Covering it all: Investigating lightweight cladding

by arslan_ahmed | December 15, 2023 8:00 pm

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By Karine Galla

Lightweight cladding is gaining traction in the construction industry. With advancements in material science, the benefits of such cladding are increasing, and it is no longer necessary to use heavy materials such as masonry, concrete, metal panels, precast, porcelain, or even fiber cement to achieve the look of brick, wood, concrete, or metal. With the latest industry innovations, all these looks for building exteriors can be achieved using lightweight claddings. Aesthetics aside, sustainability and energy efficiency are major advantages, and installation is safer and easier for crews on site.

Cutting down on carbon

Carbon emissions from the building sector are significant, and they have an impact on the environment. In fact, according to the New Buildings Institute (NBI), “Building operations and construction-related activities are responsible for approximately 39% of humanity‘s global greenhouse gas (GHG) emissions. More than a fourth of those are embodied carbon emissions, those associated with the production of building materials, construction activities, operations, and end of life.”¹ Therefore, both embodied and operational carbon are crucial considerations in today’s construction sphere.

Operational carbon is the amount of GHG emissions that are released during the in-use phase of a building. This includes the use, management, and maintenance of a product or building. In short, it takes into account the variety of carbon emission sources that are active throughout the operating period of a building.

How do lightweight cladding materials positively affect the carbon footprint? Starting from the top, lightweight materials are thinner, lighter, and take up less space during transit. This translates to less trucks overall and less gas expended to transport materials to the job site. By nature, lightweight materials also simply make for a lighter load to haul, which impacts fuel efficiency. For every 453-kg (1,000-lb) increase of vehicle weight, fuel economy drops by approximately 0.5 percent.² Reducing the weight of the materials shipped across multiple truckloads can result in significantly reduced environmental impacts and diminished carbon emissions.

There are also key differences when it comes to the preparation of lightweight cladding materials compared to their heavier counterparts. Consider masonry cladding that requires heating and drying for extended periods of time in an 800-degree kiln. This consumes a great deal of energy. With lightweight cladding alternatives such as resin-cast brick, construction stakeholders can achieve the look of masonry, but in a much lighter-weight solution that takes a fraction of the energy to fabricate.

From an operational carbon perspective, lightweight cladding options that are installed as part of a fully integrated system deliver even greater savings. Innovative systems that combine lightweight, high-performance cladding, superior air and weather barriers, and excellent thermal properties via continuous exterior insulation save on energy consumption, generating additional cost savings for owners. Therefore, specifiers can choose systems that meet the most stringent building code standards, as well as those that meet requirements for an NFPA 285-compliant assembly.

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On-the-wall energy performance

One of the most important benefits of lightweight cladding is its on-the-wall energy performance. Take exterior insulation and finish systems (EIFS), a lightweight cladding system that provides a continuous insulated building envelope at about 0.5 kg/m² (1.5 lb/sf). EIFS is applied in multiple layers over exterior sheathing to create an energy-efficient, fire-resistant, low-maintenance, and versatile exterior cladding.

A study by Oak Ridge National Laboratory (ORNL) showed that EIFS walls perform better than several other wall types for moisture and thermal performance. The 15-month ORNL study conducted in the southeastern region of the U.S. showed EIFS outperformed walls made of brick, stucco, concrete block, and cement board.³

• EIFS are sustainable, durable, and resilient.
• EIFS are among the most water-resistant
  exterior surfaces.
• EIFS have passed the major fire resistance tests that are required by the building codes. This includes fire resistance, ignitability, intermediate multi-story, and full scale multi-story corner tests.

EIFS is just one example of a lightweight cladding system that delivers value across residential, multi-family, and commercial construction sectors. From a visual perspective, if a design team is looking for something other than EIFS, there are other lightweight cladding options that can provide the same benefits and still achieve the true look of what they are designed to mimic.

Authentic aesthetics

Innovations in cladding technology have allowed architects and specifiers to achieve a variety of cladding looks by employing a unified, tested, and higher-performing system compared to traditional materials. For example, architects can now specify lightweight, flexible, resin-cast wood grain planks for a building’s exterior or interior that look like real wood, but without the performance downsides. This provides a durable, realistic, and low-maintenance alternative to natural or engineered wood cladding. Plus, these new products can be integrated within fully engineered wall systems that include all the control layers (air/water/vapor, moisture, thermal, and durability) for modern building performance while providing a one source solution and warranty. This allows architects to meet project demands for building exteriors that require a number of colors, textures, or materials on the same structure with seamless integration of the control layers behind each aesthetic. In this instance, the only thing that changes is the building’s exterior finish.

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Instead of real brick, facades today can feature flexible resin-cast brick shapes to achieve a variety of unique designs. These materials give designers freedom when it comes to color choice, and they consume significantly less energy to manufacture and transport, compared to traditional heavy bricks.

From a health perspective, there is no dust generated from resin-cast brick, and because it contains very little silica, it keeps production workers and installers safe. Further, these resin-based bricks and organic mortars are cement-free and significantly reduce the risk of efflorescence, which is the whitening of the material due to the migration of salt to the surface of porous materials, often occurring with real brick or concrete. From an installation perspective, these thin, pre-formed brick shapes are fast and easy to install, no special tools are needed to cut them, and there are no concerns about hauling a load of heavy bricks around the job site.

More visual options for lightweight claddings include those used to create facades resembling split face block concrete masonry units (CMU). Designers can circumvent having to specify heavy CMUs and instead choose lightweight cladding systems that offer products that achieve the look
of a true cement block.

The construction community has access to ready-mixed, acrylic-based materials that are applied to a building’s substrate using simple tools such as a finishing trowel. Once completely dry, applicators sand down the surface to the desired texture, wash the finished facade, add formwork marks, and apply a clear coat sealer for the desired gloss. The end result is an exterior wall that looks like CMU, but is much lighter and can also be finished in a variety of colors or textures. In addition to a CMU appearance, this same method can be used to create the look of brick, stone, tile, wood, limestone, metal, and more. Plus, behind the facade finish, these aesthetic options can be part of an integrated wall system that combines insulation and weather barrier layers to ensure long-term building performance and thermal efficiency.

User-friendliness

It is clear that installing lightweight claddings is simpler and safer for construction crews. Consider the scenario of installing cladding on a multi-story commercial building. Installing heavy cladding panels requires specialized equipment and lifting substantial materials high above ground; and this brings inherent safety risks. Compare this to applying lightweight materials to the face of a building.

Made for the retrofit market

While lightweight materials make sense in any construction environment, they are particularly suited to the retrofit market.

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The most sustainable way to build a structure is by renovating an existing one. This is the most eco-friendly option, but it still presents a host of challenges. The insulation typically needs to be installed if not upgraded, and the exterior walls often need to be revived. Instead of adding additional layers of heavy materials or doing a complete reclad, which increases the embodied and operational carbon of the building, construction stakeholders are selecting lightweight products that minimize carbon emissions, and also are less of a disturbance for the occupants of the buildings.

For the renovation of aging structures, lightweight EIFS assemblies are an ideal option. With EIFS, if the building has an existing brick or CMU exterior, contractors can overclad the structure by putting a liquid-applied weather barrier over the existing masonry, a layer of continuous insulation (ci), the application of a base coat and mesh, and then finally the finish that the customer desires. This is dubbed an overclad, and it can only be done with lightweight cladding.

The overclad method saves time and money for the owner funding the renovation and for the installation crews as well. It is also a much more sustainable option than demolishing a building, dealing with material waste, and expending considerable amounts of energy to construct a new one.

Another benefit is that if an existing exterior is already completed with EIFS, overcladding is still an option for the future because of how thin it is relatively to many other cladding options. For example, if a home or building has EIFS on it, but the owner decides they want to change the cladding to a wood alternative, they can simply install resin-cast wood over the EIFS. Both materials are lightweight, so the structural integrity of the building will not be compromised. This is an important consideration, because the thicker a wall gets, the more impact it has on other portions of the structure, such as the framing of the structure, windows, and doors. In sum, a wall can only be so thick. Therefore, thinner, lightweight claddings are advantageous for any potential building retrofits in the future.

Finally, repairs to an exterior are simpler with lightweight cladding systems such as EIFS. If there is a minor dent in an EIFS wall, an applicator can cut a section of the material out, fix it, and finish it without any visible inconsistency in the wall’s finish and without compromising the performance of the air, water, or thermal control layers. Compare this to having to replace a metal or fiber cement panel on a commercial building, where crews need to order a replacement panel, wait for it to ship, then uninstall the damaged panel and install the new one. This is more time consuming, and material production and transportation release more carbon into the atmosphere.

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Keeping it light

The benefits of lightweight cladding stretch beyond the performance of the structure itself. Owners, installers, architects, and the living environment can all benefit from these types of materials. This includes lower energy bills, a more comfortable environment for occupants, near limitless design freedom for architects, and a lower carbon footprint for the planet.

Lightweight claddings deliver on the performance that today’s structures require and have proven to be an excellent fit for the retrofit market to rehabilitate buildings of the past for another lifetime of use. With sustainability at the forefront of the conversation, lightweight claddings help limit carbon emissions. With so many aesthetic options, they also meet any project’s design vision. For the many stakeholders involved in the construction process, lightweight claddings can lead to a holistic solution for the building envelope, one that impacts everyone on the project.

Notes

¹ Learn more about embodied carbon by visiting, newbuildings.org/code_policy/embodied-carbon/[6].

² Examine the fuel economy weight at www.internationaltrucks.com/blog/fuel-economy-weight[7].

³ Read the report, “Energy – Wet, warm wall worries.” Oak Ridge National Laboratory, www.franklin.in.gov/egov/documents/1501244146_07449.pdf[8].

⁴ Refer to the “Benefits of EIFS.” EIFS Industry Members Association, www.eima.com/eifs/benefits[9].

⁵ Learn more about Environmental Product Declarations at www.stocorp.com/epd/[10].

 Author

Karine Galla is director, product management, for Sto Corp. She has more than 20 years of experience in product marketing in exterior insulation and finish systems (EIFS), stucco, air and moisture barriers, and other materials. Galla has a master’s degree from the University of Lyon, France. She is multilingual and holds AWCI’s EIFS Doing it Right and Building Envelope Doing it Right certifications, as well as the ISO Internal Lead Auditor certification from Georgia Tech.

Source URL: https://www.constructionspecifier.com/covering-it-all-investigating-lightweight-cladding/

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