Renovating a Historic Cathedral
RHEINZINK protects and preserves heritage of
Built in 1894, Christ Church Cathedral was the first church in
Vancouver, British Columbia, Canada. Over the
past 22 years, the church underwent a major four-phase
renovation, which concluded with the total replacement of its roof.
The church's original roof was cedar shake, and over the years,
various additions and modifications were undertaken, but none
contributed significantly to the historic structure's long-term
In 1995, a formal master plan was undertaken to make
the cathedral structurally sound and to meet seismic stabilization
requirements. As part of the multiphase plan, the church underwent
aesthetic and acoustical upgrades, in addition to basic functional
improvements. "The purpose of the most recent and final phase of
the restoration was to replace the roof for critical weather
protection, thermal and acoustic upgrades, while completing the
seismic diaphragm, accepting the parameters of working on a
designated Heritage building and the need to work closely with the
City of Vancouver Heritage Planners under the purview of the
Vancouver Heritage Commission," says Ron Clay, MRAIC, associate at
Vancouver-based Proscenium Architecture & Interiors.
The project's final stage of replacing the roof
became a modern marvel in Vancouver, as the entire building was
completely enclosed in a massive scaffold with a giant tarpaulin
covering. This was to protect the church from weather as the
existing roof was removed. To allow use for a traveling gantry
crane, which moved materials to all areas of the roof, the
scaffolding reached 100 feet high.
Workers had to be in full HazMat gear to remove the
existing roof, since the artificial slate material was bonded with
asbestos. Additionally, the felt layers contained asbestos and the
plywood layers underneath were contaminated by lead dust.
Before the new zinc roof could be installed by
Vancouver-based TEK Roofing, it was necessary to get a level
and true substrate, as the structure had settled and shifted
considerably in the years since it was originally built.
Additionally, construction methods were different a century ago.
"We were surprised at how bad the structure was when we opened the
building up," says Ian Birtwell, a parishioner and volunteer
project manager who functioned as liaison with the church. "The
connections to walls were very poor-basically gravity connections.
That's the way they built in those days. And the roof ridgeline
dipped 6 inches. We used a laser system to create a computerized
3-D model that revealed the high spots and low spots so that we
could get a totally flat roof."
Clay notes that much consideration, review and debate
went into the retrofit roof construction assembly, to produce a
system that was both economical and effective at achieving the
current ideals for envelope, thermal and acoustic performance.
Pacific Building Envelope Maintenance Ltd.
(PBEM), Delta, British Columbia, also helped in leveling the
structure. "PBEM did a lot of the framing working under the
supervision of our superintendent," says Terry Kellogg, president,
TEK Roofing. "PBEM was very instrumental in getting us a level
roof. It was a tough, tough job. They added a huge amount of
structural steel. We couldn't have done it without them."
Durable and Maintenance Free
Woburn, Mass.-based RHEINZINK America
Inc. supplied approximately 12,000 square feet of its prePATINA
blue-gray RHEINZINK material for the roof, which was installed in a
traditional batten seam profile.
Hugh Cochlin, Architect AIBC, AAA, MRAIC, LEED AP,
principal at Proscenium, says good Heritage practice requires the
renovation be respectful of original materials. "Slate was
initially suggested by several interested parties but its weight
was problematic for the seismic upgrade," he explains. "We
gravitated to zinc pretty early in the process. We wanted a durable
material that would last forever. We expect to get 100 years or
more from the RHEINZINK. Plus it looks contemporary but is
respectful of good Heritage practice. The Heritage Commission
quickly approved our use of it."
RHEINZINK's traditional prePATINA blue-grey color was
another reason for selecting the zinc, along with its ability to
repel moss. "Zinc was a natural choice for a Heritage cathedral as
its appearance will patina over time to register the prevailing
conditions," Clay says.
"Everyone likes the way the blue-grey RHEINZINK
complements the natural stone on the building," Cochlin adds.
Cochlin says all details were drawn by hand. "That's
definitely old school, but particularly appropriate for a Heritage
project. We worked closely with TEK Roofing and had many on-site
meetings. There was definitely more collaboration with the
installer than is the norm today."
"Due consideration was given to each integral
component of the refurbishment/reconstruction details, which is
clearly and concisely represented in the hand drawings," Clay adds.
"Of primary concern to the design team was the subtleties,
accuracy, consistency and integrity of the hand drawings could
have been compromised if translated to CAD."
"The RHEINZINK panels are literally all hand formed,"
Kellogg says, adding that he's an old-school guy and everything the
company does is traditional. "No machines were involved other than
our breaks. The traditional method is just more exact in terms of
the details because you are fabricating every single piece."
The detailing was complex with multiple interfacing,
and complicated transitions. "There was no caulking, no screws-all
traditional methods," Kellogg says. "There were lots of pitch
changes and elevation changes that made the installation
timeintensive. It was definitely a labor of love."
Additionally, the drainage system used the
traditional 6-inch RHEINZINK half-round gutters with RHEINZINK
hangers, outlets and expansion joints. Five-inch gutters were used
on several small dormers. "It's a beautiful system and complements
the scale of the roof," Kellogg adds.
To complete the project, TEK crew ranged from 10 to
20 individuals, depending on what needed to be done. Kellogg worked
alongside his crew for much of the job, spending nearly two months
on the tools. "It was quite enjoyable," he says.
Christ Church Cathedral, Vancouver, British
contractor: Scott Construction Group, Burnaby,
British Columbia, Canada, www.scottconstructiongroup.com
Architecture & Interiors, Vancouver, www.proscenium.ca
Framing/building envelope maintenance: Pacific Building Envelope Maintenance Ltd.
(PBEM), Delta, British Columbia, www.pbemltd.com
Metals, Burnaby, www.alesthermetal.com
Roofing, Vancouver, www.tekroofing.ca
Metal roof panels/gutters: RHEINZINK America Inc., Woburn, Mass., www.rheinzink.us