Doors
The retention of original doors is important in the effort to maintain the authentic historic interest of a building in local historic districts. The Commission therefore strongly discourages the removal of original doors from all rated structures under its jurisdiction. Any application to replace a door on a purple or blue-rated structure must be approved by the full Commission. On buildings with lower color ratings (green, red and gold) the staff may review and approve appropriate replacement doors. All applications for replacement doors must be supported by drawings showing the design and size of the proposed replacement units. In some instances the staff of the Commission may accept a photograph of a door as documentation of the unit proposed for installation.
French Doors with Batten Shutters, typical of early 19th century
French Doors.
The most common exterior door type in historic districts, French doors, consists of a pair of doors, each having one or two panels at the bottom and a glazed section at the top. The earlier examples (before 1830) generally had a single bottom panel with many small panes above. Later examples often had two vertical bottom panels and fewer, larger panes above. French doors of various forms were used in buildings of virtually all styles, types and dates, but specific design was (and should be) related to the specific design of the buildings on which they are located.

Six-panel Door in ‘Greek Key' frame, ca. 1850
Paneled Doors.
Most often found on American style houses such as the American townhouse or center hall cottage, solid paneled doors consist of rails and stiles which form a rigid framework; in the spaces between the rails and stiles, wooden panels are held in place by panel moldings. The width of the various rails and stiles, their arrangement, the profiles of panel moldings and panels are all determined by style, type and date. Appropriateness should be respected. Paneled doors are usually hung individually on the exterior. Some single paneled doors are glazed in their upper portion above the lock rail. Early and mid 19th century examples usually had separate glazed sections in each upper panel. Examples of this type are often found on service buildings. Later 19th century examples usually had one large single glazed panel above the lock rail.

Two Types of Store Fronts, ca. 1885
Store Doors.
Store doors are used on commercial buildings. They resemble French doors in that they have a paneled lower portion and are glazed above the lock rail. The difference is that store doors incorporate a night blind or metal grille to cover the glazed portion. Grilles were permanently fixed and were usually reserved for warehouses or similar buildings. Night blinds were removable and were put into place at night and removed when the shop was open. 
Because of the rabbet or groove necessary to hold the night blind, and because doors of this type were often eleven or twelve feet tall, they were often very thick (on the order of 2 1/2"). Smaller doors were sometimes thinner, and details varied slightly because of the reduced thickness. The practice of attempting to simulate the appearance of store doors with night blinds by routing a groove around the glazed portion of conventional French doors is strictly prohibited. Store doors were used on buildings with granite or cast iron pilasters and columns. The doors were usually hung behind the columns with no visible frame and swung inward. The number of doors per opening varied from two (2) to six (6). Multiple doors were hinged onto one another. As store doors were equipped with night blinds, exterior shutters were never used.