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Re-Roofing / Retrofit roof applications are essential
for commercial builders.
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Recover
roof application for single-ply membrane, ballasted roof
assembly. |
Roofing recovery is a process used on many commercial building
re-roofs. In this process the existing roofing membrane is left
is place. Any large pieces of debris are removed, a recover
board is typically mechanically attached to the structural deck
and a new roofing membrane is installed on top of the recover
board.
This process has many benefits. From an environmental standpoint,
leaving the existing membrane in place reduces the amount
of waste material sent to the landfill. It also can increase
the energy efficiency of the building by leaving existing
insulation in place while adding additional insulation. For
the building occupants, it reduces the disruption to normal
building operations since no tear-off is required.
One concern with this process is that the existing roofing
system most likely contains some amount of moisture, since
the roof is not normally replaced unless there have been
a history of roof leaks.
Extruded polystyrene foam (XPS) makes an ideal roofing recovery
product. The manufacturers of XPS offer a wide variety of
products for use in this application, including fan-fold
products specifically designed for quick installation. The
fanfold products have a variety of facers designed to work
with specific membrane types. They also offer board-stock
products designed for use under all single-ply roofing membrane
systems.
—Case Studies—
Akron Civic Theatre, Akron,
OH
The Akron Civic Theatre in Akron, Ohio, was designed
by John Eberson and built in 1929 at a cost of $2,000,000. It stands
as a historic reminder of the elegant Loew’s theater chain
and is one of only five remaining “atmospheric theatres”
in the United States. It is listed in the National Historic Register.
Once a plush entertainment center, the 2700-seat theatre offered
films and vaudeville acts in the 1930’s bringing thousands
of people to downtown Akron. Following World War II into the fifties,
the Civic suffered a period of minimal use and fell into a steady
pattern of deterioration. By the mid-1960’s the wreckers ball
was poised to swing. In 1965 the first effort to save the Civic
was undertaken, and from this initial aid a series of fund raisings
and restorations has taken place culminating in 1987 in a community-wide
capital restoration and endowment campaign of $2.8 million. The
theatre’s final restoration is now underway and upon completion
this marvelous public hall with its rococo décor is sure
to recapture the splendor of its earlier days and, at the same time,
spark redevelopment plans for downtown Akron over the next several
years. Happily, UCI (now Owens Corning's Specialty Foam Division)
was able to play a rather significant role in this restoration project.
One of the first steps taken in the final restoration of the Civic
was the replacement of the roof to preserve prior and ongoing restoration
work. The reroofing project involved six separate areas totaling
28,000 square feet: outer lobby, grand lobby, auditorium, stage
house, offices and south annex. Neither insulation nor weather resistive
toppings such as gravel had been used on the original roof. In preparing
the old roof, covering materials were completely removed down to
the gypsum plank deck in order to reduce weight, remove accumulated
moisture, and ensure the quality of the gypsum deck which was to
remain in place.
The architect for the project, Rasmussen Design Group of Akron,
Ohio chose a single ply roofing assembly consisting of the existing
3” gypsum deck, 1½” thick, 2’ by 8’
XPS TYPE IV as listed in ASTM C 578 2002 extruded polystyrene insulation,
½” wood fiber board mechanically attached to the gypsum
deck with 4” fasteners (allowing for a minimum 2” penetration
into the deck), and 2 ¾” square galvanized steel washers.
The fasteners used had large threads to distribute wind uplift loads
over an area compatible with the strength of the deck. An EPDM single
ply membrane was adhered to the ½” wood fiber substrate.
While XPS TYPE IV as listed in ASTM C 578 2002 was included in the
new roof to help reduce high heating bills for the old theatre,
the thickness was limited by the length of fasteners used to attach
the single ply system substrate to the gypsum deck. “XPS insulation
was chosen because of its strength and high R-value of 5 per inch
of thickness,” said Joe Herdna of Branch Roofing, Akron, roofing
contractor for the project. Also considered was XPS’s ease
of installation and long term insulating performance.
The entire roof replacement was completed in May 1988. The Akron
Civic Theatre is now delighting its patrons once again.
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