Understanding the Benefits of Extruded Concrete Panels for Rainscreens

Extruded concrete is an ideal material for rainscreens for many reasons. The manufacturing process creates a material that is thinner, stronger, and more manageable for designing and installing rainscreens. Also, extruded concrete is noncombustible and is available in a wide range of colors and finishes.

Andrew Rogers, president of Rieder North America, an extruded concrete manufacturing firm, has seen its products used in many applications.

“The ¹/₂-inch thick extruded concrete for flat rainscreen walls panels has been proven with over 10 years use in all parts of USA and Canada. The potential uses for this product are vast, including three-dimensional and curved parts for exterior and interior elements, flooring, and furniture,” he explains. “The future development of the product is also extensive, including thermally active facades, larger format panel sizes, and new and exciting textures, colors, and surfaces.”

Out of the concrete-based rainscreen materials, extruded concrete is quickly becoming a popular choice, and for good reason. Rainscreen panels made from extruded concrete layered with glass fiber can be rapidly produced, and the finished product combines many of the desired attributes necessary for quality rainscreens. The most notable qualities are that the finished product is a thin (¹/₂-inch), relatively lightweight, strong, and durable panel that is noncombustible and available in a range of colors and surfaces. By choosing to use rainscreens made from extruded concrete, designers can meet their aesthetic needs, all while using a superior product that is easy to install and will protect the building for a long time.

There are many advantages to extruded concrete rainscreens, most beneficial of which is the thickness tolerance. Cast-in-place concrete loses thickness tolerance, especially with a large sheet. Also, the extrusion is very fast, and it has the possibility of high output or production capacity. Some manufacturers can produce up to 30,000 square feet per day.

A ¹/₂-inch panel made of alternating layers of 3 millimeters of concrete and another layer of mesh made of glass fiber, followed by another 3-millimeter layer of concrete with chopped glass—repeated until ¹/₂-inch—makes for a high tensile strength and a durable panel.

The disadvantages don’t necessarily outweigh the advantages, but they need to be taken into account. For example, one of the limitations of extruded concrete is that it is limited to the width of the machine. So, if the machine width is 48 inches, that is the maximum-width panel that is available.

A beneficial feature of extruded concrete panels is that the products are naturally cured, typically for 28 days at room temperature. This curing process means that this aspect of their production requires very low energy use. If we compare this process to alternatives, such as aluminum, high-pressure laminates (HPL) coated with resin and paper, or cement board, extruded concrete comes out on top for manufacturing energy efficiency. The products are also all natural and thus are not prone to off-gas vapors in the way that other products might.

Extruded concrete panels have a wide range of color and texture options, which in turn makes them versatile for project design. Iron oxide is usually used to attain the product colors. The natural pigments blend in well with the natural environment to help designers achieve a seamless look between the project and the local landscape. In addition to colors, the panel surfaces can be sandblasted and honed to create vivid textures.

Finally, use of the product is highly versatile, especially when it comes to including original designs on a building’s exterior. Designers have the option of different panel sizes and shapes; for example, slat wall panels that can be easily installed by contractors or do-it-yourselfers. These panels require very little, if any, maintenance. In comparison to wood slat cladding, which needs to be treated or painted to maintain its appearance and durability, extruded concrete panels will retain their look through the lifetime of the product.

Another innovative element of the extruded concrete process is that it can be folded when wet and thus made into different shapes. Most commonly, panels are molded into “U” or “L” shapes that can be used to animate a building’s exterior, but the material can also be put in molds to create curved components. Architects may use U-shaped extruded concrete panels as exterior fins attached to the curtain wall to improve the solar shade capabilities on tall buildings. This 3-D design option has put concrete panels in direct competition with the traditional aluminum fins.

Conclusion

Rainscreen systems are quickly becoming an accepted part of building design, and for good reason. A clearly thought-out water-mitigation plan is an essential part of a project, and that plan can easily include durable, strong, stylish panels that make a bold statement. Extruded concrete panels bring a lightweight, naturally colored, and environmentally friendly option to the rainscreen system. Moreover, this versatile process of extruded concrete is quickly becoming a new way for designers to create 3-D forms that go beyond the basic flat panel.

OTHER OPTIONS: FINS, INTERIOR, DECKING, ROOF APPLICATIONS, FURNITURE—THE SKY IS THE LIMIT

© Ditz Fejer

Extruded concrete is a versatile material. Here U-shaped ultra-thin folded fins made of extruded concrete were used for Boston University, Center for Integrated Life Sciences & Engineering.

Rainscreen and cladding systems aren’t the only use for extruded concrete forms. The material can be folded when wet and made into “U” shapes, “L” shapes, or put into a mold for curved parts. These unique shapes and designs can be incorporated into both interior and exterior features.

Folded concrete can replace traditional aluminum “fins” on building exteriors. Such fins provide solar shades on tall buildings and decorative adornments to the structure. With new 3-D concrete design as an option, fins can be designed and then installed directly onto the curtain wall.

Decks and rooftops can also benefit from the strength, durability, and light weight of extruded concrete panels. As a deck surface, for example, the material is able withstand foot traffic and deflect rain and snow, making it an affordable alternative to traditional wood decks. Moreover, the difference in maintenance requirements between a traditional wood deck and a concrete panel design is impressive: where wood requires stains, sealants, and occasional power washing to keep the wood in good shape, concrete will maintain its appearance without any risk of deterioration. This fact alone makes it a good choice over wood, which regardless of how well it is cared for will at some point begin to degrade, either from exposure to the elements or from bug infestation.

Moving away from exterior cladding, extruded concrete forms can also be created to enhance building interiors, whether through interior finishes or even custom-designed concrete furniture, such as tables, chairs, benches, or couches.

CASE STUDY: ARIZONA STATE UNIVERSITY, SUN DEVIL FITNESS COMPLEX EXPANSION

© Bill Timmerman

Arizona State University, Sun Devil Fitness Complex Expansion

Like many universities and colleges across North America, Arizona State University (ASU) recently updated its sports complex and student recreation center as a way to meet student needs for a community and wellness-based campus. The 2013 project also created a new and iconic structure on the campus, which houses a court for indoor hockey and soccer, five new basketball courts, a fitness center, a wellness center, a lounge, and gaming areas.

One of the core challenges the project architects faced was developing a new building on an already dense urban campus. This meant building vertically in a creative manner that would fit in the planned amenities, such as a swimming pool, fitness center, two soccer fields, basketball courts, and a multiuse gymnasium for concerts, campus events, and conferences. As a solution, the three of the six courts were placed on the second level, overtop the other courts and fitness area, with the swimming pool and deck area in the center. This stacked design successfully created shaded public spaces and introduced floor-to-ceiling views of the rest of the facility and the surrounding campus.

This design was in response to the call for more open space on the campus, and for an open and inviting gateway to this part of the university. The vertical nature of the design and its openness was also a prime candidate for using exterior cladding panels made from extruded concrete.

The material lends itself perfectly to the task at hand by providing an aesthetically designed exterior that protects the building and adds to the overall energy efficiency required for a desert environment. In addition to the concrete panels, the building integrates rooftop solar-thermal photovoltaic systems, which, when combined, contribute to a 70 percent energy use reduction compared to the original recreation center design.

The lightweight material was colored in different shades of natural “sand” tones, thus fitting in well with the theme of the Arizona landscape. Varying panel dimensions add a modern aesthetic to the design, in contrast to the original suburban designs of the original campus and recreation center.

Designers used the vertical nature of the building to create shade when possible, with each layer cladded in a pattern of panels. While the Tempe, Arizona, desert climate does not necessarily require the same level of moisture protection that other parts of the country might, the extruded concrete panels provide an excellent rainscreen as well as a means of deflecting solar load on the building.

This project received 17 out of 19 points for optimizing energy performance, helping it achieve a LEED Gold Certification. The precast, extruded concrete panels added to the energy efficiency and contributed to helping the project achieve the LEED designation. With the solar panels added to the building and a solar heater added to heat the pool, the project attained a perfect score for being able to create on-site renewable energy. The design also embraced passive cooling with a breezeway that funneled air through shaded sections near the core, thus providing natural cooling and shade.

Andrew A. Hunt, vice president, Confluence Communications, has 16 years of experience in green building and has produced more than 100 educational and technical publications. www.confluencec.com

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