Rescuing the Dome

Posted on 03 August 2012

A temporary steel band that encircles the outer dome at the John Jermain Memorial Library was installed on Monday, July 30th, 2012, that will hold the dome in place securely while a new, permanant band is installed

by Amanda Wyatt

What do Grand Central Station, the Boston Public Library, the Cathedral of St. John the Divine and the University of Virginia all have in common with John Jermain Memorial Library?

Each of these historic structures feature domes designed by the R. Guastavino Company, a celebrated architectural firm of the late 19th and early 20th centuries.  The company, which used a special type of arch technology and terracotta tiles, built over a thousand domes across the globe.

But today, the dome at John Jermain — which is often considered the “crown jewel” of the building — is undergoing major repairs.

In the midst of their multi-million dollar renovation project, workers at Trunzo Builders recently discovered that the brass tension ring inside the dome had been significantly corroded.

In an interview, JJML library director Catherine Creedon said that most of the corrosion was caused by over a century of water damage.

“I think I’m learning that whatever it is in life, water’s our enemy,” joked Creedon. “Water sort of sustains us, but in terms of its effect on inanimate objects, it really hastens their aging process.”

“We had a hundred years of heavy winds and nor’easters being driven against the building,” she added. “It’s an organic building, it’s a breathable building, and it’s made out of natural materials, so it’s not exceptional that we would find corrosion or water damage in the dome.”

Creedon explained that the dome is made up of two layers – the copper layer that can be seen from the outside, and the inner layer made of terracotta tile. The terracotta dome is self-supporting, using Guastavino’s innovative arch technology.

“But the drum, the straight-sided cylinder that fits below the dome, was held in place by an iron compression ring,” said Creedon. “Once we took off the copper [layer], we realized that that compression ring had corroded.”

For both safety and architectural reasons, Trunzo Builders — the company renovating the library — is in the process of replacing the ring.

“To do that, we have to set up a temporary buttressing of the whole dome,” said Pat Trunzo, the company’s owner and CEO. “Basically, it looks like a lot of spokes that we’re going to put back against the base of the dome from a new temporary tension ring.”

Once they receive the temporary ring, the builders will assemble it on top of the posts that they have erected.

“Then we’ll start blocking from the inside of the temporary ring back against the masonry that is at the base of the dome structure,” Trunzo said.

After an engineer examines the work, Trunzo said his company plans to complete an eight-foot section of the dome at a time.

“We’re going to take out our spoke blocking to move the masonry, cut out a piece of steel ring, put a new stainless steel piece of ring in, ground it and move to the next section adjacent to it, and work our way around the whole dome,” Trunzo said.

Trunzo noted that the company had also begun installing a sophisticated geotechnical monitoring system on the dome that would detect any movement. If there’s even a slight movement, work on the dome will immediately cease and the situation will be reviewed by an engineer.

Once the monitoring system is set up and “the engineer has signed off on the setup, then we’ll start removing masonry, cutting out the old steel ring, replacing the new steel ring, grouting it, and so forth,” Trunzo said. “But we figure it will take a week’s time to get all the way around the dome.”

Regarding the rest of the dome, Trunzo believed that the tile work was still strong. However, some of the mortar-work between the tiles was soft, which is something he said they plan to look into after the tension ring has been replaced.

Creedon said that she was pleased that they had discovered the problem with the ring “at a time when the building was still agreeable to that repair.”

“Visually, if nothing else, the dome links us to all of these other historic institutional buildings across the Northeast,” she said. “So in that sense it ties us into a fabric that spans from Boston to Virginia.

“It also, I think, is the first welcome that anyone coming into Sag Harbor from the south sees,” she added. “It really is a beacon about this village’s commitment to the arts.”

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One Response to “Rescuing the Dome”

  1. Miata says:

    The dome is the centerpiece of the building, both inside and out. Sounds like complex repairs.


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