|
Commercial roof system maintenance is challenging, and involves
careful attention to details, safety
issues, and determining the best materials
and installation methods. However,
imagine adding another unique challenge
to such a project — performing
all work during the night.
Madsen Roof Company
of Sacramento, CA, faced that challenge
when it performed roof system repairs
and coating installation on the headquarters
building of the California Lottery
Commission in Sacramento.
The reinforced PVC
membrane roof system on the California
Lottery Commission headquarters building
had shown signs of deterioration,
including many cracks and crazes.
In fact, the roof had more than 250
documented leaks.
The roof needed a
durable coating that could protect it
from further weathering, provide essential
adhesion to a PVC system and resist plasticizer
migration. The facility manager chose
a National Coatings Corp. AcryPly roof
maintenance coating and hired DC Consulting
Services, Sacramento, a roof consulting
firm.
DC Consulting Services
inspected the roof and initially believed
it could not be repaired. And 168
heating, ventilating and air conditioning
(HVAC) units complicated the possible
roof replacement options because any
fumes resulting from the work would
be drawn into the building. Therefore,
work would need to be done when the
building was unoccupied.
However, after DC Consulting
Services researched the situation
further, it determined a re-cover
and tear-off were not necessary, and
the roof could be repaired. "The solution
came from National Coatings Corp.
because the AcryPly roof maintenance
system marries well to PVC membranes
and performs like a new roof system,"
says Peter Madsen, president of Madsen
Roof. "This feature eliminated
the need for tear-off, and the acrylic
products had little odor. The project
still was required to be performed
at night during unoccupied hours as
an additional safety measure to further
reduce any effect on occupants."
 |
Power
washing with hot water
to remove algae
from the existing PVC
roof |
|
Madsen Roof has
experience using coatings for roof
system maintenance and was chosen
to perform the specified AcryPly roof
system repairs. The original roof
assembly consisted of a plywood panelized
deck with 1/4-inch- (6-mm-) thick
DensDeck and a 45-mil- (0.045-inch-
[1-mm-]) thick mechanically fastened
PVC single-ply membrane.
The HVAC units were
a significant reason for performing
the nocturnal work when the building
was unoccupied. The new reinforced
coating system in the process of being
applied over the old PVC membrane
"HVAC units draw in significant
outside air from the perimeter of
the units," Madsen says.
"The spray
application of acrylic coatings would
generate odor close to the HVAC units.
When the coatings were installed at
night, the units were turned off and
covered in plastic then uncovered
for day use. This was done repeatedly
as each coating application was installed."
Although easier for
the building's occupants, working on
the roof at night was not without its
challenges for the crew.
"The largest
percentage of work was done at night,
and the challenge was adjusting to the
swing shift and providing independent
power and lighting," Madsen says. "Madsen
Roof established a consistent work schedule
so workers could adapt to the new work
hours. Because there was little 'shop'
support from our company at night, we
provided backup equipment to prevent
downtime. We also had to alternate scopes
of work in case we could not spray because
of wind. And good visibility was essential
for safety and quality control; this
required multiple directions of lighting
for the detail work on the 168 HVAC units.
"In addition,
the HVAC units are supplied by electrical
conduits running across the roof,"
he continues. "The conduits carry
440 volts and had to be lifted while
crews worked below."
 |
The
new reinforced coating
system in the process
of being applied over
the old PVC membrane |
|
Working under spotlights,
often until dawn, required staging
the work areas and relocating all
the lighting equipment as work areas
were completed. The crew power washed
the single-ply membrane with water
at 105 F (41 C) to remove all contaminates.
Madsen Roof applied National Coatings
PVC primer and a base coat of A600
quick-set adhesive. The crew broomed
a layer of polyester into the quick-set
adhesive and applied another topcoat
of A600. Two more topcoats of A600
were applied to increase thickness.
Flashing around penetrations
and over parapet walls went smoothly,
creating a watertight, monolithic, ultraviolet-protective
membrane over the existing roof. For
additional protection, walk treads were
installed around HVAC units.
Other obstacles
Various safety precautions were taken
during the project, especially because
the work was being performed nocturnally
with limited lighting from halogen
light towers. The company used tied-off
ladders, twist-lock extension cords,
flood lights, insulated gloves for
handling electrical conduit, fire
extinguishers, safety lines and barricades
in areas with gutters or low parapet
walls.
"We also always
had a backup plan for additional power,"
Madsen says. "Some power was
available on the building, but we
kept two generators on-site at all
times."
The nighttime coating
installation presented a challenge with
regard to moisture, creating issues with
material cure times.
 |
The
topcoat process and HVAC
protection |
|
Heavy dew that
settled on the roof at night slowed
the coating's drying rate and threatened
to wash it off the roof. AcryShield
A600 was used to remedy this issue,
allowing the coating to resist dew
even when the coating was wet.
Another challenge
was installing a sprayed-in-place nonskid
walkway system that originated at each
roof hatch and led to all HVAC units
and heir perimeters.
"There were four
roof hatches, and the walkway system
consisted of 7,000 lineal feet (2,129
m)," Madsen says. "The pathway
was 'taped-out' and primed, and then
a base coat with ceramic granules
broadcasted into wet coating was applied.
Another topcoat was applied, and the
taping was removed at just the right
time to prevent the coating from adhering
it to the finished roof system."
"Sacramento
is cooled in the summer evenings by
the Delta Breeze, a prevailing east
wind that begins around 7 p.m.,"
Madsen says. "Preventing overspray
to equipment, cars and canopies was
a real concern and required significant
planning to shield spray. We had to
stop operations when wind gusts were
above 15 mph (7 m/sec)."
The company predominately
worked at night under spotlights but
eventually discovered the coating's low
odor allowed workers to work during the
day without any concerns about fumes
being drawn into the HVAC intakes.
"About 10 percent
of the work was completed on Saturdays
when the building was not occupied,"
Madsen says. "The HVAC units
were on during the beginning of the
walkway application and the building
was checked for odor at this time
with no odor detected. We began increasing
the application during occupation
of the building with no adverse effects."
Applying a spray-applied
product at night made this project
unique. The crew worked more than
20 hours per day to meet the production
schedule. In addition to the night
crew, a separate crew worked during
the day to power wash and prep the
roof. This allowed the night crew
to focus solely on the installation
of the reinforced coating system.
Madsen says the result
was more than satisfactory.
"The National
Coatings AcryPly system is fully compatible
with the existing PVC membrane, and this
proven, reliable system will last for
15 years with periodic inspections."
"The finished
product met and exceeded the expectations
of National Coatings, the roof consultant
and owner," he continues. "And
the satisfaction of eliminating hundreds
of leaks was particularly rewarding."
Krista Reisdorf is
managing editor of Professional Roofing
magazine.
Project name: California Lottery Commission,
Project location: Sacramento, Calif.,
Project duration: August 2005-October
2005 Roof system type: PVC membrane roof
system with acrylic polyester-reinforced
coating system Roofing contractor: Madsen
Roof Co. Inc., Sacramento Roofing manufacturer:
National Coatings Corp., Camarillo, Calif.
Roof consultant: DC Consulting Services,
Sacramento © Copyright 2007 National
Roofing Contractors Association |
