Exterior CFS Systems
Features & Benefits
Cold-formed steel framed exterior wall systems offer designers, owners, developers, and contractors many advantages. First, these systems offer design flexibility while providing improved sustainability and non-combustibility. Next, they provide assurance to the owner that indoor air quality standards and a shorter pay-back system solution have been met. Finally, to the contractor, a cold-formed steel framed exterior wall solution provides a shorter construction cycle, with readily available, cost efficient building materials.
Each individual component that comprises a cold-formed steel framed exterior system helps support a sustainable design solution. The primary individual components of a cold-formed steel framed exterior system include:
1) Gypsum Panels -The Gypsum Association has established a special Web site, www.gypsumsustainability.org, to provide designers with information about gypsum panels and sustainability. From a recycling standpoint, for more than 50 years, the gypsum industry has used recycled paper for its face and back papers. More recently, the industry has begun to use “synthetic” gypsum, a by-product of the “flue gas desulfurization” process used in coal-fired electrical generation facilities. In the year 2010, it was conservatively estimated that 45% of the gypsum mineral used in gypsum panel production was synthetic gypsum.
2) Cavity Insulation - The National Insulation Manufacturers Association has devoted a portion of its Web site to sustainability. The Association provides extensive information about glass fiber, rock wool, and slag wool type insulation. According to the Insulation Manufacturing Association, “Using recycled materials in the manufacture of insulation prevents depletion of natural resources. Today’s fiber glass insulation can contain upwards of 70% recycled glass, but on average will typically contain 50% recycled glass. Slag wool insulation can contain up to 90% recycled content, but on average, uses approximately 70% blast furnace slag.”
3) Continuous Insulation - There are three types of continuous insulation used in cold-formed steel framed exterior walls. They are: Expanded Polystyrene (EPS), Extruded Polystyrene (XPS), and Polyisocyanurate (PIR). Discussing EPS insulation, The Foam Sheathing Committee stated that “the energy invested in the production and delivery of Expanded Polystyrene yields an exponential benefit to the environment by providing substantial energy savings and critical reductions in greenhouse gas emissions when EPS is used to insulate homes in North America”. The Committee based its conclusion upon a Life Cycle Analysis conducted by Franklin Associates for the EPS Molders Association. Extruded Polystyrene (XPS) not only offers the same benefits as EPS, including improved operational energy savings for the completed structure, but may have recycling potential as well. Polyisocyanurate (PIR) has the highest thermal resistance of the three types of continuous insulation, and therefore offers the greatest energy savings potential. For more information about these environmental profiles, visit the Foam Sheathing Committee’s Web site.
4) Cold-Formed Steel Framing Sustainability - Steel is the world’s most recycled material (Source: World Steel Organization). Since 1990, the steel industry has reduced the amount of energy required to manufacture steel by 27%. In addition, all steel framing components have recycled content, and according to the AISC, this recycled content may be as high as 90%. Finally, 95% of the water used in steel production is recycled. The transition from the integrated process of making steel to the electric arc furnace has blanketed the North American continent with small energy efficient steel production plants. The U. S. Green Building Council, USGBC, has recognized the benefit of using regional materials in the LEED (Leadership in Energy and Environmental Design) certification program. To find more information about this topic, visit: www.steelframingassociation.org.
Short Construction Cycle
According to the Steel Framing Alliance, mid-rise buildings built with cold-formed steel framing may have as much as a three month shorter construction cycle time than that of traditionally heavier construction materials. Additionally, construction scheduling may be more predictable when using cold-formed steel framing since it is not a weather sensitive material, and panelization allows for tighter construction cycle scheduling.
Most of the building materials, including gypsum panels, cement boards, rock wool insulation, steel framing, and stucco, commonly used in cold-formed steel framed systems are recognized by the model codes as non-combustible. Using non-combustible materials helps insure that the structure will meet or exceed life safety standards. Also, the use of non-combustible materials qualifies these assemblies in what the codes recognize as Type I buildings.
The American Heritage College Dictionary (2004) defines innovation as “marked by or given to innovations” and “something newly introduced”. According to these definitions, cold-formed steel framed systems are uniquely innovative. Although fundamentally, cold-formed steel framing systems have been successfully used since the early 1960’s, material science and technology advances have elevated these systems literally to new and dynamic design heights. Many of the building materials (gypsum panels, steel framing, insulation, and finishes) that comprise a cold-formed system have undergone significant transformation. These new advances have helped to create cold-formed steel systems with superior performance characteristics (fire, acoustics, structural, moisture, and aesthetics). The system’s enhanced performance not only affords the architect greater design flexibility, it also provides the owner with a system that facilitates greater operational energy.
Aesthetic Design Flexibility
The use of cold-formed steel framed systems provides the designer with almost limitless design flexibility. Once the steel is erected and the exterior sheathing applied, the designer can specify finishes with new textures and colors, including mixing more than one finish together, (brick, stucco, tile, stone, and siding) all on the same substrate. Also use of cold-formed steel framing means that the exterior envelope no longer needs to be thought of as a vertical flat plane. Exterior walls now can be canted or even curvilinear.
Low-Cost, Short Payback
According to the Steel Framing Alliance, a shorter building cycle time allows tenants to move in faster, which increases the landlord’s revenue stream and improves the business model under which the building was designed and built.