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The kinds of stone most commonly encountered on historic buildings in the U.S. include various types of sandstone, limestone, marble, granite, slate and fieldstone. Brick varied considerably in size and quality. Before 1870, brick clays were pressed into molds and were often unevenly fired.

The quality of brick depended on the type of clay available and the brick-making techniques; by the 1870s--with the perfection of an extrusion process--bricks became more uniform and durable. Terra cotta is also a kiln-dried clay product popular from the late 19th century until the 1930s.

The development of the steel-frame office buildings in the early 20th century contributed to the widespread use of architectural terra cotta. Adobe, which consists of sun-dried earthen bricks, was one of the earliest building materials used in the U.S., primarily in the Southwest where it is still popular.

Mortar is used to bond together masonry units. Historic mortar was generally quite soft, consisting primarily of lime and sand with other additives. By the latter part of the 19th century, portland cement was usually added resulting in a more rigid and non-absorbing mortar.

Like historic mortar, early stucco coatings were also heavily lime-based, increasing in hardness with the addition of portland cement in the late 19th century. Concrete has a long history, being variously made of tabby, volcanic ash and, later, of natural hydraulic cements, before the introduction of portland cement in the 1870s.

Since then, concrete has also been used in its precast form. While masonry is among the most durable of historic building materials, it is also very susceptible to damage by improper maintenance or repair techniques and harsh or abrasive cleaning methods.

Wood has played a central role in American building during every period and in every style. Whether as structural members, exterior cladding, roofing, interior finishes, or decorative features, wood is frequently an essential component of historic buildings.

Because it can be easily shaped by sawing, sanding, planing, carving, and gouging, wood is used for architectural features such as clapboard, cornices, brackets, entablatures, shutters, columns and balustrades.

These wooden features, both functional and decorative, are often important in defining the historic character of the building.

Architectural metal features--such as cast iron facades, porches, and steps; sheet metal cornices, siding, roofs, roof cresting and storefronts; and cast or rolled metal doors, window sash, entablatures, and hardware--are often highly decorative and may be important in defining the overall character of historic American buildings.

Metals commonly used in historic buildings include lead, tin, zinc, copper, bronze, brass, iron, steel, and to a lesser extent, nickel alloys, stainless steel and aluminum.

Historic metal building components were often created by highly skilled, local artisans, and by the late 19th century, many of these components were prefabricated and readily available from catalogs in standardized sizes and designs.

Information above was provided by the National Park Service. Future articles will cover standards, practices, regulations, and how to’s. For more on standards log onto: http://www.nps.gov/

Remodeling, restoration, new additions, carports, pergolas, gutters, roofs, signage, and so on within the Blanco Historic District must have a Certificate of Appropriateness issued by the Blanco Historic Commission at the City Hall on Pecan St at the square.

For more information on the City of Blanco ordinance, log onto: http://www.blancoguide.com/

On design guidelines log onto: http://www.blancoguide.com/design/. Design Guidelines help’s the Blanco Historic Preservation Commission (BHPC) with renovation/construction requests in the downtown historic district, which encompasses the 9 blocks that make up the square.

Rudy Nino a local resident is a remodeler-builder member and advisor to the City of Blanco Historic Commission.