Wall Systems

Wall systems typically consist of metal wall panels and girts. Girts are cold-formed “C” or “Z” shaped sections and are attached to the columns of the primary frame to support the wall panel against lateral loads. They may frame into the column webs or be attached to the outer column flange. Flush framing increases usable building floor area. The panel and girt act in concert to resist pressure and suction placed on the system by heavy winds. Continuous spanning (lapping) girts are available to provide additional economy. Varying wall member depths and material thickness are offered for flexibility of design, allowing deeper members to span greater distances economically.

Metal wall panels are available in many gauges and textures, some with embossed or stone-coated metal that replicates the look of stucco. Manufacturers will stock standard colors and can obtain special colors from their suppliers to match architectural requests. Often, the exteriors of the metal panels are integrated with other materials—such as brick, precast concrete, glass, stone, or wood.

Two primary metal wall options are available, which are field assembled or factory insulated metal panels (IMP). Other traditional load bearing or facade wall materials can also be used, such as tilt-wall or concrete masonry units (CMU).

Field assembled systems: This system provides metal exterior panels and insulation (typically fiberglass) and may include interior metal liner panels. Advantages include rapid erection, cost-competitive materials, and quick and easy panel replacement. Openings for doors and windows are created quickly. In addition, the panels are lightweight, so lifting equipment is not required—nor are large foundations or heavy spandrels. Acoustic surface treatments are easily and affordably added to interior panel walls.

Insulated metal panels: This system consists of an outer panel and an interior face formed over an insulating core, usually a foam material. It is normally fastened outside the girt. Panels providing insulating values are available from manufacturers. This system incorporates a hard surface interior metal liner panel, rather than exposed faced-fiberglass, and is normally fastened to the building using concealed fasteners to produce a clean appearance.

Two types of fastener systems are available: exposed fastener or concealed fastener systems.

Exposed fastener systems: Panels vary in depth and are available in widths of 2 feet to 4 feet. Thickness ranges from 26 gauge to 20 gauge steel (a lower number indicates thicker material). The most common wall panel thickness is 26 gauge. Wall panels are attached to “C” or “Z” girts with self-tapping screws, self-drilling screws, or expanded fasteners, and joined to each other at their sides and ends in lap joints. Profile panels range in depth from 1 inch to 2 inches and are available in widths from 28 to 40 inches, and are available in varied patterns and colors.

Concealed fastener systems: Designed with edge joints that conceal the fasteners, the panels are available in many different profiles and finishes. These panels usually have deeper cross sections and can allow longer spans between girts.

Roof Systems

Roof systems are made up of two components: purlins and roof panels.

Purlins: Two types of purlins support the weight of the roof and any applied loads—cold-formed steel (either “Z” or “C” sections) and open web joists. The purlins work to transfer these loads to the primary structural system. The “Z” or “C” sections can be simple spans but are more commonly used as continuous beams between frames. They can be used for spans of up to 30 feet. Continuous span (lapping) purlins are used for greater economy. For spans greater than 30 feet, open web steel joists or deeper “Z” sections may be used for purlins. Varying roof member depths and material thickness are available for flexibility of design, allowing deeper members to span greater distances economically. Open web steel joists are utilized as simple spans and allow for greater spans. Hot-rolled bar joists or cold-formed long bay purlins can be used to span up to 65 feet.

Roof panels: Panels are fabricated from light gauge steel as a lap seam roof or a standing seam roof system. The panel of a lap seam roof is typically 1 inch to 11/2 inches deep, 26 or 24 gauge (or heavier) in thickness, and connected together by lapping the panels. A sealant is installed between the panels at the side laps and end laps and secured with fasteners. These systems are also known as “through-fastened” roofs because the structural panel fasteners are exposed. The selection of panel depth and thickness is affected by the roof load, purlin spacing, and insurance considerations.

Standing seam panels: The seam between two standing seam panels is often made in the field with a machine that produces a cold-formed, weather-tight joint at the side lap of each panel. The panel is attached to the purlins with a steel clip concealed inside the seam, which creates a secure attachment while permitting thermal expansion and contraction of the roof plane. Since most of the through-the-roof fasteners are eliminated, a continuous, single-skin membrane results. Thermal spacer blocks, made from high R-value foam insulation, can be placed between the panels and purlins to provide a consistent thermal break for energy compliance. The metal standing seam roof can be used to renovate and restore old, leaking flat roofs, upgrading them to better-than-original condition by adding a slope. This simple procedure immediately turns a flat roof into a water-shedding surface. Various finishes and colors allow architectural variety, with typical gauges ranging from 24 to 22. The products can be used in either a structural, low-slope application or to create a signature architectural metal roof design.

Bracing requirements: To complete the roof system, metal building manufacturers typically provide bracing for the purlins. Depending on the design assumptions, bracing systems may incorporate steel straps, channels, or sag angles. All of these systems span from purlin to purlin. For a standing seam roof system, the amount of lateral support provided by the panels to the purlins is determined through testing if it is to be included in the design. This is why a standing seam roof system from one manufacturer may have more visible bracing than another.