An overlay district is an area that is additionally placed within an existing zoned districts, or superseding multiple borders of existing districts. Types of overlay districts can include for example a commercial or environmental overlay. Another type of overlay zoning is a historic overlay. A historic overlay district can protect certain buildings, monuments and other older structures that have a historical significance for the community. The aim of the historic overlay district is to preserve history, culture, and archeology. (Town of Scottsville, 2011)
As a historic overlay district is placed on top of underlying base zones, it is required to also obey the restrictions and rules of the underlying zone. These already existing rules are additional to the requirements and rules that comes with the historic overlay. In other words: construction work within an area that is located both in a residential and in a historic overlay zone needs to obey the rules of both zones.
The first historic overlay district in the USA was established in Charleston, South Carolina in 1931. The establishment of the historic overlay district lead to the creation of a special board, the Board of Architectural Review (BAR), which can nowadays be found in many cities throughout the USA. The aim of every BAR is to preserve the cultural and historical heritage of the city within the historical zones. Also, the BAR controls all exterior changes, new buildings, and additions to historic buildings and sites located in a historic overlay district. Repair, maintenance, and replacement with similar materials are not subject to review. (Charleston SC).
