While the damage to the Cathedral caused by the August 2011 earthquake is disheartening, a new generation of Cathedral-philes has seen the restoration process open unexpected access to areas and artistry not explored in decades. From the apse buttresses built in the early years of the twentieth century to clerestory vaulting near the west rose window completed around our nation’s bicentennial, the Cathedral is sharing its secrets and its steadfastness to teams of experts charged with restoring the building’s glory and ensuring its place for the centuries to come.

Ceiling Sealing

The Gothic architecture that lifts every visitor’s eyes toward heaven and speaks the transcendence of God to pilgrims also creates vast expanses of masonry and stained glass with no access short of custom scaffolding. In August scaffolding arose in multiple locations within the Cathedral, joining exterior scaffolding that is both stabilizing damaged stonework and offering access to masons and engineers to address the first of six buttresses that support the curved east end of the Cathedral known as the apse. The interior scaffolding in the north and west balconies provides a “dance floor” for rolling scaffolding that reaches each stone in the severies—the stone infill between the vaulting ribs—and the stained glass windows at the clerestory level. A third dance floor has been built on lightweight aluminum (Haki) trusses that span the two western most bays of the nave from north clerestory to south clerestory to afford similar access to the 300-odd–foot length of the nave ceiling without building nearly 100 feet of scaffolding from the nave floor. The plan is to inspect, assess, clean, and repair bay by bay, hop-skipping the Haki trusses down the nave to the great crossing and into the transepts and great choir over the next year and a half.

Since August 2013, separate companies have examined the two balcony ceilings. Wiss, Janney, Elstner Associates, Inc., (WJE) has visually inspected and physically sounded the west balcony and the two westernmost bays of the nave, which are constructed of traditional limestone masonry. WJE had previously performed the post-earthquake inspection of the outer nave aisles and had provided the difficult access team that rappelled down the west façade of the building and the central tower to inspect for damage. Building Construction Associates, Inc., (BCA) has examined the ceiling of the north balcony, which consists of a lightweight, porous cast-stone acoustic liner called Akoustolith. Akoustolith was developed and patented in 1916 by the R. Guastavino Company to enhance intelligibility of the spoken word in the era before sound systems. BCA has performed similar assessment work at St. John the Divine in New York City and is an authority on dealing with Akoustolith.

Unfortunately, the tile has been recognized to be detrimental to acoustics for music and particularly for reverberation for pipe organs. The Akoustolith tile behaved very differently from the limestone during the earthquake, resulting in cracking and delamination of the tiles from the terra cotta substrate. The accessibility afforded by the scaffolding permits not only earthquake- -related repairs to the tile, but also sealing of the Akoustolith to improve acoustics. The tile was installed at the ceilings of the north transept, the crossing, and the first three bays of both side aisles in the nave and in several areas of the triforium. Acousticians from Kirkegaard Associates have just finished testing sound absorption of potential treatments in a test area at the northeast triforium. After providing a full scale mockup of the treatment at the ceiling of the north transept, the Cathedral Chapter has approved proceeding with this work—in hand with other work outlined by the inspections—as long as funding is available.

Overlooked, Overhead

The masonry inspections have found very few surprises and, in fact, have revealed only minor damage from the earthquake. Nevertheless, there is some chipping of limestone and loosened or lost mortar. The inspections have also revealed “deferred maintenance” needs, including addressing joints that have opened or shifted since construction and upgrading caulking, not to mention removing stains left from long since–repaired roof leaks.

Although the masons briefly addressed issues in one corner of the west balcony in the mid-1990s, most of the stone and glass haven’t been viewed up-close since the 1970s. “These windows are filthy!” exclaims mason foreman Joe Alonso. “They’ve never been cleaned, and your hands get dirty just touching them.” Cleaning the windows is just one aspect that stained glass expert Andrew Goldkuhle is considering. A variety of sealants and mortars attempt to keep the windows water tight, and each has fared differently over the years as age and the environment have taken their toll. In some locations metal rods that secure the windows have stressed mortar to the point of cracking, the lead caming between the individual pieces of glass has flexed in the summer heat and the winter cold, and imperfections in manufacture have become apparent. Goldkuhle is evaluating whether these issues require attention and is outlining an appropriate set of measures to implement on the nave clerestory windows, as well as the three rose windows.

WJE has provided the Cathedral with two sets of recommendation documents from an engineering perspective. One document outlines inspections and repairs to be performed as the scaffold marches from west to east down the interior nave. A second report outlines requirements for restoring the apse buttresses, including pinning slipped and dislocated stones and methods for rebuilding their pinnacles using earthquake-resistant methods. “Our hope is to repair the building elements that were impacted by the earthquake in such a way that is not overly invasive but that improves how they might perform if there were to be another seismic event, God forbid,” says Jim Shepherd, director of preservation and facilities.

As for the north balcony, besides the acoustic recommendations for the Akoustolith, BCA has recommended cleaning the tile and repairing all observed deficiencies that were either a result of the earthquake or age. Reflects Shepherd, “Fortunately there are only a few conditions with the tile that require repair—failed mortar joints, loose or vibrating tiles, and aging edge sealant. The most challenging of these is the repair of the loose tiles, which requires injecting grout to fill the voids behind the tiles.” All these reports are being used as the basis both for the standard of work to be performed and as bidding documents for proposals for the actual work. The Cathedral anticipates to complete bidding in the coming weeks, with contractors beginning work in late winter.

The Exterior

Cathedral masons Andy Uhl and Sean Callahan have been about a similar task on the apse buttresses. The two now-famous stonecarvers have been replacing mortar, installing “Dutchman” repairs where patching the stone is possible, and re-carving details in new stone to replicate the original artisan’s work. Their work will provide a standard for the restoration of the remaining buttresses, which will be done by the selected contractors. “Joe [Alonso], Andy, and Sean had a full load of work before the earthquake, and while we want their work to be the standard, we need outside help to complete it,” says Canon Andrew Hullinger, senior director of finance and administration. Uhl and Callahan have discovered many techniques—not all of them useful—employed by the original builders. As they’ve addressed earthquake damage, they have also upgraded structural reinforcements, replaced missing mortar, and replaced spalled stones. Still ahead of them is filling in the nearly inch-wide gap where a stone slipped down as the buttress expanded and contracted in the earthquake. Using stone and mortar, they will fill the gap and reshape the underside for appearance, while implementing WJE recommendations to ensure engineering stability.

Stained Glass

Andrew Goldkuhle, whose father Dieter fabricated many Cathedral windows—including the “Creation” west rose—has not only offered inspection of and recommendations for the clerestory windows, he has also just completed work on a pair of panels from the south Te Deum window. The two Te Deum windows, flanking the high altar, are the Cathedral’s tallest windows, reaching from just above the reredos to the top of the apse walls. The windows have long been a source of leaks during storms, and Alonso had, in fact, created temporary interior plastic deflectors to keep rain water from showering down on the high altar. Goldkuhle has now removed two panels—easily reached with the earthquake scaffold in place—and disassembled, cleaned, and reassembled the glass pieces with new caming and additional integrated support to ensure longevity. The restored panels are visibly cleaner and brighter, and flaws (whether from fabrication or age) have been minimized to enhance watertightness. “Now,” says Shepherd, “we can proceed to remove the remaining stained glass panels from the Te Deum windows when the interior ceiling restoration scaffolding reaches the east end. Much of the cost of restoring the stained glass is access. We can benefit from a dual purpose for the interior scaffolding to reduce costs.”

Any architectural work—whether maintenance, earthquake repair, or upgrading—depends on accurate, as-built drawings. As an integral, early component to all these projects, Shepherd sought out Direct Dimensions, Inc., (DDI) to perform a high-resolution infrared scan of the Cathedral, inside and out, in order to generate a complete set of electronic architectural drawings usable for all these and additional work—and to have a record of the Cathedral in event of any future damage. “This scanning work is amazing! DDI has provided more than 860 scans of the building and fabric. They did a little showing off as well by providing a couple of 3D printer mini-replicas of some of our fine arts treasures based on their scans. And the drawings themselves are absolutely essential to restoring and maintaining this historic landmark—for the first time in the history of the Cathedral we have extremely accurate, electronic, as-built drawings!” says Shepherd.

In addition to these rather visible projects, Shepherd is also working on a variety of other, more hidden tasks, ranging from life-safety initiatives and energy efficiency to deferred and ongoing maintenance of all the Cathedral’s infrastructure. Heating and cooling systems, lighting and dimmers, and plumbing and electrical systems all require attention, especially in a building that just celebrated its 107th birthday. “Although the earthquake work is the most visible restoration focus, there are many non-glamorous building components, such as our rooftop chillers, which also require attention in order for us to be good stewards of this historic structure for future generations,” says Shepherd. And it’s all vital. As a spiritual home for our nation, the Cathedral is a constant symbol and witness for faith in America, and this national treasure is surely a legacy for future Americans yet unborn.