Sanborn Keys & Colors

Fire insurance maps are distinctive because of the sophisticated set of symbols that allows complex information to be conveyed clearly. In working with insurance maps, it is important to remember that they were made for a very specific use, and that although they are now valuable for a variety of purposes, the insurance industry dictated the selection of information to be mapped and the way that information was portrayed. Knowledge of the keys and colors is essential to proper interpretation of the information found in fire insurance maps.

Color

Example 1

Color plays an important role in Sanborn map reading. In Example 1, we see that brick and tile are represented with a reddish/pink color. Several advantages demonstrate themselves when using color: a) the mapmaker can easily and quickly convey information; b) space formerly used to convey this information can now be used to convey more detailed information; and c) uniformity across all the maps is achieved and maintained.

Example 2

The use of yellow indicates frame, or wood, structures. Example 2 shows the use of framing on the inside as well as outside of buildings. Along with the color indicators, the map uses basic abbreviations to convey other information. S = store, D = dwelling, and ASB. CL. = asbestos clapboards.

Example 3

Other colors employed by Sanborn mapmakers included an olive green to demark fire resistive construction and gray for adobe construction material. Blue denotes concrete and cinder block construction. Gray is also used to indicate metal or iron building materials. The tenant indicator "loft" is shown in color to indicate that it can be seen in any of the construction color indicators.

Example 4

To print an image with many of the colors and symbols, click here.