Tag Archives: Steel

Specifying Structural Framing Systems


Photo © Amy Numbers

by Stephen Metz, PE, LEED AP
Many factors come into play when designers specify structural framing. There are so many criteria, sometimes there is no absolute answer as to which framing system would perform best. At the same time, the interests of various parties must be served, meaning the final selection does not always rest with the structural engineer.

Despite the number of variables influencing the design team’s choice of a structural system, there are a few major consistent considerations from project to project. These variables can include:

  • building code requirements;
  • aesthetics;
  • owner preference;
  • functional requirements;
  • spans and/or structural depth limitations;
  • cost; and
  • schedule.

Building code requirements
A building’s fire resistance rating—the number of hours for which treated structural members can withstand a standard fire resistance test—is a measure influencing structural design. International Building Code (IBC) Table 601 provides the fire-resistance ratings of a building’s primary structural elements and establishes five classifications for construction types—Type I requires the highest fire-resistance ratings for its structural elements, and Type V requires the lowest. (See Figure 1.)


Figure 1: This shows the classifications of construction types. Image courtesy SMBH

Steel, concrete, masonry, and fire-retardant-treated wood are the only structural materials allowed in Type I and II construction, which both require materials to be non-combustible. If a fire rating is required, structural steel cannot remain unprotected. Fireproofing—typically by spray-applying a cementious fireproofing material, coating with intumescent paint, or encasing in concrete—is needed to achieve the required rating. Masonry and concrete achieve the ratings with little to no additional considerations, though with the latter, the cover for the reinforcing steel needs to be increased beyond its typical depth to achieve higher ratings.

When designing to meet the building code, engineers have to pay attention to many tangential items. For example, IBC may require testing of an actual wall assembly to National Fire Protection Agency (NFPA) 285, Standard Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-load-bearing Wall Assemblies Containing Combustible Components, if it is designed to have combustible materials (e.g. certain kinds of insulation or vapor barriers) within its otherwise non-combustible walls.

Aesthetics and owner preference
Aesthetic considerations are a top priority for many building types and a structure’s material palette signals its overall quality and design sensibility. While one basic material may not be objectively ‘better’ than others, a designer often has an aesthetic goal in mind dictating the choice of materials right down to the structural system. Similarly, owners often have a preference for one structural system over another—however, they may not be basing their opinion on complete information. For example, a building owner may want to use a wood structure for a six-story building; but IBC will not allow a wood structure taller than five stories. Either way, a collaborative approach should be taken between structural engineers, the owner, designers, and other stakeholders to ensure everyone’s priorities are addressed.

Functional requirements
A building’s use or geographic location may dictate a given structural system. Most notably, buildings located in tornado- or earthquake-prone locations require special engineering and must meet particularly stringent codes. Care should also be taken to identify whether a structure is likely to experience vibration. For example, buildings located near railroad tracks may need to be designed with special considerations if the occupants or equipment within the building are susceptible to vibration.

In extreme cases where a building will experience large amounts of vibration, studies of the structure’s natural vibration characteristics can be done to ensure there is no damage to the building. In rare circumstances, the induced vibration can have the same frequency as the structure’s natural resonant frequency, which can cause harm to the building.

Building structures must be designed as not to excessively deflect, damaging the materials and being noticeable to the occupants. IBC provides limits on floor and roof deflections and allowable lateral drift of a building. Typically, floor deflection is limited to the span in feet divided by 360 (l/360), with a maximum of 25 mm (1 in.) allowed. Roof deflection is the same limit. Lateral drift is typically limited to the building’s height in feet divided by 400 (h/400). In some circumstances, equipment or specialized occupancies will limit the deflection to less than what is typical.

Individual building types frequently have special needs when it comes to structural systems. For example, warehouses often require super-flat floors, to allow the facility’s equipment to properly function. Elevated super-flat floors require the supporting framing to be designed with strict deflection limitations so the floor stays within flatness tolerances when it is loaded. Building structures supporting heavy loads, such as equipment, require careful consideration of the actual equipment loads. Special attention has to be paid to any deflection limitations. It is also important to consider how the equipment will be put into its final location in the building.


Steel framing and precast concrete were chosen for the connector addition at the Ohio State University (OSU). Photo © Amy Numbers

Span and structural depth limitations
A building’s size or space requirements may entail the use of a given structural system. If a building needs large, column-free floor areas, the longer spans between columns results in deeper floor structures. Floor-to-floor height is always a driving force behind structural decisions. Increased heights cost more for materials and result in higher climate control costs over the life of the building, due to the increased volume.

Local zoning codes also place height restrictions on many building types, and a structure classified as a high-rise will have to comply with additional code requirements, involving an increase in cost. Buildings typically requiring low floor-to-floor heights are best framed with concrete two-way slab systems. This system is usually the thinnest structural system available. A conventional concrete beam and slab system will have similar depth to a conventional structural steel system.

Every building project has a budget, the question is, how generous is it? Some high-end buildings are designed around novel structural systems that showcase the creative possibilities of modern engineering. Some architects may rely on a uniquely sculpted building mass to convey creativity. These designs may require curved structural members, expansive horizontal and vertical interiors, or other complex structural systems integral to the building’s aesthetic. When this is the case, there will most likely be a bigger budget for the structural framing system.

Even for utilitarian buildings, however, the structure may not always be the place to save money. Sometimes investing more in the structural system will save money somewhere else in the project. For example, for one major high-rise, adapting the building’s column layouts in a way that would accommodate less expensive office furnishings was a worthwhile trade-off. Furnishings may seem like a minor expense or an afterthought to structural design, but on the scale of an office building housing hundreds of employees across multiple floors, this type of detail becomes particularly significant.

Typically, the structure costs between 15 and 30 percent of the total construction project. Therefore, if structural system costs increase by 10 percent, this only translates to a 1.5 to three percent rise in the building’s total construction cost.

North Bank Park4

An example of how the exposed structure in a building can be the aesthetic. Photo © Robert Baumann

As with cost, a project’s schedule can influence what kind of building structure is selected. One factor is the lead times necessary for procuring materials. A structural steel fabrication order may require two to four months to fill, while obtaining the materials to place concrete takes only days. However, for post-tensioned concrete structures, the cables and hardware, as well as the reinforcing steel, can take weeks to obtain. Precast concrete elements require two to four weeks to fabricate, as do wood trusses for wood-frame construction. These schedule constraints should be considered when selecting a system.

A retrofit case study
The aforementioned considerations apply to both new construction and renovation. Some of them, however, become particularly significant during a renovation. On the Ohio State University (OSU) campus, four towers in the university’s South Residential District were combined into two buildings through the construction of 11-story connectors. Each connector addition provides 164 new sleeping accommodations along with group learning and social spaces.

The original towers were constructed in the 1950s. All are based on the same floor plan and are constructed of reinforced concrete frames with brick masonry and limestone cladding. While building code requirements allowed for any Type II A construction (i.e. steel or concrete) in the new additions, the fact each addition had to connect two existing dormitories presented some challenges.

For aesthetic reasons, it was desirable to have the first floor be column-free. The structure also had to fit within the new room module. Perhaps the project’s most challenging aspect had to do with structural depth limitations; the existing dormitories had a floor-to-floor height that was only 2.8 m (9 ft 4 in.)—low by contemporary standards. New construction had to match this height. OSU expressed a slight preference for using concrete framing, as this already existed in the original structures. However, in this case scheduling concerns outweighed the owner’s desire to stick with concrete framing and the design team elected to go with a staggered steel truss system, which uses story-deep structural steel trusses that clear span the width of the building. The floor system uses hollow-core precast concrete spanning between the trusses.


This shows an example of large equipment loads that can induce large amounts of vibration into the structure, requiring special consideration when designing. Photo © Brad Feinknopf

The project’s construction schedule was too aggressive to go with a concrete framing system. OSU planned for the dormitories to be out of service for one school year; even with construction commencing at the beginning of a summer break, this left only 14 months in which to perform the work, so concrete framing for the 11-story additions could not be erected quickly enough to accommodate the timeframe. The advantage of using steel framing and precast concrete was that elements could be fabricated in the spring and arrive onsite as soon as the school year had ended in early June. The actual steel erection began within days after school ended.

Trusses are also space-efficient since they are more shallow than conventional framing. Steel trusses used in the OSU dormitory additions are the same depth, from the top chord to the bottom chord, as the structural depth of the existing buildings. Positioning of the trusses had to be coordinated with the room layout so the trusses would be located between rooms. Additionally, the staggered steel truss system fulfilled the requirement for a column-free first floor space. The truss system clear spans the entire building’s width, requiring columns only at the exterior walls.

While there are many variables influencing the choice of a structural framing system, a systematic approach—taken early in the project’s design—should lead to the selection of a system optimal for any given project. A collaborative approach between stakeholders further ensures everyone’s primary considerations are addressed in the final building design.

Stephen J. Metz, PE, LEED AP, BD+C, is the president/principal at structural engineering firm SMBH Inc. With more than two decades of structural engineering experience, Metz’s office and field experience includes material testing, construction inspection and land surveying, which contributes to his knowledge of the design and construction process. Further, his previous experience with a full-service architectural firm provides him with the skills required to produce well-coordinated construction documents. Metz has a bachelor’s degree in civil and structural engineering from the Ohio State University (OSU). He can be contacted by e-mail at smetz@smbhinc.com.

Walking the Walk

Energy distributor makes efficiency top priority

A clear-span steel structural system was chosen to accommodate heavy equipment at the Washington Electric Cooperative project in Marietta, Ohio. A standing-steam metal roof system was specified to provide relief from the leaks of the former facilities. Photos © D.A. Fleischer Photography

A clear-span steel structural system was chosen to accommodate heavy equipment at the Washington Electric Cooperative project in Marietta, Ohio. A standing-steam metal roof system was specified to provide relief from the leaks of the former facilities.
Photos © D.A. Fleischer Photography

By Kevin Hutchings

Maximizing energy efficiency is a key concern on virtually every new commercial construction project. When the construction happens to be for the electric provider itself, it is easy to understand how the priority takes on even greater importance. This was the case for Washington Electric Cooperative, an energy distributor located in Marietta, Ohio.

The company had been operating for years out of three separate facilities, serving nearly 10,500 customers in six counties. After five years of site planning and land acquisition, it was ready to consolidate under one roof, adding both operational and administrative efficiencies in the process.

Chief among Washington Electric’s goals with its new facility was the desire to build to Leadership in Energy and Environmental Design (LEED) certification, underscoring its commitment to energy efficiency. Additionally, the company had a vested interest in using a local company for construction.

Persistence pays off
Washington Electric approached a local builder for a design-build solution. However, since the project was receiving financial assistance from the local Rural Utility Service (RUS), a government agency, the project was required to go through a bid process. After nine bidders and 90 days, local company Mondo Building & Excavating was chosen for the project.

The building was originally designed to pursue entry-level LEED certification. Striving for a higher goal of Silver would have required enhancements specific to such areas as water runoff and recycling—issues not germane to Washington Electric’s core business.

“We really wanted to do it right when it came to the energy side,” says the company’s CEO Ken Schilling. “We wanted to walk the walk with everything from solar panels to high-efficiency water heating, geothermal heating and cooling, and high-efficiency windows.”

In an effort to decrease the amount of artificial light needed and control heating costs, all offices were located on the outer perimeter, and a clerestory runs the entire length of the facility.

In an effort to decrease the amount of artificial light needed and control heating costs, all offices were located on the outer perimeter, and a clerestory runs the entire length of the facility.

Bringing more natural light inside the building also played a key role in LEED certification. For instance, all of the offices were located on

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the outer perimeter, enabling inclusion of windows. This allows the building to gain more heat from the sun during the winter, as well as reduce the energy required for electrical lighting.

Kevin Guiler, project manager, explains how another design element provided a flood of natural light.

“We added a clerestory that runs the entire 61-m (200-ft) length of the facility. It has 762-mm (30-in.) windows that add daylight and help conserve energy by reducing daily lighting needs,” he said.

The clerestory also features a gable-type window on the front facing to give it an attractive, finished look.

The new facility is 2787 m2 (30,000 sf)—including 1003 m2 (10,800 sf) of office space and 1783 m2 (19,200 sf) of space for operational support. At any given time, bills are being processed in the front area, while bucket trucks and track diggers are maneuvering in the building’s back area.

With such a broad range of activities happening inside, it was critical to find a cost-effective building design that could also be versatile.

A clear-span steel structural system was used to construct the facility, with 7.6-m (25-ft) bays in the back to accommodate the heavy equipment frequently moving in and out of the building. While the company’s needs did not call for a clear-span frame, the structural system did provide the flexibility necessary to optimize all work processes inside the facility.

The building’s roof features a standing-seam metal roof system. This was a change from the existing buildings the company was operating from—all three were experiencing leak issues. Schilling recalls the issues of the old administration building in particular.

“It was a brick building built around 1963, and it had a flat roof,” he says. “It leaked around the rooftop heat pumps and was giving us fits.”

The roof system provided a proven weathertight solution. The assembly’s efficiency, long life cycle, and recyclability attributes helped contribute to the sustainability of the new facility as well.

Smooth construction
Despite running into a few unforeseen challenges, including some tricky excavation work around a high-pressure gas line outside the building, the overall construction process itself went smoothly.

“Our concept was we wanted a simple building, but one that was very energy efficient and functional,” says Shillilng. “We were determined to get a lot of bang for our buck and have a building that will be useful for the next 50 years. “

CROPKevin Hutchings has been the training manager for Butler Manufacturing for 15 years. He is responsible for product, builder management, and sales training. Hutchings joined Butler as an order technician for the buildings division and in the retrofit roof group, where he gained substantial experience in metal roof design and detailing. He has also served as project services manager for the roof division of Butler, managing a number of large and complex retrofit roof projects. Hutchings can be contacted by e-mail at jkhutchings@butlermfg.com.

A Paradigm Shift in Specifying Temporary Structures

All images courtesy Mahaffey Fabric Structures

All images courtesy Mahaffey Fabric Structures

by Beth Wilson

Clear-span aluminum structures and temporary steel buildings have advanced over the years. Knowing when to use them is a skill worth mastering for construction specifiers, procurement professionals, and facility managers. Familiarity with specific spaces, and knowing the assemblies’ framework of costs and benefits, may also help designers and specifiers incorporate them into their own sites and make optimal recommendations.

For those who have been in the trade for a while, there may be a natural aversion to temporary structures. Historically, these options have been expensive, constrictive, and almost universally required functional concessions on some level. Up until about a decade ago, if space was needed immediately or in the near-term for occupancy of less than five years, there were not a lot of reasonable options (Figure 1).

Traditional options for occupancies of less than five years.

Traditional options for occupancies of less than five years.

New options
Since the turn of the century, there have been exponential improvements in the strength, quality, versatility, cost-effectiveness, and energy efficiency of clear-span aluminum and temporary steel structures. The result has been a paradigm shift in the consideration of temporary space.

Although modular trailers have come a long way in form, function, and versatility, they are generally designed for office and classroom use and are not typically scalable without creating a village. When larger, contiguous, weather-tight warehouse or workspace is needed, the two best options are industrial clear-span tents and temporary steel buildings.

Clear-span structures
There are several classes of clear-span structures that can be installed onsite in less than one week, outfitted with utilities and a full range of access, safety, and security features. Also called ‘industrial tents,’ these aluminum systems include stretched fabric.

These are lightweight aluminum structures offering both durability and versatility. Typically, they are deployed for up to six months at a time in temperate climates where sun protection is more of a priority than severe weather, such as petrochemical facilities and oil fields in Texas and Louisiana. A structure rated for a wind speed of 144 kph (90 mph) is more than sufficient to protect contents and occupants from summer thunderstorms. Further, these structures can be relocated fairly easily, making them a good choice if site flexibility is an issue.

Interior view of final strucutre deployment around existing nuclear facilities at Grand Gulf Nuclear Power Station in Port Gibson, Mississippi.

Interior view of final strucutre deployment around existing nuclear facilities at Grand Gulf Nuclear Power Station in Port Gibson, Mississippi.

If a more substantial structure is needed in harsher climates for at least three months, an aluminum box beam system is a better option. These can withstand winds up to 209 kph (130 mph) and snow loads of up to 146 kg/m2 (30 lb/sf).

For hangar-type applications or environmental remediation sites in snow country, a peaked arch structure is the best option, as it is engineered with a slope for snow shedding. This is a light-weight structure, which can also be moved with ease.

Temporary steel buildings
Similar to clear-span aluminum systems, temporary steel buildings offer the key benefits of a permanent structure without the long ‘planning/building’ wait and long-term commitment to real estate. They are designed with the aggregate of state and local building codes in mind. Most, if not all, are compliant with American Society of Civil Engineers (ASCE) guidelines, International Building Code (IBC), and California Fire Marshall Code (equal to or exceeding the standard issued by the National Fire Protection Association [NFPA]). Given these considerations, obtaining permits and approvals is usually expedient. Also, because clear-span structures have no interior uprights to impede usable space, flexibility is maximized.

Perhaps most compelling in the consideration of temporary steel buildings is their low upfront and monthly cost over a three-year term when compared to plan/build and lease options. Particularly when one considers lease and plan/build expenses start well before the space is ready, it is worth noting the cost per square meter for time-in-use during the first year (Figure 2).

Time-framing the decision
There are two primary questions that frame the ideal spot for using clear-span aluminum structures and temporary steel buildings: How soon is it needed, and for how long?

A clear-span aluminum structure can easily meet an immediate need and is typically durable enough to remain installed onsite for up to two years. Temporary steel buildings can also be onsite quickly—21 to 30 days in most cases—and serve a three- to five-year term. The structures can certainly last longer, but it becomes a less economical choice.

If the need is not immediate, and the term is more than five years, then leasing, purchasing, or building offsite space become better options (Figure 3).

While some larger organizations have entire departments dedicated to property planning, investment, and management, others choose to stay focused on core businesses and avoid the complexities of long-term real estate entanglements. The latter is an ideal scenario for temporary structures. Also, because temporary buildings are considered an operating expense as opposed to a capital expense, many organizations see tax benefits in their use. Additionally, the overall cost for space needed for five years or less can be as much as 81 percent less per square meter.

Finally, both aluminum and steel clear-span structures can generally be installed without a poured or pieced foundation. A dry, level lot, or a paved parking lot, are all that is needed for installation. This is a big factor on the shortened installation timeline, and also exempts temporary buildings from property taxes in most jurisdictions.

Various costs associated with temporary steel buildings compared with other routes.

Various costs associated with temporary steel buildings compared with other routes.

Energy efficiency, sustainability, and LEED
Previously, the term ‘temporary’ was used to infer flimsy and disposable. With advances in materials and engineering, temporary structures can be designed to be energy-efficient, and their elements are generally reusable and recyclable. A temporary building may not be certified under Leadership in Energy and Environmental Design (LEED) on its own, but employing one may help qualify a larger project for points. Suitable vendors should obtain materials from recycled sources, repurpose its structures (or elements thereof), and recycle materials at the end of their useful life. For example, a manufacturer targeting LEED accreditation could use a temporary structure to expand a production facility, as opposed to building a larger permanent facility.

Specifically, potential LEED credits include:

  • Materials and Resources (MR) 1.1, Building Reuse–Maintain Existing Walls, Floors, and Roof;
  • MR 1.2, Building Reuse–Maintain 50% of Interior Non-structural Element;
  • MR 2, Construction Waste Management—if a vendor can prove elements of a structure will be recycled at the end-of-life; and
  • MR 3, Materials Reuse—if the structure used has been erected before.

In addition to LEED benefits, many vendors now offer energy-efficient lighting and HVAC options, as well as insulated wall panels ranging in R-value from R-13 to R-30. These buildings are often used for safety and craft ‘tents’ in the harshest of summer and winter climates, offering refuge for workers on remote sites. The cost of utilities in operating these is greatly reduced from the tents of a decade ago.

Utility and safety are essential
The U.S. Army Corps of Engineers (USACE) frequently makes use of clear-span structures and temporary steel buildings in disaster relief and recovery efforts, as well as for environmental remediation. The requirements for these projects are frequently as rigorous as a permanent structure, including wind and weather, energy efficiency, utilities, security systems, and custom interior finishes. Sometimes the only difference is the timeframe—onsite immediately, or in less than a month.

The safety and professional certifications of a chosen vendor should be considered when choosing a temporary structure for a site. Often sites have specific requirements, such as:

  • Transportation Workers Identification Credential (TWIC);
  • Defense Information Systems Agency (DISA);
  • Occupational Safety and Health Administration (OSHA); and
  • National Center for Safety Initiatives (NCSI).

On May 22, 2011, an Enhanced Fujita (EF) 5 tornado hit the town of Joplin, Missouri. Public infrastructure was leveled, including an elementary school with a large multi-purpose room (i.e. the cafeteria, gym, and auditorium) that also served the larger community for meetings and events. Replacing such a core asset for the town became a priority for the USACE team, and so a fully functioning gymnasium for the elementary school was installed. The 20 x 30-m (66 x 100-ft) community-uniting facility was bigger and stronger than the multipurpose room that stood before the storm. The steel I-beam construction with vertical steel sidewalls and pre-stressed roofing material provided a solid structure around which the community could rebuild itself.

Weighing options for temporary structures versus leasing, purchasing, or building offsite space. Images courtesy Mahaffey Fabric Structures and Boomerang Buildings

Weighing options for temporary structures versus leasing, purchasing, or building offsite space. Images courtesy Mahaffey Fabric Structures and Boomerang Buildings

Bringing a building to you
In late 2011, integrated energy company Entergy, was up against a federal deadline to update the nuclear cores at Grand Gulf Nuclear Power Station in Port Gibson, Mississippi. The cost of moving the reactor units to a controlled work environment would have been astronomical.

A custom structure was built over the reactors in place. In less than three weeks, a 25 x 40-m (82 x 132-ft) building was erected. A portion of the building had 6.4-m (21-ft) uprights to accommodate the use of heavy equipment inside, while the balance had 4.8-m (16-ft) sidewalls. The two were merged around an existing security fence and plantings, avoiding the need to alter the site, which would have required a lengthy and involved permitting process.

Two additional structures were also used. One tent was used for meals and safety meetings for the project laborers and a second was created to shelter the nuclear waste disposal process. When the old cores were replaced with the new more efficient ones, an aluminum temporary structure provided a controlled environment for the load-out from the tanks.

The plant was shut down during the changeover, making time of the essence. This was an ideal application of temporary structures, which provided the required workspaces on-demand, while minimizing logistics and expenses.

Interim solutions
For most of the 20th century, the fire station at the Port of Los Angeles was a unique landmark—a towering covered boathouse that protected the expensive vessels and equipment the crews used to fight fires in the port. In 1986, the boathouse was demolished, making way for the development of a new cargo container complex.

This is the interior of the temporary building serving as school gymnasium in Joplin, Missouri in May 2011.

This is the interior of the temporary building serving as school gymnasium in Joplin, Missouri in May 2011.

The Ralph J. Scott, a 30-m (100-ft) fireboat commissioned in 1926, was then moved to an open water slip in the port. In 1989, it was declared a National Historic Landmark, but, left to the weather, the elements took their toll. Fireboat #2, as it was also called, was retired in 2003. The weather contributed to the deterioration, and there were few laborers left with the skills to maintain the hand-riveted hull. The fireboat sat on a cradle behind the award-winning Station 112 in the Port for many years awaiting a visitor-friendly facility and the funding and manpower for the restoration. An interim shelter to prevent the vessel’s further deterioration was needed, as well as an enclosure where the restoration of the Los Angeles Fire Department’s (LAFD’s) longest-serving apparatus might commence.

In early 2013, a plan was delivered to the Port and the onsite building erection was completed in a total of 21 days. The Ralph J. Scott now sits in a custom building at the Port of Los Angeles—a 15 x 36-m (50 x 120-ft) structure with custom 10.67-m (35-ft) sidewalls and a 32-degree roof pitch. Special eave and gable framing support the taller sidewalls while maintaining a clear-span working space in the center to accommodate the ship’s shape.

From school gymnasiums to nuclear reactors to historic sites, temporary buildings offer a range of flexible, durable, and safe options that are both cost-effective over the short term and energy-efficient in the harshest of climates. While planning future projects, it is critical to ask the ‘how-soon’ and ‘how-long’ qualifying questions to determine whether a clear-span aluminum structure or temporary steel building should be considered.

Beth Wilson is the marketing manager for Mahaffey Fabric Structures—a vendor for the U.S. Army Corps of Engineers (USACE), Exxon, S&B Engineers and Constructors, the U.S. Army, and Turner Construction. She is a board member for the Memphis Regional Chapter of the U.S. Green Building Council (USGBC) and has been published in more than 20 industry publications. Wilson was instrumental in promoting Mahaffey’s sustainable Boomerang Building product line and providing guidance on building components made from recycled material with the goal of achieving LEED points. She is also an accomplished presenter and mentor for those seeking CMP credit with the USGBC and the Green Building Certification Institute (GBCI). Wilson can be contacted by e-mail at beth@boomerangbuildings.com.

Putting a Fresh Face on Historical Façades: Project teams

Hallidie Building Project Team
Owners: Edward J. Conner and Herbert P. McLaughlin
Owner’s Representative: The Albert Group Inc.
Architect of Record: McGinnis Chen Associates
Preservation Architect: Page & Turnbull Inc.
General Contractor: Cannon Constructors
Surface Preparation Shop Coatings and Field Applicator: Abrasive Blasting & Coating (ABC) Inc.
Specialty Engineering and Testing: Professional Service Industries Inc.
Coating Consultants: Amos and Associates

ZCMI Project Team
Owner: City Creek Reserve Inc.
Engineer, Surface Preparation, and Primer: Historical Arts & Casting Inc.
Architect: Hobbs & Black
General Contractor: Jacobsen Construction Company Inc.
Field Applicator: Daniels Painting
Coating Consultants: Protective Coatings Intermountain Inc.
Miami County Courthouse Project Team

Owner: Miami County
Architect: John Ruetschle Associates Inc.
Engineer: Historical Arts & Casting Inc.
Construction Management Team: Cast Iron Restoration Management
General Contractor: Shook Construction Company
Shop Applicator: Brian Painting Company
Field Applicator: E.B. Miller Company
Coating Consultants: Ohio Coating Consultants

To read the full article, click here.

Putting a Fresh Face on Historical Façades

Photo courtesy Robert A. Baird/Historical Arts & Casting Inc.

Photo courtesy Robert A. Baird/Historical Arts & Casting Inc.

by Jennifer Gleisberg

Across the country, communities are preserving and restoring historically significant architectural façades recognized for ornamental sheet metal and cast-iron features such as colonnades, domed roofs, cornice sections, dentil blocks, frieze panels, and pendants. Many historical façades dating back to the second half of the 19th century have been neglected and damaged from impacts, moisture intrusion, corrosion, or flawed castings.1

Water intrusion resulting from the absence or failure of adequate waterproofing systems often leads to deterioration of not only the structural steel, but also the clips, brackets, and fasteners used to attach ornamental components. Fissures, or pitting in cast iron or other decorative metal pieces, can also trap moisture and airborne corrosive materials, causing oxidation or rust to occur over time.

Restoring these landmarks to like-new condition requires craftsmanship, technical expertise, and high-performance coating systems that comply with demanding standards for aesthetics, durability, and resistance to corrosion and ultraviolet (UV) light.2 This marriage of skill and technology is especially evident in the three projects highlighted in this article:

  • San Francisco’s Hallidie Building;
  • Zions Cooperative Mercantile Institution (ZCMI) cast-iron storefront in Salt Lake City, Utah; and
  • the cast-iron domed roof façade of the Miami County Courthouse in Troy, Ohio.

The Hallidie Building’s curtain wall
After 2.5 years of remediation work, the iconic Hallidie Building’s main façade was complete. Architects involved with the project were McGinnis Chen Associates and preservation architects, Page & Turnbull. Additional specialists involved with the restoration included a materials scientist, sculptor, testing agency, structural engineers, curtain wall consultant, and coatings consultant.3

Named for Andrew S. Hallidie, the inventor of the cable car and a regent at the University of California, the building was listed in 1971 on the National Registry of Historic Places and the San Francisco Historic Landmarks and Districts. Originally designed by Willis Polk and constructed in 1917–1918 by the University of California, the building is noted for its glass curtain wall façade, which was considered unique for its time, but has now become a common element in modern architecture.4

The building is described in San Francisco: Building the Dream City, in the following passage:

The glass façade was hung, curtain like, away from the actual structural frame of the building, in a separate frame of elaborate cast iron, with ornate fire escapes at either side. The ornamental iron fretwork relieves the cold severity of an all-glass wall, and the result is highly decorative.5

Annie K. Lo, LEED AP, project manager for McGinnis Chen Associates, was responsible for evaluating, labeling, photographing, and documenting each piece of the building’s curtain wall, frieze panels, ornamental balconies, and fire escapes. She explained the uniqueness of the glazed curtain wall at the time of construction is significant. Considering available technology in 1918, Polk was inventing something, rather than using an example to model after.6

Numerous challenges were encountered with the Hallidie Building’s water-damaged structural steel, corroded frieze panels of stamped zinc, and ornamental fire escapes and balconies. At the time of construction, sealants or flashing with adequate waterproofing were not available. Also, the design did not support metal expansion and contraction normally required in a curtain wall.

Phase I of the restoration involved removal, repair, and reinstallation of approximately 735 sheet metal and railing components for the ornamental balconies and fire escapes, along with 360 windows around the perimeter of the curtain wall façade. Phase II of the project, completed April, involved the removal, repair, and reinstallation of the remaining 153 windows in the curtain wall.

For the project team, getting to Phase I was a challenge, explained Lo.

“We started working with the city and the Historic Preservation Commission on obtaining approvals to remove the metal pieces since this was a salvage and disassembly project for a notable landmark building,” she said. “Each piece had to be tagged and given an identification number so it could be tracked throughout the repair process and reinstalled on the building.”

Originally, the project’s architects envisioned restoring the frieze panels by making spot repairs to severely corroded sections. This repair methodology was changed after the existing lead coatings were removed and the severity of damage to the panels was determined. The back side of the panels was reinforced with a spray-applied layer of fiberglass, which enabled more of the original historic material to be salvaged.

More than 90 years of exposure to water caused damage to the structural steel and decorative metal of the Hallidie Building façade. Photos courtesy Annie K. Lo/ McGinnis Chen Associates

More than 90 years of exposure to water caused damage to the structural steel and decorative metal of the Hallidie Building façade. Photos courtesy Annie K. Lo/ McGinnis Chen Associates

Another change involved the method used by the coating applicator to remove the multiple layers of lead paint that had built up over decades. Early in the project, it was envisioned the paint would be removed by dipping pieces into a chemical stripping solution. However, this method proved too slow and did not provide the cleaning needed to apply a zinc-rich, aromatic urethane primer.

Due to the fragile and thin condition of ornamental cornice sections, dentil blocks, frieze panels, and pendants, these components were prepared in accordance with Society for Protective Coatings/NACE International–The Corrosion Society (SSPC-SP6/NACE) No. 3, Commercial Blast Cleaning, prior to the application of the primer. Window frames, window sashes, metal grates, and railing sections were prepared in accordance with SSPC-SP10/NACE No. 2, Near White Blast Cleaning, before priming with the same zinc-rich coating.

Structural steel used to support the ornamental balconies was so badly corroded from water infiltration it could not be salvaged or reused and had to be completely replaced.

Removal of ornamental metal was carefully monitored for compliance with environmental regulations, in accordance with Section 02085, Federal and State Occupational Health and Safety Administration (FED-OSHA) 29 Code of Federal Regulations (CFR) 1019, 1025, and California-OSHA under Title 8, CCR 1532.1, which relates to the proper capture and disposal of lead-based paint.

All surface preparation and paint removal was performed in blasting chambers offsite. The exterior coating system for both ornamental metal and structural steel consisted of a spray-applied zinc-rich primer, an aliphatic urethane intermediate coat, and a fluoropolymer topcoat in both satin and semi-gloss finishes.

The coating system was selected to achieve the highest level of performance in terms of color retention and longevity. Keeping the associated costs in mind, the durability and lifespan of the coating system was an important concern. A zinc-rich primer offering a high level of corrosion protection on bare metal was specified for the project. When this is applied with a proper intermediate coat, additional corrosion protection is attained.

Fluoropolymer topcoats offer aesthetic performance, gloss retention, and protection against UV light and climate conditions. The coatings were custom-matched to the building’s original colors. The project’s preservation architectural firm conducted a coating analysis that involved scraping down to the original first and second coatings and matching them to a Munsell color card, which was then provided to the coatings manufacturer.

Blue and gold were the original colors used on the building and the coatings created through the color match were accurate. Originally, a gold coating resembling true gold leaf was used on ornamental sheet metal and designers were able to replicate this. Once the ornamental metal pieces were reinstalled onto the curtain wall, coatings were used to touch-up welds and scratches.

Early this year, the Hallidie Building project was named winner of the Charles G. Munger Award at the annual Structure Awards sponsored by the SSPC. The award is presented to an outstanding industrial or commercial coatings project demonstrating longevity.7

This is the Hallidie Building before its architectural façade restoration.

This is the Hallidie Building before its architectural façade restoration.

The Hallidie Building is one of the world’s first glass curtain-wall buildings. Photo © Sherman Takata, Takata Photography

The Hallidie Building is one of the world’s first glass curtain-wall buildings. Photo © Sherman Takata, Takata Photography

Restoring the ZCMI façade
Recognized as one of the earliest department stores in the nation, Zions Cooperative Mercantile Institution was founded by Brigham Young in 1868. The structure’s three-story, classical cast-iron façade was constructed in three separate phases, beginning with its center section in 1876, followed by an extension to the south in 1880, and a north addition in 1901. The façade was placed on the National Register of Historic Places in 1970 and was subsequently listed on Salt Lake City’s historic register.8

Cast-iron façades were popularized throughout the second half of the 19th century due to their fire-resistant properties and ability to replicate sandstone and limestone. In addition to providing structural support to upper floors, cast iron also allowed large display windows for merchandise, allowing light into the building’s interior.9

In 1971, plans for a new downtown mall had called for demolition of the original building, including its cast-iron façade. A coalition of the Utah Heritage Foundation and community preservationists was successful in saving and restoring the façade to become part of the ZCMI Center Mall. Restoration architect Steven T. Baird was enlisted to develop procedures for dismantling, reconditioning, and reconstructing the façade from 1974 to 1976. Working primarily out of his garage, Baird is credited with creating the model for other cast iron renovation efforts across the country.10

The 23 x 43-mm (75 x 140-ft) ZCMI façade is now attached to the west face of Salt Lake City’s new Macy’s department store. [CREDIT] Photo courtesy Robert A. Baird/Historical Arts & Casting Inc.

The 23 x 43-mm (75 x 140-ft) ZCMI façade is now attached to the west face of Salt Lake City’s new Macy’s department store. Photos courtesy Robert A. Baird/Historical Arts & Casting Inc.

More than three decades later, the company owned and operated by Baird’s sons—Historical Arts and Casting Inc.—was commissioned to restore the façade a second time as part of the mixed-use redevelopment project. Today, the landmark façade fronts the west face of Salt Lake City’s new Macy’s department store.11

Measuring 23 x 42 m (75 x 140 ft), the façade consists of cast-iron colonnades with 63 bays for windows and openings, a cornice section made of galvanized sheet metal, and thousands of mechanically fastened ornate castings. For both restoration projects, each component was carefully numbered, cataloged, and moved offsite for reconditioning or replacement.

Restoring historical cast-iron façades like ZCMI presents major challenges. Cast iron’s ability to replicate stone was enhanced by mixing sand into paint, which was then applied in thick coats to the casting. Locating fasteners under several layers of old paint was a challenge during the first restoration in the 1970s. Additionally, many of the façade’s original cast-iron components were severely deteriorated due to moisture penetration and had to be recast.12

The preferred method for removing old paint from cast iron is blast-cleaning in accordance with SSPC-SP6/NACE No. 3, followed immediately by the application of a primer to prevent surface rust. Since most old paint found on historic cast-iron façades contains lead, blasting debris must be captured and disposed of in accordance with U.S. Environmental Protection Agency (EPA) regulations (e.g. 40 CFR Subchapter 1, “Solid Wastes.”13

When surface preparation uncovered pitting or other imperfections in the cast iron, a surfacing epoxy to recondition the surface, followed by zinc-rich aromatic urethane, and intermediate epoxy primers that doubled as a field-applied tie coat, were used. Structural steel used to secure cast-iron components to the building was blast-cleaned and primed by the fabricator with a zinc-rich aromatic urethane primer.

The façade’s galvanized-metal sections were prepared in accordance with SSPC-SP1, Solvent Cleaning. Abrasive blasting was originally tried, but the sheet metal was too thin; therefore a chemical stripper on the metal was used and it was then pressure-washed.

The cornice sections were shop-primed with a polyamide epoxy coating, followed by a finish coat of high-solids fluoropolymer coating specified for its ultraviolet (UV) light stability and durability. Four custom colors were specified, including a metallic gold that mimicked 24-karat gold leafing. An acrylic polyurethane metallic clearcoat was applied over the metallic gold finish wherever it was used.

The cast-iron façade on Zions Cooperative Mercantile Institution (ZCMI) consists of thousands of ornamental components assembled together on columns.

The cast-iron façade on Zions Cooperative Mercantile Institution (ZCMI) consists of thousands of ornamental components assembled together on columns.

During reassembly and the application of field coatings the façade was surrounded by scaffolding and enclosed to help control environmental conditions. Tie-coats, fluoropolymer finish coats, and gold accent finishes were brush-, roller-, and spray-applied to the cast-iron colonnades and ornate castings then reattached to the façade by screws using detailed drawings as a guide.

Approximately 2300 work hours and 1892 L (500 gal) of coatings were needed to complete the field coatings and installation, which was completed in the spring of 2012.14

Bringing order to the Miami County Courthouse
The decorative exterior of the Miami County Courthouse in Ohio, constructed between 1885 and 1888, was also restored. The original Greco-Roman design by Joseph Warren Yost featured four corner domes, a central dome, and four pavilions built of cast-iron cladding over riveted iron frameworks.15

After nearly a century, the building’s decorative cast iron had severely corroded due to water intrusion, which threatened the building’s interior courtrooms that had been renovated in 1982. In 1989, an architectural firm was contracted to conduct a condition survey that included a preliminary specification for what would eventually become the largest restoration of cast-iron construction in the country.16

In 1995, the county retained a construction management team to oversee the project. The following year, a local construction company was awarded the primary restoration contract, which called for dismantling and restoring the cast iron from the building’s five domes and four pavilions. The contract also called for replacement of the building’s slate roof, copper flashing, windows, exterior lighting, copper statues, and clock tower.

Before cast-iron components could be removed, more than 18,143 kg (40,000 lb) of pigeon waste and other debris was taken from the belfry. The disposal of this material followed the same guidelines as removal of asbestos or lead. 17, 18

Rather than prepare the cast iron for recoating onsite, it was prepared, primed, and given an intermediate coat offsite. Once the material was returned and reinstalled, the field touch-up and finish coats were applied.

Coating consultant Dan Haines compared the removal of cast-iron components to “an architectural dig”—each piece of the cladding was cataloged using a numerical coding system identifying the exact location it needed to be reinstalled.

Crews worked from scaffolding and used an exterior elevator lift to move more than 15,000 cast-iron pieces, which were dismantled and taken offsite in phases to be reconditioned or replaced. Historical Arts and Casting was responsible for recasting more than 50 percent of the severely corroded cast iron, requiring more than 700 patterns to be manufactured.19

It was determined a lack of sufficient waterproofing led to the failure of the decorative cast iron on the courthouse, so replacement pieces were molded with flanges and lap joints enabling moisture to run off rather than collect on the surface. Vertical and horizontal joints were caulked with a silicone system to prevent water penetration and adhesion testing was conducted to verify the coating system’s ability to bond to the prepared cast-iron components.20

Both replacement parts and reusable cast-iron components ranging in weight were prepared in accordance with SSPC-SP6/NACE No. 3, Commercial Blast Cleaning, and shop-primed with a zinc-rich aromatic urethane primer. They also received a shop-applied intermediate coat of polyamide epoxy coating.

Structural iron was cleaned and field-coated with a high-build modified polyamidoamine epoxy coating. Once the shop-primed cast-iron cladding was reinstalled, it received a field-applied coat of a light gray aliphatic acrylic polyurethane topcoat, followed by a urethane clear coat. 21

Cast-iron cladding that covered the domes and pavilions of the Miami County Courthouse was dismantled and removed to an offsite location for restoration or replacement and recoating. [CREDIT] Photo © Mike Ullery

Cast-iron cladding that covered the domes and pavilions of the Miami County Courthouse was dismantled and removed to an offsite location for restoration or replacement and recoating. Photos © Mike Ullery

Built in 1888, the Miami County Courthouse was listed on the National Register of Historic Places in 1975.

Built in 1888, the Miami County Courthouse was listed on the National Register of Historic Places in 1975.













The restoration and preservation of historically significant sheet metal and cast-iron façades requires the special skills and expertise of craftsmen and professionals who share an understanding and appreciation of these architectural treasures. These specialists spend countless hours assessing the condition of structural and ornamental metalwork, dismantling components, removing old coatings, and restoring or replacing thousands of individual pieces. Given the exhaustive amount of work and care involved with restoring these national landmarks, specifiers must rely on high-performance coating systems that offer long-term substrate aesthetics and protection against corrosion caused by moisture intrusion, UV light, and thermal cycling.

1 The resource is written by J. Waite, AIA, with an introduction by cast-iron preservationist Margot Gayle. See, Preservation Briefs, “The Maintenance and Repair of Architectural Cast Iron,” 1991, Technical Preservation Services, National Park Service at www.cr.nps.gov/hps/tps/briefs/brief27.htm. (back to top)
2 Important standards include ASTM D4060, Standard Test Method for Abrasion Resistance of Organic Coatings by the Taber Abraser; ASTM D4141, Standard Practice for Conducting Black Box and Solar Concentrating Exposures of Coatings; ASTM D4587, Standard Practice for Fluorescent UV-Condensation Exposures of Coatings; and ASTM B117, Standard Practice for Operating Salt Spray (Fog) Apparatus.  (back to top)
3 For more, visit American Institute of Architects (AIA), San Francisco Chapter’s website at www.aiasf.org/about/history/hallidie-renovation/. (back to top)
4 For more, see Business Wire’s news release, “San Francisco’s Urban Design Community Celebrates Restored Hallidie Building” at www.businesswire.com/news/home/20130501006221/en/San-Francisco%E2%80%99s-Urban-Design-Community-Celebrates-Restored. (back to top)
5 See J.B. Alexander’s, San Francisco: Building the Dream City (Scottwall Associates, 2002). (back to top)
6 This comes from an interview with Lo in April 2013. (back to top)
7 Visit, Durability + Design’s article, “Curtain Wall Project Earns Accolades,” at www.durabilityanddesign.com/news/?fuseaction=view&id=9002. (back to top)
8 Visit www.downtownrising.com/DTR-media/city-creek/downloads/ZCMI_Facade_Fact_Sheet.pdf. (back to top)
9 See Note 1. (back to top)
10 See Salt Lake Magazine’s article, “Restoration 2.0,” by J. Pugh. Visit www.saltlakemagazine.com/blog/2012/01/12/restoration-20/. Historical Arts and Casting also has a video, ZCMI A Legacy Cast in Iron. (back to top)
11 For more, see City Creek Reserve’s news release, A Familiar Face Returns to Main Street: ZCMI Façade is Back at www.downtownrising.com/DTR-media/city-creek/downloads/ZCMI_Facade_Release.pdf. (back to top)
12 This is from an interview with R. Baird in April 2013. An interview was also conducted with M. Call in February 2012. (back to top)
13 For more, see R. Baird and Historical Arts and Casting’s “Restoring Cast Iron Facades (Part 1),” at www.historicalarts.net/restoring-cast-iron-facades-part-1-of-2/. (back to top)
14 This is also from an interview conducted by the author with M. Call in February 2012. (back to top)
15 For more see R. Baird and Historical Arts and Casting’s “The Rebirth of A Cast Iron Gem (Part 1).” (back to top)
16 See Note 15. (back to top)
17 For more see R. Baird and Historical Arts and Casting’s “The Rebirth of A Cast Iron Gem (Part 2). (back to top)
18 This is from an interview conducted with D. Haines in April 2013. (back to top)
19 See Note 17. (back to top)
20 See Note 17. (back to top)
21 See Note 18. (back to top)

Jennifer Gleisberg is an architectural sales coordinator for Tnemec Company Inc., where she provides support for sales and marketing of protective coatings for concrete, steel, concrete masonry unit (CMU), dry wall, and decorative cast iron and sheet metal substrates used on historical landmarks. She is an active member, or has received credentials, from NACE (NACE Coatings Inspector – Level I Certified), The Society of Protective Coatings (SSPC), and the United States Green Building Council (USGBC), where she is a Leadership in Energy and Environmental Design (LEED) Green Associate (GA). With more than 10 years of experience in the coatings industry, Gleisberg brings a customer service perspective to architectural projects that require coating solutions for lasting aesthetics, as well as protection from corrosion, impact and abrasion. She can be contacted at gleisberg@tnemec.com.

To read the sidebars about the project teams, click here.