Last year, early in the morning on January 15, an express mail delivery truck accidentally took down one of Seattle's most iconic landmarks, the Pioneer Square pergola. This month, the Seattle Parks Department, with the aid of Seidelhuber Iron and Bronze Works, will begin the reinstallation of the restored monument that originally marked the location of public toilets for the 1909 Alaskan Yukon Pacific Exposition.

A lot was written about the significance of the pergola immediately after the incident. Few people (except maybe those who enjoyed a little unobstructed green grass on its triangular site) debated the restoration question - the structure is undeniably important, and no public subsidy was required for the rebuild. For many residents and businesses of Pioneer Square, the off-site restoration effort was a persistent glimmer of hope regardless of what else was going in the neighborhood.

Newspaper articles have focused on the human-interest element of Seidelhuber's efforts to restore the landmark, and rarely described the technical components of the story. The circumstances of its accidental demolition have, in fact, significantly contributed to its preservation. Because of the accident, the pergola is in much better shape than it was before, and is much more likely to remain standing as long as people continue to appreciate it as a significant part of our city's heritage.

Higher Standards

In a Seattle Times article printed the day after the pergola collapsed, then-mayor Paul Schell chided, "I hope this guy's got good insurance." Yes, indeed, this was critical to the restoration story.

The National Park Service's standards for the rehabilitation of historic structures are based upon practical reality. They allow for cost savings when lower rehabilitation costs may mean the difference between an economically feasible rehabilitation and an infeasible project that may deter developers from doing the right thing. Preservation incentive programs, such as federal tax credits and local preservation commissions, like the Pioneer Square Preservation Board, use the Park Service's standards as a basis by which to measure the quality of historic building rehabilitations.

These standards stipulate that if reuse and restoration of original materials is not reasonable, the materials may be replaced with the same material. If this is not reasonable, the original material may be replaced by a similar material. According to Heidi Seidelhuber, she understood that her task was to restore rather than replace. She thinks replacement would have been more expensive than restoration, but that it was fortunate that funding did not dictate an acceptable shortcut. Thankfully, because funding came from the insurance company, not public subsidies, or a private developer seeking a preservation solution that "pencils out," almost all of the restored pergola is original.

Cast Iron Age

Cast iron technology came into vogue in the mid-19th century, and was the perfect consummation of the Victorian taste for elaborate ornamentation and the mass production techniques growing from the Industrial Revolution. The process made it possible to mass-produce extremely ornate architectural details - details which looked to stone and woodcarvings as source material. In many East Coast cities, such as New York, Charleston, and New Orleans, cast iron was popular as an internal framing material, and as a material used for prefabricated façade components. London's Crystal Palace, built for that city's 1851 World's Fair, was comprised of prefabricated cast iron elements and glass, and is now known as one of the benchmarks of nineteenth century architecture. The Eiffel Tower (1889) is another lasting example of cast iron exposition design.

Seattle's pergola falls into this family of exposition structures, even though it wasn't built on the Alaskan Yukon Pacific Exposition grounds located on what is now the University of Washington campus. The pergola marked the spot of newly constructed public toilets, put in place in time for the arrival of throngs of exposition visitors. Cities preparing for large, tourist driven events, such as world's fairs, often spruce up public amenities like lampposts, railings, water fountains, and public restrooms.

The Process

Cast iron technology uses woodcarvings as the basis for casting molds. As a result, cast iron work resembles woodcarving and is difficult to reproduce in other materials. A good reproduction would therefore be a casting made in a sand mold formed from a similar woodcarving. Ballard Brass is able to do such work. In the past, Seidelhuber has worked with this company and states that "their reproductions are indistinguishable from the original, but it's still not the same as having the original materials and handiwork repaired."

If the pergola had been restored with a minimal budget, the final product might have lost quite a bit in translation.

Waterproofing

When the pergola was first put in place, the components were painted where they faced out, but not inside the hollow structure. Over time, through common wear, freezing and thawing, hairline cracks formed in the historic welds. Water slowly seeped into these tiny entry points, and rusted through the cast iron from inside out.

Seidelhuber treated both the exterior and interior elements with a marine paint system. If water gets inside the hollow structure in the future, the structure will be protected. Seidelhuber installed drain holes that help prevent the accumulation of water inside the structure. The paint system is designed to prevent water from entering the cracks and flaws in the cast iron elements. Once water enters these flaws, the regular freeze and thaw action would speed deterioration and breakage.

Seidelhuber calls further attention to the ideal circumstances of the accident. If the pergola had fallen on concrete, restoration would be much more difficult, and perhaps even impossible. Thankfully the structure fell on a soft garden.

Reinforcements

Seidelhuber has been told that before its collapse, the pergola was not very well attached to the ground. According to Seidelhuber, this is often the case with historic structures like the pergola built during a time when fire was a more popular public safety concern than earthquakes. The pergola fell because it was hit from the side, and twisted off of its base.

The pergola's construction - with hollow cavities - allowed for an invisible internal reinforcement system inside the original wrought iron structure. This internal skeleton will be attached to a base plate that will help the pergola withstand earthquakes or future crashes.

Generosity's Limit

Although the insurance company paid for many costly restoration solutions, the firm piped up when the issue of welding versus other bonding methods came to the table. Welding involves using different alloys that do not produce a perfect, seamless fix. The ideal solution, offered by Cast Iron Repair, a shop based in Everett, is heating the original cast iron elements until red-hot, and then pouring in material that would fuse and intermingle with the historic alloy. The result would be perfect, but the costs enormous, and the process would have delayed the reinstallation of the landmark substantially. The compromise was the aforementioned marine paint system, which provides needed waterproofing at a substantially lower cost.

Long Term Solution

According to Seidelhuber, the accident that demolished the pergola made its preservation easier. "It's much harder to repair something on site," she noted, "it makes the job much more complicated." The unintentionally dismantled structure has received an extremely thorough restoration, and will be reinstalled with every intention that it will last a very long time. "If the pergola lives another 100 years," Seidelhuber reflects, "it will be because it went down now."

Here's to happy accidents.

To stay updated on the Pergola's progress, visit the City of Seattle's Pergola website.

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