stucco

자료: Columbia Encyclopedia

stucco (stŭk'ō) , in architecture, a term loosely applied to various kinds of plasterwork, both exterior and interior. It now commonly refers to a plaster or cement used for the external coating of buildings, most frequently employed in Mediterranean countries. 

It usually consists of a mixture of cement or lime and sand, applied in one or more coats over a rough masonry or frame structure; the finish is either troweled, floated, or rough textured. The finish called roughcast or rock cast, formerly common in England and the United States, consists of small gravel or other pebbles mixed with wet plaster and thrown or dashed forcibly against a freshly plastered wall. In Italy a form of decoration known as graffito is often applied to a stucco wall. In ancient Greece a form of stucco was often used over coarse stonework to give a fine surface suitable for receiving detail. The Romans employed stucco similarly on external surfaces and, with notable success, as an interior finish; for indoor work they used a mixture of plaster of Paris or powdered marble, capable of receiving a high finish. The term stucco is also applied to various forms of interior decoration in relief that more properly would be classified as plastering.

자료: Wikipedia

Stucco or render is a material made of an aggregate, a binder, and water. Stucco is applied wet and hardens to a very dense solid. It is used as a coating for walls and ceilings and for decoration. Stucco may be used to cover less visually appealing construction materials such as concrete, cinder block, or clay brick and adobe.

Stucco from the House of Borujerdi-ha, 1850s, Kashan, Iran.

Contents  [hide] 1 Composition 2 Traditional Stucco 3 Modern stucco 4 See also 5 External links 6 References

Composition

The difference in nomenclature between stucco, plaster, and mortar is based more on use than composition. Until the later part of the nineteenth century, it was common that: 

• plaster, which was used inside a building, and 
• stucco, which was used outside, would consist of the same primary materials: lime and sand (which are also used in mortar). 
  

Animal or plant fibers were often added for additional strength. In the later part of the nineteenth century, Portland cement was added with increasing frequency in an attempt to improve its durability. At the same time, traditionallime plasters were being replaced by gypsum plaster.

Traditional stucco is made of lime, sand, and water. Modern stucco is made of Portland cement, sand, and water. Lime is added to decrease the permeability and increase the workability of modern stucco. Sometimes additives such as acrylics and glass fibers are added to improve the structural properties of the plaster. This is usually done with what is considered a one-coat stucco system, as opposed to the traditional three-coat method.

Lime stucco is a relatively hard material that can be broken or chipped by hand without too much difficulty. The lime itself is usually white; color comes from the aggregate or any added pigments. Lime stucco has the property of being self-healing to a limited degree because of the slight solubility of lime (which in solution can be deposited in cracks. where it solidifies). Portland cement stucco is very hard and brittle and can easily crack if the base on which it is applied is not stable. Typically its color was gray, from the innate color of most Portland cement, but white Portland cement is also used. Today's stucco manufacturers offer a very wide range of colors that can be mixed integrally in the finish coat.

Traditional Stucco

Stucco used as an exterior coating on a residential building.

As a building material, stucco is a durable, attractive, and weather-resistant wall covering. It was traditionally used as both an interior and exterior finish applied in one or two thin layers directly over a solid masonry, brick or stone surface. The finish coat usually contained an integral color and was typically textured for appearance.

Then with the introduction and development of heavy timber and light wood-framed construction methods, stucco was adapted for this new use by adding a reinforcement lattice, or lath, attached to and spanning between the structural supports and by increasing the thickness and number of layers of the total system. The lath added support for the wet plaster and tensile strength to the brittle, cured stucco; while the increased thickness and number of layers helped control cracking.

The traditional application of stucco and lath occurs in three coats — the scratch coat, the brown coat and the finish coat. The two base coats of plaster are either hand-applied or machine sprayed. The finish coat can be troweled smooth, hand-textured, floated to a sand finish or sprayed.