Flashing is often the tail that wags the dog in construction. It typically represents less than half of one percent of the cost of a project. However, flashing is one of the most critical building components for the long-term health of a structure.
In recent years, an array of new flashing products have emerged. Some arise out of value engineering; some attempt to take advantage of modern technologies for easier installation; and yet others appeal to aesthetics.
In the late 1700's, Thomas Jefferson designed and installed tin underlayment for the roof of Monticello (his home) as well as the Rotunda building at Center College (now University of Virginia). As President, he insisted on a similar design for the Capitol Building. This product is widely recognized as the first form of flashing.
Modern multi-story construction designs arrived in the late 1800's, most famously from the Chicago School. Cavity walls were introduced, substantially reducing water infiltration into buildings. Parapet walls became code requirements to ward against urban fires spreading from one building to another. Given these changes in design standards, flashing became a necessity.