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Stone veneer is a thin layer of any stone used as decorative facing material that is not meant to be load bearing. Stone cladding is a stone veneer, or simulated stone, applied to a building or other structure made of a material other than stone. Stone cladding is sometimes applied to concrete and steel buildings as part of their original architectural design.


History

Thin stone veneer was first developed in the late 19th century, but there were materials developed much earlier that foreshadowed its use. For instance, the ancient Romans built large structures out of
Roman concrete Roman concrete, also called , is a material that was used in construction in ancient Rome. Roman concrete was based on a hydraulic-setting cement. It is durable due to its incorporation of pozzolanic ash, which prevents cracks from spreading. By ...
, and sometimes used a form of stone veneer to face them. Parts of the Roman Coliseum were originally faced with marble veneer; the holes which once held the anchors for the veneer are still visible. Modern stone veneer first made its appearance in the late 1800s. The oldest of modern stone veneer product is now disintegrating. It was cut into thick portions and then hand tooled into the appropriate panels; the stones that were used were "granite, marble, travertine, limestone, and slate." Early in its development, thin stone veneer only had the capabilities to be utilized in areas such as the inside of buildings, street-level facades and storefronts. In the Late 19th and early 20th centuries non-load-bearing stone veneers were regularly affixed to
load-bearing wall A load-bearing wall or bearing wall is a wall that is an active structural element of a building, which holds the weight of the elements above it, by conducting its weight to a foundation structure below it. Load-bearing walls are one of the ea ...
s behind. As buildings began to grow taller with the advent of skeletal
steel framing Steel frame is a building technique with a "skeleton frame" of vertical steel columns and horizontal I-beams, constructed in a rectangular grid to support the floors, roof and walls of a building which are all attached to the frame. The developm ...
, it became necessary to diminish the thickness and weight of masonry walls in order to withstand the dead weight of the building. Without steel supports, load bearing walls could grow several meters thick on their lowest stories. A solution employed in the construction of early skyscrapers was the use of a steel structural frame that supported exterior stone walls at every floor, thereby distributing the load into the frame. This avoided a gradual buildup of weight that resulted in inconveniently thick lower walls.https://books.google.com/books/about/Historic_building_fa%C3%A7ades.html?id=j-tSAAAAMAAJ , Historic Building Facades William G. Foulks Preservation Press. The
Empire State Building The Empire State Building is a 102-story Art Deco skyscraper in Midtown Manhattan, New York City. The building was designed by Shreve, Lamb & Harmon and built from 1930 to 1931. Its name is derived from "Empire State", the nickname of the st ...
uses this method, having two steel beams for attaching stone veneer on each floor; one inside to bear weight, and one acting as a shelf outside to support the building's limestone veneer. One-and-a-half inches became the common thickness of stone veneer in the 1930s. The utilization of thin stone veneer for complete facades of buildings popped up in the 1940s. Stone veneer construction became much of what we see today in the 1950s. Transportation improved, so stone veneer was transported more efficiently and at lower costs than ever before. Methods to attach veneer to steel were developed; diamond-bladed tools became popular for developing thin stone veneer, while elastomeric sealant began to replace mortar techniques in the construction process. Thin stone veneer in the 1960s became more of a standardized look – in fact, standard education on stone veneer became available in ''The Marble Engineering Handbook and Marble-Faced Precast Panels'', which were published by the ''Marble Institute of America and National Association of Marble Producers.'' As stone veneer panels got thinner in the 1960s, the properties of the stone used became more important in order to compensate (as did safety considerations). Concrete as an aid to stone veneer continued to develop, as "in order to eliminate bowing, cracking, and staining of the veneer." "Diamond-studded cables" were used to cut Italian marble into the necessary slabs as a part of an era of specialization in the 1970s. A 1976 patent shows that the stone material of composite stone veneer could be finished and developed in such a fashion that "it does not have the appearance of being a part of a composite stone veneered product.", page 3. The stone veneer was able to be cut to a thickness of in the 1980s because of improvements in technology. The thickness of typical thin stone veneer was three centimeters by the early 2000s. Anchors of support were provided by a specific type of stainless steel or "of aluminum with a non-corroding material separator between the metal and stone." These anchors are attached to the back of the panels with a rod.


Systems

There are a variety of systems for attaching stone veneers to facades including dowel, kerf, and undercut anchoring systems as well as direct fixing. The direct or adhered fixing system relies on a mortar or cement bonding between the substrate wall and the backside of the stone veneer. This application is generally used indoors as exterior weathering and temperature extremes cause the veneer to crack and
spall Spall are fragments of a material that are broken off a larger solid body. It can be produced by a variety of mechanisms, including as a result of projectile impact, corrosion, weathering, cavitation, or excessive rolling pressure (as in a ball ...
. The complete connection between the veneer and substrate does not account for differing rates of thermal expansion between materials, causing them to bind under pressure. Most exterior veneer systems hang stone from a support wall by pins and anchors allowing air space between, essentially using stone as a
rain screen A rainscreen is an exterior wall detail where the siding (wall cladding) stands off from the moisture- resistant surface of an air/water barrier applied to the sheathing to create a capillary break and to allow drainage and evaporation. The ''rai ...
. Anchorage systems are superior for exterior use because they permit any water that permeates the veneer to escape, while air space allows the materials of the supporting substrate wall to expand and contract at different rates to those of the veneer. The
dowel A dowel is a cylindrical rod, usually made of wood, plastic, or metal. In its original manufactured form, a dowel is called a ''dowel rod''. Dowel rods are often cut into short lengths called dowel pins. Dowels are commonly used as structural r ...
anchorage system is one such method of hanging veneer. The system relies on holes drilled into the edges of stone panels in which metal dowels are inserted. The dowels are connected to an
angle bracket A bracket is either of two tall fore- or back-facing punctuation marks commonly used to isolate a segment of text or data from its surroundings. Typically deployed in symmetric pairs, an individual bracket may be identified as a 'left' or 'r ...
that is in turn connected by
anchor bolt Anchor bolts are used to connect structural and non-structural elements to concrete.. The connection can be made by a variety of different components: anchor bolts (also named fasteners), steel plates, or stiffeners. Anchor bolts transfer diff ...
s to the building's load-bearing wall or steel frame. Kerf anchorage systems operate in much the same way with different metal hardware. The kerf system uses grooves cut into the edges of stone veneer panels in which kerf plates or cleats are inserted, those plates are mounted to the wall behind and act much like a shelf on which the stone panel rests. Both the dowel and Kerf anchorage systems can be attached to the top, bottom and sides of each panel ensuring a secure hold and binding the panels together to make a complete veneer. A fourth and somewhat less common anchoring system is the Undercut anchoring system which uses an expansion ring on the end of a bolt to lock into an undercut hole in the back of a veneer panel. Pressure from tightening the bolt causes the expansion ring to flare out, filling the undercut hole. The bolt is then affixed to anchorage system connected to the supporting wall behind.


Materials

Stone veneer can be made from natural stone as well as manufactured stone. Natural stone veneer is made from real stone that is either collected, i.e.
fieldstone Fieldstone is a naturally occurring type of stone, which lies at or near the surface of the Earth. Fieldstone is a nuisance for farmers seeking to expand their land under cultivation, but at some point it began to be used as a construction mate ...
, or quarried. The stone is cut to a consistent thickness and weight for use as a veneer.


Manufactured products

Manufactured stone veneer is fabricated by pouring a lightweight concrete mix into rubber forms and painted with a coloring process which makes it resemble real stone. The stone veneer produced is then attached to walls with special mortars.
Flexible stone veneer Flexible stone veneer is a veneer with a layer of stone 1 to 5 mm thick. Flexible stone veneers should not be confused with traditional stone veneer. It is used for both interior and exterior and especially where bending to a curved surface ...
is fabricated by pulling a thin layer of stone from a slab of slate, sandstone, or mica schist. It is backed by a composite material.


Cladding

Stone cladding often consists of a lightweight simulated stone products with a concrete-type base. These stone cladding products are often fitted to lightweight substrates to reduce the material cost of construction; this would typically comprise * timber stud frame * waterproof barrier * fibre cement sheet * expanded metal mesh * mortar scratch coat. Then, using a mortar mix, the stone cladding would be affixed to the wall. In the USA, a typical installation on a lightweight substrate would use plywood backing as an alternative to fibre cement sheet. Alternatively, stone cladding can be a natural stone that has been quarried and then cut into thin pieces to reduce weight. Being heavier, natural stone cladding often needs mechanical fixing to be adhered to substrates. Mechanical fixing could be using shelf angles, or perhaps a product called stone clip. Several methods or systems are available for installing stone on the exterior of buildings.


See also

*
Ashlar Ashlar () is finely dressed (cut, worked) stone, either an individual stone that has been worked until squared, or a structure built from such stones. Ashlar is the finest stone masonry unit, generally rectangular cuboid, mentioned by Vitruv ...
— solid and clad/veneered stone wall style * Masonry veneer *
Pebbledash Roughcast or pebbledash is a coarse plaster surface used on outside walls that consists of lime and sometimes cement mixed with sand, small gravel and often pebbles or shells. The materials are mixed into a slurry and are then thrown at the wor ...
— exterior decorative veneer * Wythe, a section of masonry


References

{{DEFAULTSORT:Veneer, stone *S Stonemasonry Types of wall Wallcoverings Industrial minerals