roofing and roof specialties

Copper from Heaven

Toronto’s Old City Hall receives a new copper roof and replicated ornament.

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By Nicole V. Gagné

The Canadian architect E.J. Lennox (1854-1933) was still developing his plans for the design of Toronto’s new City Hall when he visited the United States in the 1890s. Eager to examine trends in the architecture of municipal buildings, Lennox was greatly impressed by structures in the Richardsonian Romanesque style; in particular, H.H. Richardson’s Allegheny County Courthouse in Pittsburgh, PA. Lennox returned to Canada and in 1899 saw the completion of Toronto’s third City Hall building: a triumph of the monumental Romanesque idiom, which boasted a 300-ft.-tall clock tower modeled on London’s Big Ben but executed with Richardson’s heavy arcading and rusticated brownstone and adorned with a quartet of gargoyles.

Designed by Canadian architect E.J. Lennox and completed in 1899, Toronto’s Old City Hall is a masterpiece of the Richardsonian Romanesque style. The 300-ft.-tall clock tower, modeled after London’s Big Ben, is characterized by four gargoyles at each of its corners. Seen here are the new gargoyles, restored to the tower after removal of the originals 50 years ago. All photos: courtesy of Heather & Little Limited

Although beloved by its public, the new structure began exhibiting problems in a fairly short time. By the end of the 1920s, its clay-tile roofing was removed and replaced with copper in an effort to defray the expenses of sending workmen up to the roof – with its extreme 75-degree pitch – on frequent maintenance inspections of the tile. Less than a decade later, in 1938, a 500-lb. chunk of one of the gargoyles fell off, tearing a hole in the roof and landing in the attic. Soon after that, all four gargoyles were removed in the interest of public safety.

In 1965 a new City Hall was inaugurated in Toronto, and what then came to be known as “Old City Hall” was leased as court space. Developers began proposing to demolish the building, leaving only the clock tower as a fragment of this architectural masterpiece, but a grassroots organization, the Friends of Old City Hall, launched a campaign that saved the building from the wrecker’s ball. In 1989 it was officially designated a Canadian National Historic Site, and two years later The Ventin Group, an Ontario-based architectural firm with offices in Toronto, Simcoe, and Cambridge, began an epic restoration of the building. The dawn of the new century also marked the start of perhaps the most difficult phase of the project – the installation of new copper roofing and the re-creation of missing roof ornament, including the four gargoyles. A competitive tender was put out, and Heather & Little Limited of Markham, ON, was awarded the project.

Expert sheet-metal contractors since the firm’s founding in 1925, Heather & Little was ready to meet the extraordinary challenges of the assignment. Cameron Forbes, vice president, recalls the decision to install a new copper roof. “They had originally used a lighter-gauge copper – something we’ve found in a number of projects – and it was actually a little bit softer in the ‘old days.’ For the new roof, the gauge of the copper was upgraded, which changed the roof’s longevity quite drastically; it may last 25 percent longer than a roof with a lighter gauge.”

Laying a new copper roof for Old City Hall involved the removal of the old roofing, the addition of a new surface of 1/2-in. plywood over the existing wood deck, a layer of peel-and-stick membrane plus insulation spaced with wooden sleepers, and 3/4-in. V-tongue-&-groove plywood covered with Roofshield: a flexible acrylic underlay system popular in Europe but still fairly new in North American applications.

Approximately 66 tons of 20-oz. sheet copper and 20 tons of sheet lead were needed for the 173,600-sq.-ft. roof. The lead figured into the simultaneous restoration of the building’s masonry. “There was also a massive restoration of the masonry during the re-roofing, and a common thing in Europe, which has become commonplace in Canada over the years, is the use of sheet lead to cover the ledges of the masonry, as a protective measure to eliminate natural eroding. Stone copings were covered with lead for the same reasons.”

The concurrent masonry restoration prompted an unusual arrangement between Heather & Little and The Clifford Group of Scarborough, ON, and its subsidiaries, Clifford Masonry Limited and Clifford Restoration Limited. “The project was actually split into two different contracts,” says Forbes. “The clock tower was under contract to Clifford, while Heather & Little handled the whole quadrant of the main building. So on the large project, The Clifford Group was sub-contracted to Heather & Little, and on the clock tower, we were sub-contracted to them. I think that’s the first time in our existence that we worked with such an arrangement on one project, which should give people an idea of its magnitude.”

Working from bosun’s chairs attached to rope falls, crews labored through every season, laying almost four acres of copper sheet in a batten-seam pattern. Before they could start, however, the existing roofing had to be stripped and ½-in. plywood fastened over the existing wood deck. A peel-and-stick membrane plus insulation spaced with wooden sleepers was placed over that, then ¾-in. V-tongue-&-groove plywood was applied and covered with Roofshield (a flexible acrylic underlay system, used regularly for all types of sloped roof systems in Europe and introduced to North American applications about a decade ago). An array of roofline snow guards, dormers, finials and other detailing demanded further precision.

Workers from Heather & Little Limited of Markham, ON, relied on bosun chairs, attached to rope falls, to lay almost four acres of copper sheet in a batten-seam pattern for the new roof of Toronto’s Old City Hall. The roof’s vast size and its complex details – including snow guards, dormers and finials – complicated the painstaking effort. In all, some 66 tons of 20-oz. sheet copper and 20 tons of sheet lead were used to cover the 173,600-sq.-ft. roof.

Along with replacing the vast copper roof, Heather & Little also had to replace a copper turret finial, ridge-hip terminals, and the clock-tower and pavilion finials that had been removed over the years. None of that work, however, equaled the effort of re-creating the missing gargoyles. The original sandstone figures were atypically horizontal and cantilevered out from the clock tower about 9 ft. at each of its corners. The breaking apart that occurred after only four decades was inevitable: The stone’s low tensile strength couldn’t withstand the pull of gravity and the extreme freeze-thaw cycles of such a high and exposed location. Therefore, the decision was made to replicate the gargoyles in metal. The problem was that nobody was sure just what the originals looked like, because no fragments or drawings of them had survived.

“That was one of the biggest roadblocks,” says Forbes, “the fact that there was nothing there that we could see. Everything that remained of the originals had been taken down. There were historic photographs that had been archived, but they were of very poor quality; the resolution was not good, and they were taken from so far away. They gave us a good idea of the size of the gargoyles but not much more. A number of people, including architects and consultants, were involved in the project, and everybody had their own idea of what they should look like. So there was a long stage of modeling and different quarter-scale mock-ups, until finally they decided, ‘Yes, this is what we think they should look like.’”

The design of the clock tower’s original gargoyles was unusual in that the statues were horizontal and cantilevered out from the clock tower about 9 ft. at its corners. Carved in sandstone, the gargoyles weighed enough to begin crumbling dangerously, and so they all had been removed. The replacements were cast in bronze at the end of 2002: an innovation that significantly reduced their weight. An artificial patina solution, mixed with sifted-sand mortar, was applied to give the metal the color and texture of stone.

The Ventin Group approved an appropriate design for the sculptures, derived from gargoyles and grotesques that can be found on Old City Hall as well as other local landmarks, such as Queen’s Park and the Ottawa Peace Tower. Traditional Cut Stone of Mississauga, ON, provided a full-scale version of a gargoyle model, made of shaped foam insulation, which formed the basis of the casting process. “Originally, Heather & Little was contracted to make them in copper,” says Forbes. “But by the time decisions were made as to the final design, we had opted to cast them in bronze; it would have taken too long to have handmade all four of them in copper.”

In December of 2002 the gargoyle components were cast by MST Bronze of Toronto and assembled. Skeletons of stainless-steel armatures were devised for the gargoyles, to anchor them securely to the clock tower. This innovation was necessary because the originals had been cut away from the tower by hand. There were four different stone stumps on the corners of the clock tower, and each gargoyle required a custom-cast base to fit the existing stone profile.

The decision to construct the gargoyles in cast bronze had an additional benefit: a significant reduction in weight over the original two-ton sandstone sculptures. “Including the stainless steel sub-structure, the overall weight was brought down to, I would say, probably about 1,500 lbs. each – maybe even less,” says Forbes. “But I don’t think we actually ever did weigh them.” Naturally, the cast-bronze gargoyles also had to undergo a special patination process to simulate the appearance of sandstone. “They took one of the artificial patina solutions, mixed in a portion of the sifted-sand mortar with it, and then applied it so that the cast bronze actually took on the exact color of the stone,” Forbes adds.

This overhead view of the roof on Old City Hall gives some idea of the building’s epic size and the extremity of its 75-degree pitch. Developers proposed to raze the building after a new City Hall was inaugurated in Toronto in 1965, but the building was rescued by the efforts of a grassroots organization, the Friends of Old City Hall, and in 1989 it was officially designated a Canadian National Historic Site. Two years later, restoration work on the building began. Work on the roof alone took five years to complete.

Artificially accelerating the patination of the roof was out of the question. “At Heather & Little, we receive numerous requests to artificially patina various exterior copper components, but in our experience the best protective process is by natural patina – just let it happen the way nature intended it to be,” says Forbes. “In my opinion, this protects the copper for a longer period of time. Some people do find the discoloration unpleasing to the eye, but others see it as striking and beautiful as it ages. Of course, I’m kind of biased, as I think this is the way copper is meant to age.”

A team of over 30 sheet-metal workers, carpenters and roofing tradespeople labored over the roof of Toronto’s Old City Hall for five years, and during this time, the building and its courts were in continuous use. “The whole project was done without any disruption of the ongoing business at hand in the courthouse,” says Forbes. Not surprisingly, this spectacular effort was awarded Project of the Year for Across Canada from the Canadian Roofing Contractors Association in 2006. But the greatest award for the artisans of Heather & Little is the spectacular sight of one of Toronto’s most beloved and beautiful old buildings enjoying a new and longer-lasting life, with its original glory not just restored but enhanced as well.