Sidebar: Stone and Glass in a Landmark Library
Sidebar: HUD Standards for Stone Veneer
An increasing number of architects and designers today are specifying manufactured stone veneer for their projects, for a myriad of reasons. As awareness of this innovative material and its benefits grows, so does its use in new and creative applications.
Stone veneers are a value-engineered alternative to natural stone and brick. They are produced from a lightweight concrete mix consisting of Portland cement, lightweight aggregates, admixtures, and mineral oxide colors. The veneers are pre-cast in various sizes in sophisticated molds made from actual stone, resulting in a final product with forms, textures and colors that rival the real thing.
But the ability to deliver the same aesthetic impact of stone and brick is just part of why use is increasing in construction and interior design; stone veneers also do the job at a fraction of the cost—generally just one-third to one-half that of natural stone—and are much easier to handle and install.
Natural stone, for instance, may require wall ties and footings, which increase installation costs. Stone veneer is much lighter and can adhere easily to a variety of structurally sound surfaces, hanging freely without requiring a bottom ledge detail for structural support. This gives designers much greater flexibility in where and how the material can be used—including on soaring walls and in upper levels.
Compared to natural stone’s 10-plus percent waste factor, stone veneer is very efficient (only about 2 percent waste). Manufacturers may incorporate up to 25 percent fly ash—a byproduct of coal burning—into their stone mixes. The use of reclaimed water and post-consumer recyclables such as plastics, glass and wood can also be incorporated, offering incentives for designers interested in LEED® certification.
Bringing the Outside In
Manufactured stone is being used in a wide variety of exterior and interior applications, including fireplaces, entryways, accent walls and other uses where clients want the look of natural stone. The timeless, ageless look of stone as a design element offers a highly textural look and feel that adds warmth and beauty to any space. Old World, contemporary, country or urban, the use of manufactured stone is growing in popularity because of its accessibility, ease of installation and affordability.
Use in commercial interiors has also grown significantly, according to recent studies. Just as stone veneer manufacturers are incorporating more “green” methods and materials, specifiers are also finding stone veneer an eco-friendly choice.
In many cases, designers and consumers are also looking to match native stone from their regions. From an aesthetic standpoint, manufactured stone has reached a point where even the most discerning eye has difficulty recognizing the difference between natural stone and manufactured stone.
World-Class Wine—and Design—in California
Vina Robles Winery is located in the heart of the Paso Robles wine country, halfway between Los Angeles and San Francisco. The 14,000-square-foot Hospitality Center was designed to include several distinctive and highly functional areas, including a retail store, tasting room and various spaces for entertaining. The facility combines classic California Mission-style with modern European elegance.
Tim Woodle, of the design firm of Steven D. Pults, AIA & Associates, San Luis Obispo, CA, headed up a project at the Vina Robles Hospitality Center. Woodle is the principal architect in charge of winery design.
"The area where Vina Robles is located has garnered international attention as an emerging region of world-class wines," says Woodle. "Our clients, Vina Robles of Switzerland, desired a landmark building, with ties to the history of the region—contemporary, and at the same time with a historic permanence in architectural character."
Woodle states that the stone veneer that was used in the Hospitality Center greatly complemented the project. "Stone veneer is one of the ‘statement’ materials for this project, and is used liberally both inside and for the exterior," he says. "Stone was chosen in particular to achieve the aesthetic goals of permanence, and to tie to materials historically utilized within the region. It remains our opinion that the use of stone on this particular structure is one of the key, defining features in the aesthetic success of the Vina Robles Hospitality Center."
Woodle adds that stone veneer compares favorably to other materials, including natural stone. "Stone veneer is lighter than true stone, is more economical, constructs more quickly and efficiently, with less waste," he says. "It’s also more ecologically friendly and, because it is produced at a number of regional sites around the country, the issue of hauling it long distances is nearly a non-issue."
Vina Robles’ stone veneer supplier for this project contributes to LEED points for a number of reasons, including the issues of weight and the use of common and sustainable raw materials in its "recipe."
For use on the fireplace, there were a few considerations relative to the heat generated and how it might affect the stone veneer. "The fireplace substrate is concrete block, with firebrick within the wood chamber. A proprietary flue system was utilized which adds to the safety of the installation," explains Woodle. "The stone veneer texture was chosen based upon its realistic appearance, scale, as well as its appearance with respect to locally mined stone. The color was chosen based upon the inherent colors of the surrounding landscape."
Of course, costs figured into the equation as well. "Stone veneer is more cost effective in our geographic region than true stone. It also is ecologically friendly because we’re not mining stone out of the ground," adds Woodle.
Overall, the client was extremely pleased with the final look and quality of workmanship. "The clients are very, very pleased with the overall results, and the stone veneer is a key element in the final aesthetic result.
"We’ve utilized stone veneers on many winery, hospitality, and residential projects and continue to specify them where appropriate," says Woodle, adding that other stone veneer projects include Edna Valley Vineyards, Bianchi Winery, and the Justin Winery and Vineyards.
Stone veneers are proving themselves again and again as an intelligent alternative to solid stone and brick. As their ecological advantages, value and design consistency become better understood, expect to see more "stone" in more interior applications.
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|Stone and Glass in a Landmark Library
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Stone veneer plays a prominent role in a 32,000-square-foot library in Temecula, CA. A cathedral spine divides the library into three main sections: an administrative area, a children’s library, and a large community room that features a massive 40-foot fireplace.
More than 10,000 square feet of stone veneer was used on the exterior and interiors of the project, including the fireplace and interior accent walls (right).
"We originally considered natural stone, but we liked the look of stone veneer and it saved us a lot of money," says Bill McAteer, construction manager for the city. "It blends beautifully with the hillside and gave us exactly the look we wanted."
"Our goal in using stone veneer was to replicate what is found naturally in the area, but in an economical fashion that could be used today," says architect Craig Whitridge of LPA Inc., the firm that designed the project.
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|HUD Standards for Stone Veneer
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The Department of Housing and Urban Development has established standards for stone veneer. What follows is a list of requirements and installation and construction procedures.
Stone veneer is a manufactured stone product that is similar in color and texture to natural stone and brick veneer. The products are produced from a lightweight concrete mix consisting of Portland cement, lightweight aggregates, admixtures, and mineral oxide colors. The stones are pre-cast in various sizes, shapes and surface textures. The stone has a maximum size of 720 inches2 (0.464m2), with no side exceeding 36 inches (914 mm) in length. The stones have a maximum average thickness of 1.75 inches (44.5 mm) and a nominal oven dry weight of less than 105 lb/ft3(1,362 kg/m3).
- The composition of stone veneer shall consist of one or more of the following:
- Cement meeting the requirements of ASTM C150, C595, or C989
- Pozzolans meeting the requirements of ASTM C618
- Aggregates meeting the requirements of ASTM C33, C330, or C331
- Coloring pigments
- Potable water
Batch sizes may vary from plant to plant depending on the equipment available at each manufacturing location.
- The stone veneer shall have a minimum compressive strength of 1,800 psi when tested in accordance with ASTM C192 and ASTM C39, and pass the freeze-thaw test described in ASTM C67 with a mass loss no greater than 3 percent.
Installation of stone veneer shall be in strict accordance with the manufacturer’s instructions and local building code requirements. Application to Sheathed Wood Frame Construction:
Studs shall be spaced a maximum of 16 inches (406 mm) on center. The sheathed surface shall be covered with two layers of a water-resistive barrier complying with either ASTM D226 for Type 1 No. 15 felt, UBC 14-1, or a water-resistive barrier meeting the requirements of ICC Acceptance Criteria AC38. Galvanized 2.5lb/yd2 (1.4 kg/m2) expanded metal lath complying with ASTM C847, or 18 gauge woven wire mesh complying with ASTM C1032, shall be attached to the studs spaced 16 inches (406 mm) on center with galvanized roofing nails or galvanized staples. The lath or mesh must be self-furred or use self-furred fasteners.
The fasteners shall be spaced 6 inches (152 mm) on center vertically and shall have sufficient length to penetrate into the studs a minimum of 1 inch (25 mm). A nominal half-inch (12.7 mm) thick scratch coat of Type S or Type N mortar complying with ASTM C270 shall be applied to the metal lath with enough pressure to key into the lath.
When the mortar has become thumbprint dry, score surface horizontally to create a rough surface. The stones shall be adhered to the scratch coat with a nominal half-inch (12.7 mm) thick bed of Type S or Type N mortar with enough mortar to squeeze around the edges. The exposed scratch coat or substrate surface shall not be visible in the joints between the stone.
Application to Open Wood Frame Construction
Studs shall be spaced a maximum of 16 inches (406 mm) on center. Open stud framing shall be spaced a maximum of 16 inches (406 mm) on center. The stud framing shall be covered with a minimum of one layer of a water-resistive barrier complying with either ASTM D226 for Type 1 No. 15 felt, UBC 14-1, or a non-perforated water-resistive barrier meeting the requirements of ICC Acceptance Criteria AC38. Paperbacked galvanized expanded 3/8 inch (9.5 mm) rib metal lath complying with ASTM C847, with a minimum weight of 3.4 lb/yd2 (1.8 kg/mm2), shall be attached to studs 6 inches (152.4 mm) on center vertically with galvanized roofing nails or galvanized staples.
The fasteners must penetrate the stud by a minimum of 1 inch (25 mm). The lath paper must be equivalent to the requirements of the water-resistive barrier listed above. If the lath paper does not meet the water-resistive barrier requirements, apply a second layer of water-resistive barrier meeting the requirements above. The fasteners shall be spaced 6 inches (152 mm) on center vertically and shall have sufficient length to penetrate into the studs a minimum of 1 inch (25 mm).
A nominal half-inch (12.7 mm) thick scratch coat of Type S or Type N mortar complying with ASTM C270 shall be applied to the metal lath with enough pressure to key into the lath. When the mortar has become thumbprint dry, score surface horizontally to create a rough surface. The scratch coat shall cure for a minimum of 48 hours. The stone shall be adhered to the scratch coat with a nominal half-inch (12.7 mm) thick bed of Type S or Type N mortar with enough mortar to squeeze around the edges of the stone. The exposed scratch coat or surface shall not be visible in the joints between the stones.
Application to Masonry Surfaces
Ensure the masonry surface is clean of debris, paint, release agents or other bond break material that could affect the adherence of the stone veneer. The surface can be cleaned by acid washing or by sand or bead blasting. Spray water onto the surface after cleaning to see if water beads on the surface. If it does, clean again or apply 2.5lb/yd2 (1.4 kg/m2) metal lath meeting the requirements of ASTM C847 before applying the scratch coat and stone.
A nominal half-inch (12.7 mm) thick scratch coat of Type S or Type N mortar complying with ASTM C270 shall be applied to the concrete or masonry surface and scored horizontally. The stone shall be adhered to the scratch coat with a nominal half-inch (12.7 mm) thick bed of Type S or Type N mortar with enough mortar to squeeze around the edges. The exposed scratch coat, concrete or masonry surface shall not be visible in the joints between the stones. The exposed scratch coat or surface shall not be visible in the joints between the stones.
Check with your local building code to determining if there is a requirement for weather protection for the masonry wall.
All flashing must be installed in accordance with building code requirements. To maintain the weather-resistance of the exterior wall on which the stone products are installed, rigid, corrosion-resistant flashing and a means of drainage shall be installed at all penetrations and terminations of the stone cladding. Flashing type and locations shall be in accordance with the requirements of the applicable code.
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Interiors & Sources’ Continuing Education Series articles allow design practitioners to earn continuing education unit credits through the pages of the magazine. Use the following learning objectives to focus your study while reading this issue’s article. This article has been approved for one hour of continuing education credit (0.1 CEU). To receive credit, please read the article and take the test associated with it to receive a certificate of completion.
After reading this article, you should be able to:
- Describe the similarities and differences in the makeup of stone veneer and natural stone
- Understand how stone veneer is installed
- Discuss the advantages of stone veneer over other materials
- Describe installation methods and requirements