 (seven foot rise for every twelve feet of run) or 8/12.

2. A few rare examples of front/rear sloping gable roofs can be found with roof pitches up to 10/12.

3. Late 19th century (1880-1900) structures had side sloping gable roofs with a pitch of 4/12 to 6/12 and a sloped apron across the front creating a half gable on the front of the building which was treated in a decorative manner.

4. Early 20th century structures had side sloping gable roofs with a pitch of 4/12 to 6/12 with a full front gable.

1. Early examples (18th and early 19th century) usually had rather steep pitches of 12/12 or 11/12 and sometimes canted out (double pitch on each slope) in a West Indies style.

2. Most 19th century examples usually had pitches of 3/12 to 6/12 and were often hidden from view from the street by a parapet wall.

3. Some examples exist of hipped roofs with one side having a gable end, usually occurring at corners or when a shorter building butted up directly to an adjacent taller structure.

1. Pitch usually ranged from 5/12 to 7/12.

2. Examples rarely found on main buildings but used extensively on service buildings and other dependencies.

Dormers were sometimes used on those gabled and hipped roofs which were steep enough to accommodate habitable attic space. The roof plane always remained dominant when dormers were applied. Therefore, the clear roof area must exceed the area penetrated by the dormer(s). A typical dormer is approximately four feet (4') wide, and only one occurs in each approximately twenty feet of roof width.

High standards of renovation or restoration should include all parts of a building and the restoration of dormers is therefore strongly encouraged.

1. Skylight installations should be handled with care and attention to their effect on the appearance of the roof, the roof structure and the compatibility of materials. They should relate primarily to the historic appropriateness of their use and only secondarily to the contemporary needs of the present occupants.

2. Building Types

   1. Skylights may be appropriate on original warehouses and commercial structures.

   2. Skylights are occasionally appropriate on townhouse structures, Creole cottages , Victorian shotguns, and slave quarter structures where dormers do not exist and when the installation meets the criteria under 3) below.

3. Size and Location

   Plans for skylight installation shall meet the following criteria:

   1. Skylights should not be visible from the street and shall be located for the least visibility from any location.

   2. There shall be a minimum number of skylights on a roof, with minimum alteration to original roof structure.

   3. Skylights shall occupy not more than three (3) percent of the roof plane on which they are located.

   4. Long axes of skylights shall be parallel to the rafters.

   5. Skylights shall not be placed on roof slopes with dormers.

4. Design Skylights shall be flat with clear or tinted glazing to give a dark appearance from the exterior. The exposed frame shall be painted or anodized a color to match the roofing material color. Skylights may be operable or fixed.

Buildings that are rehabilitated should have their chimney and chimney tops restored. Chimney tops should be decorative as well as watertight. Chimney pots were of pottery and were used on later buildings. The long axes of chimneys were usually parallel to the side walls and perpendicular to the front walls of buildings. An acceptable rooftop treatment must be provided for all "prefab" metal fireplace flues, which should conceal the flue.

1. Existing slate roofs on all Purple and Blue rated buildings shall be maintained or replaced with slate.

2. Existing slate roofs on all Green and Pink rated buildings shall be maintained or replaced with slate or cement, slate-type shingles.

3. Existing slate roofs on all Yellow, Brown, and Orange rated buildings may be replaced with slate, cement slate-type shingles, Dutch-lap cement shingles, or American traditional shingles.

4. All clay tile roofs shall be maintained or replaced with comparable clay tiles.

5. Pitched roofs without slate or tile:

   1. On all roofs composed of materials other than slate or tile, replacement materials shall be of at least comparable quality to the material replaced, with no building receiving a roof of lesser quality than standing seam painted galvanized iron. Purple and Blue rated buildings shall receive no roof of lower rank than cement, slate-type shingles; Green and Pink rated buildings shall receive no roof of lower rank than Dutch lap cement shingles, unless there is evidence that the original roof was composed of a material other than those permitted.

   2. The ranking of roofing materials is as follows:

      1. Slate

      2. Cement, slate-type shingles

      3. Dutch lap patterns of cement shingles

      4. American Traditional shingles

      5. Standing seam copper

      6. Standing seam painted galvanized metal.

6. Flat Roofs

   Gravel or smooth surface built-up or single-ply roofing is only appropriate for some commercial buildings. Replacement of pitched roofs with flat roofs is strongly discouraged.