Evolution of the Metal Building Components Industry

Metal building components have been in use ever since iron and steel became commonly available during the 1800s. However, coordinated metal building components as we know them today really got their start during the 1900s, with a lot of significant developments happening just in the past 40 years. Here’s a quick overview:

1970s:

During the 1970s, the emerging metal buildings industry was primarily focused on providing pre-engineered solutions for commercial, industrial, and agricultural customers, mostly in the range of 10,000-square-foot buildings or less. The use of lighter-weight, tapered-end steel sections and bolted end-plate connections was beginning to be developed for widespread use, based on industry research. The development of technology that allowed for new methods of steel fabrication created growth for existing companies and helped new ones to form, such as MBCI in 1976. The energy crisis of the time brought interest in creating better insulation solutions.

Metal Building Components Plant Location
MBCI Lubbock, Texas Plant

1980s:

This was a period of growth along with the rest of the construction world. New plants and facilities were opening up in response to growing customer and market needs. New coating technologies were coming available that provided  better corrosion resistance and allowed for more customers to consider using metal buildings. Technical research into wind loading for walls and wind uplift for roofs brought updated means and methods to address these critical structural engineering conditions.

1990s:

During this decade, the volume of metal buildings and tons of steel processed nearly doubled. More building types were being constructed out of metal building components as architects, engineers, and owners saw the flexibility, time savings, and cost efficiencies involved. Retail facilities, offices, even schools started to incorporate metal buildings and their components into their planning and construction. With this growth and expansion, technical issues such as snow loads and employee issues such as OSHA regulations were hot topics of research and focus.

Metal Building Components featuring Legacy Junior High
Legacy Junior High School Featuring PBU Metal Panels

2000s:

With strong momentum and growing success around the country, the industry began to offer more-diverse product offerings and components. Insulated metal sandwich panels with both interior and exterior finishes became more common. New roofing finishes and appearances became available. Structural research into seismic effects on metal buildings was conducted in response to California earthquakes, and solutions were determined. Further work was done on energy performance of metal buildings in response to energy codes and customer requirements. Additional work was undertaken on updated engineering guidelines for tapered structural members and exterior wall and roof finishes and styles. This included the use of horizontal instead of vertical siding systems and smooth-surface solutions.

A Look at Today in the Metal Building Components Industry:

The metal building industry has clearly evolved and come a long way from somewhat humble beginnings. Today, full systems or components can be found in a wide range of buildings types, creating highly attractive solutions that are often not recognized as metal buildings. Continued industry research helps manufacturers provide high-quality products that meet the demands of the larger building industry. Continued collaboration and partnerships are helping to foster diversified product offerings and new market penetrations. Overall, the past 40 years or so have been just the beginning – the future of the industry looks strong, and prospects remain high for continued growth.

Snow and Metal Panel Roofs: Part 2

 

In part I of this blog, we discussed what to consider when deciding the roof material and roof slope to build with in snowy conditions. If you have decided to design a roof with metal panels, it is important to use the correct panel seams, evaluate the roof layout and consider long-term weatherproofing, and ensure your roof design fits the needs and function of the building.

Metal Building in Snowy South Dakota

Weathertight Panel Seams

For metal panel roofs less than 3:12 (i.e., low-slope roofs), the panel seams should be watertight. A watertight seam resists water intrusion, so snow on a roof should not become a leakage issue. For metal panel roofs with slope greater than 3:12, the steeper slope means liquid water (e.g., rain) drains very quickly off the roof. Because of this, many seams used for steep-slope metal panels are not watertight. Non-watertight seams can be problematic where snow stays on a roof. Architects should consider using watertight seams (e.g., double lock) and highly water-resistant underlayments in snow areas for all roof slopes.

Roof Layout

A designer should also consider the layout of the roof. Valleys collect snow. Valleys in which one roof area is significantly larger than the other (e.g., a dormer extending from a large roof area) are vulnerable to unbalanced sliding snow. A large snow slide can move across the valley and literally tear open the standing seams and displace panels.

Drifting snow can occur behind HVAC units, at perimeter walls and behind rooftop solar thermal and PV panels. Where a roof transitions from a lower low-slope roof area to an upper steep-slope roof area, snow will collect. Consider the potential snow load and entrapped moisture at these locations; the transition detail becomes critical to long-term weatherproofing.  And, depending on the orientation (e.g., north facing), areas with drifted snow may not see much sunlight, so snow is more likely to stay on the roof for a longer time.

Building Function

As the roof designer, design the building and site to account for the roof’s function. Many designers turn to snow retention devices to keep snow on roofs, especially above pedestrian areas, such as entrances and outdoor seating areas, or adjacent buildings.   Some of these devices rely on adhesive attachment to the panel, which means they rely on the adhesion of the paint to the metal. But physical attachment—e.g., snow fences clamped to the standing seams—is always a more confident, long-term approach than adhesive attachment when it comes to resisting shear/sliding loads. Using.multiple rows of snow fences, sometimes double in height, may be needed in areas that get large and prolonged amounts of snow (e.g., ski resorts), or where the eave to valley length is long, or where the slope is very steep.  Each increases the shear loads.

Designing a Snow Retention System

Snow retention systems need to be engineered, not guesstimated! Use online models to assist with designing snow retention devices. Input your snow load, roof slope, panel width, roof length (measured horizontally), overall width of the roof area, and the manufacturer and panel type. These inputs are needed to adequately engineer a snow fence assembly.  And remember, the snow loads are transferred from the fence to the panel seams, then to the panel clips and to the deck/structure.  The entire load path needs to be designed to handle the snow load.  Here is one model: http://www.s-5.com/calculator/index.cfm

For more tips on designing a snow retention system, read “The Art of Properly Specifying Snow Retention Systems.”

Designing a metal roof for snow is a mix of logic, experience and engineering. We can design roofs in snow because of our everyday observations of roofs with snow on them. Stay observant; design well.

Snow and Metal Panel Roofs: Part I

It’s February; winter storm Jonas happened last month. Snowstorms will continue to occur, and heavy snowfall can have many negative effects on roofs. What should you consider when designing a roof in snow areas, especially those with high snow amounts?

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What to Consider when Building Metal Roofs

Roofs on buildings in snow areas—from a structural capacity point of view—can be designed to be any low-slope or steep-slope roof system. Roof structures can be designed and built to accommodate any anticipated snow loads. From a weather-protection point of view, snow buildup on a roof can be problematic. The extra load and the risk of leaks are not desirable; however, keeping snow on a roof is often the acceptable way to deal with it.

Roof Slope

Unquestionably, the slope of the roof matters when it comes to snow staying on or sliding off. Once a roof slope gets to be about 45 degrees (i.e., 12:12), slope becomes the overriding factor for sliding snow. The amount of snow and the roof type also matter. From a designer’s perspective, there are also a number of localized issues to consider when designing for snow on roofs.

Snow Density

The amount and density of snow also matters. More snow means more weight. More weight means a greater sliding force down (along) the slope of the roof. On slopes less than 45 degrees (e.g., 6:12 to 9:12), a low coefficient of friction (such as on smooth pan metal panels) means less resistance to sliding. Striations and embossing add a small 3D profile and improve the resistance to sliding, especially if they run transverse to the slope.

When heavy, dense snow slides it can pack a punch. Such snow sliding down a roof can shear off exhaust vents; therefore, rigid vent pipes are needed, along with a secure method of attachment. Further, installing vent pipes as high up on the slope as possible reduces the amount of potential shear load. Consider the potential load on a vent pipe that’s 5 feet from the eave with a 40-50-foot eave-to-ridge length! Reverse that and most of the load goes away.

Roof Material Type

Material type and surface color make a difference, specifically a roof’s emissivity. Metal roofing absorbs heat more quickly and radiates heat more effectively than most other roofing materials. Darker colors enhance this effect. Even with as much as 3 to 5 inches of snow, UV light passes through it; less light passes the denser the snow. (The proof: solar energy panels [photovoltaics (PV)] work when covered in some snow.) This effect only happens on sunny days, and is most effective on south-facing roof areas. If there is heat loss from the building up through the roof, the heat will help melt the snow at the roof/snow interface. This creates a potential for sliding snow.

In part II of this blog, I’ll discuss the logic, experience and engineering that goes into designing a metal roof for snow. In the meantime, learn how to properly install snow retention devices, and watch how a New Jersey home heats and cools itself by gathering snow and rainwater.

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