Natural stone has long been a staple of building construction primarily due to its strength, durability and aesthetic appeal. With endless design and functional possibilities that enhance the look and performance of exterior or interior environments, natural stone will continue to be a component of modern design and construction.

However, much like other building materials, producers of natural stone building products are evolving their offerings to meet the demands of architects and building owners for cost-effective, installer-friendly materials that lead to high-performing and resilient buildings and homes. As such, a growing number of building designers are turning to lightweight natural stone panels with honeycomb reinforced backing, as these systems provide the beauty of natural stone but with considerable material, labor, and installation benefits.

In this article, we will cover the basics of natural stone panels, taking a look at how these systems are produced, how they differ from traditional dimensional stone and their performance attributes.

The Basics of Lightweight Natural Stone Panels
Lightweight natural stone panels can be custom-made from a number of stones including marble, granite and limestone. Most are manufactured in a four-layer, ‘sandwich-panel’ where an approximately 6-mm (1/4-in.) thick stone veneer is bonded to a waterproof fiberglass layer using epoxy that also secures the aluminum honeycomb center with a chosen backing. This is accomplished by laminating the layer of epoxy-reinforced, fiber-rich cloth directly over the honeycomb to provide crack and fracture resistance as well as flexural and impact strength. The stone veneer, fiber-rich epoxy saturated material, and aluminum honeycomb backing are then placed into a press for laminating the layers together, creating a nominal 25-mm (1-in.) panel. This results in a panel that is 80 percent lighter but provide impact resistance that is 60 times greater than the solid slabs they were produced from. 

In addition, the epoxy-reinforced fiber skin backing provides an additional weatherproof barrier that does not exist with a solid, porous stone cladding system. These properties make natural stone panels an ideal solution for multi-story buildings where cladding durability and redundancy in moisture management are paramount.

Benefits of Lightweight Natural Stone Panels

Lower installation cost as compared to traditional dimensional stone is one of the largest advantages of selecting these composite panel systems, with the main savings achieved through speed of installation. Because panels weigh between 5 and 7 lbs. per square foot, they can be easily lifted and installed by three-person crews using boom lifts, scaffolding, or scissor lifts. In fact, some studies show the lighter weight resulted in installation speeds nearly 20 percent faster than aluminum composite panel systems. For example, an installation crew can install 25 to 50 panels in a single day; as opposed to anchored stone where crews may only be able to install materials covering the same area in a single day.

The labor costs are further reduced by the simplicity of the system. The panels arrive at the jobsite as ready-to-install. The predesigned panels are available in standard-sized units and do not require complex layout or design. Since panels are attached using an interlocking channel system, it alleviates the need for mortar or other specialized skills required to install mortar-bedded stone. This straightforward installation allows for the use of a variety of readily available trades like carpenters and metal panel installers. It also decreases the time to install the product by a significant amount compared to other building materials.

Beyond the installation benefits, natural stone panels offer a multitude of performance characteristics that make these systems ideal for the industry’s focus on high-performance buildings:

• High Resiliency
• While lightweight, natural stone panels have 60 times the impact resistance of the slab from which they were produced, making them an ideal option for HVHZ requirements of the Florida Building Code. These panels are also a cladding possibility where code prohibits the use of traditional masonry due to seismic activity.

• Moisture Management
• These composite panels also have the ability to serve as a rainscreen. In this application, the primary water-resistant barrier is located on the surface of the backup wall, joints are left unsealed, and the stone panels provide a rain screen that helps swiftly remove any moisture that may seep behind. 

• Low Maintenance
• When properly constructed, stone panel systems require relatively little maintenance as compared to other wall systems. Typically, the only maintenance required is replacement of sealant in joints between panels; the time frame for this activity depends on the sealant used but usually ranges from every 7 to 20 years. Further, panels can be cleaned using conventional power-washing methods, and a damaged panel can be easily replaced without compromising the entire cladding system.

• Safety
• The natural stone veneer on aluminum honeycomb panels are virtually-noncombustible, therefore, in the case of a fire, the panels are less likely to shatter. Instead, the stone flakes away only as small stone chips. This is much safer for emergency personnel as well as civilians around the area.

Sustainable Attributes

Sustainable building remains at the forefront of high-performance building design. The unique characteristics of honeycomb reinforced stone panels can help construction teams meet green building objectives in a number of ways. Specific sustainable attributes of lightweight panels include:

• Lightweight panels use less than 50 percent of the natural stone resources than 3 cm natural stone does to construct the same square footage—greatly reducing the environmental impact as well as resources lost from quarrying. Lighter walls mean less support required from the building structure.
• Composite panel systems offer durability, reduced energy costs from the better insulation of the wall system and space savings, while lowering transportation costs in comparison with other building materials.
• Lightweight natural stone panels can also be re-used in renovation and re-cladding applications, allowing for deep-energy retrofits of existing structures.

These features meet many of the requirements of sustainable building design, including contribution to points in various LEED categories, including Energy & Atmosphere, Materials & Resources, Indoor Environmental Quality, and Innovation & Design.

Conclusion

Natural stone composite panels have casted a new light on natural stone for exterior cladding applications. These systems have proven to be a cost-effective option providing the beauty, durability, and low maintenance that has made natural stone one of the most widely used building materials throughout history. By taking this time-tested building material and advancing it with today’s technology, we have opened the door to a nearly endless list of possibilities that will help ensure natural stone is well-positioned to meet the needs of today's and tomorrow’s high-performance buildings.