The SFPUC was presented with two available options:
1.Tear off the current roof and install a new one.
2.Overlay the existing roof with a new membrane.
The SFPUC opted to re-cover the existing roof as replacing the old roof would take longer and interfere with the symphony’s rehearsal and performance schedule.
Dregger recommended a white 60-mil-thick thermoplastic PVC roof system.
The Congdon Roofing crew had less rooftop field seaming to complete, thus making the roof easier and quicker to install with fewer hours of labor.
The warranty on the custom-fabricated membrane roofing system does not exclude ponding water or consequential damages.
The system is clean and uses no hazardous materials, which was important to church officials who did not want any messy tar kettles on the roofs or near the buildings that were occupied during the installation.
Reduced waste during the manufacturing and installation process.
roofing systems considered
membrane sheets are thoroughly inspected before leaving the manufacturing facility. All of the seams are inspected by a designated inspector; sheets are trimmed and measured prior to being packaged for delivery to the job site.
The Louise M. Davies Symphony Hall in San Francisco opened in 1980 and was renovated
A few years ago, the San Francisco Public Utilities Commission (SFPUC) determined that installing a photovoltaic (PV) solar system on the building would benefit the people of San Francisco.
The SFPUC retained engineering consultant AEPC of San Ramon, Calif., to design the PV solar system for the 25,000-square-foot roof.
12' WIDE ROLL-GOOD SYSTEMS
10' Wide Roll-Good Systems
Linear feet of field seams - 5,130
Ponding water on the gym’s existing modified bitumen roof and the built-up roof on several classrooms had created leak problems.
With the buildings in constant use, officials at the church worried an accident would occur where there was a leak, endangering the approximately 175 children that attended the church’s daycare center.
Dodging buckets or closing down the facility in order to make repairs on the roof were not options. At risk from water damage were office and school equipment such as the gym’s brand-new parquet floor.
The majority of roof failures happen at the edge of the building where the wind creates the strongest uplift pressures.
Work schedules were adjusted to meet the symphony’s pre-established rehearsal and performance requirements.
The on-site time and labor saved by the custom-fabricated roofing system helped keep the project on track.
Scheduling commitments at a busy location in the center of the city meant that the materials and equipment could only be delivered and crane-loaded onto the rooftop on weekends.
MOISTURE ISSUES EMERGED
Improper fastening or adhering OF the roof membrane to the
roof deck can lead to potential catastrophic wind damage.
heat-welded together and custom-fabricated to dimensions as specified by the architect, specifier or contractor. Membranes up to 3,000 sq ft.
can be custom-fabricated in a factory setting.
Appeals to architects and engineers who would like to address particular structural or aesthetic design problems.
planning and preparation
Eliminates on-site errors
in the most critical areas.
Dismantling of vocational and technical education
Modified Cap Sheet
3' Wide Roll-Good Systems
Linear feet of field seams - 13,626
for the roofing industry
Workers left construction field in economic downturn
Fewer unions and fewer union apprentices
The most common critical errors include:
Stack flashings for round penetrations are custom-fabricated with a reinforced roofing membrane. The installed roofing membrane is mechanically fastened around the penetration. The flashing is placed around the penetration and the skirt is heat-welded to the roofing membrane for a waterproof seal.
ready for delivery
to the jobsite.
Custom-fabricated membranes and accessories increase a roof’s quality and durability as well as drastically reduce the on-site labor at the most critical areas of a roof.
provide technical support, including CAD services, to create a roof customized to each building's specifications.
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The job was enormous.
It required flashing approximately 400 penetrations, including 126 HVAC units, on five different roof levels.
The school board was impressed by the roofing contractor’s ability to finish the job in just 60 days—less than the estimated timeframe—despite consistently poor weather conditions, which hindered the team’s progress.
Custom-fabrication also helped provide the assurance of
a roof that would be leak-proof and virtually maintenance free, and under the protection of a vigorous warranty.
Specifying a Custom-Fabricated Roofing System
The Ebb & Flow of Construction Labor
There are several reasons why
construction labor decreased.
FLASHING WITH SKIRT
A custom-fabricated two-way air vent allows for both exhaustive and convective movement of air affecting the roofing system.
Easier to install throughout the year, even during adverse weather conditions.
The membrane was custom-fabricated into rolls that were 22 feet wide, reducing the application time and on-site welding.
Penetration flashings, parapet wall membrane, membrane curbs, solar hold down boots, and other related roof materials were all custom- fabricated at the factory.
The company was able to expedite the installation process and meet critical deadlines.
welded into the membrane sheet for attachment to the roof deck.
curbs, stacks, corners, scuppers and pitch pans greatly reduce the risk for installation errors caused by field fabrication while greatly increasing installation efficiency.
6' WIDE ROLL-GOOD SYSTEMS
Better outcome for roofing contractors allowing them to take control of a construction operation in a highly unstable environment.
Construction firms struggle to fill positions:
Significant moisture issues were discovered in the underlying roof insulation, contributing to deteriorating conditions in the 14-year-old tar-and-gravel roof.
The team determined that there was substantial moisture leaking around the HVAC duct support posts that contributed to the saturation of the roof’s insulation.
It’s relatively expensive to turn off and disconnect a solar array and to repair the roof.
Therefore, the owner required the roof life to match the service life of the PV system.
MODIFIED CAP SHEET
3' WIDE ROLL-GOOD
this area, which needs extensive rooftop labor, requires special flashings to ensure the 90 degree change of plane is waterproof.
6' Wide Roll-Good Systems
Linear feet of field seams - 7,968
Codes are critical in all building trades and must be known and considered when making decisions on the rooftop and during preparation of a project.
Remove existing gravel from built-up roof as well as the wet roof and insulation areas.
A ½-inch high-density gypsum cover board was mechanically fastened through the existing roof and insulation, to the concrete deck, which provided a smooth surface for the adhered 60-mil overlay membrane.
This assured the roof met wind uplift as well as seismic design requirements.
For questions regarding custom-fabrication, contact Duro-last at
Survey by The Associated General Contractors of America
In preparation for the large project, the owner of the roofing company spent three days on top of the roof with the membrane manufacturer’s representative estimating the number of deck sheets that would be required. They also measured all of the roof’s penetrations.
As part of the academy’s roof replacement project, a uniquely designed pitched roof was installed on the front of the building, making the new roof impressive not only in terms of necessity and practicality, but also aesthetically.
“We looked at built-ups again, synthetic rubber,
spray-on coatings as well as thermoplastic single-plies.”
— John Nettles, church maintenance director
Officials at Summerville determined that a
custom-fabricated membrane roofing system
would be the best choice.
“Both of these problem roofs had parapet walls to deal with. With the (membrane) roofing system, you can encapsulate the parapet walls to resolve leaking problems that normally occur in walls made of mortar.”
— John Congdon, owner of Congdon Roofing, Inc.
in Charleston, South Carolina
Lack of code knowledge
SAN FRANCISCO, CA
DAVIES SYMPHONY HALL
Working Around Rehearsals and the Streets of San Francisco
12' Wide Roll-Good Systems
Linear feet of field seams - 4,209
HOW ROOFING MEMBRANES ARE INSTALLED
Custom-fabricated membrane sheets can be
mechanically fastened with plates and screws, or adhered.
and time saved
SCHEDULE A "LUNCH & LEARN" WITH DURO-LAST FOR EVEN MORE INFO ON THIS TOPIC AT 800-248-0280
TWO OPTIONS FOR ROOF
READY FOR PV SOLAR
10' WIDE ROLL-GOOD SYSTEMS
– Roofing option that wouldn't produce noise, fumes
– Completed within budget in reasonable timeframe
CUSTOM-FABRICATED SINGLE-PLY MEMBRANE
CHOSEN FOR SEVERAL REASONS:
– Clean & safe application method met requirements
necessary for maintaining classes during installation
– Membrane manufacturer offered
– Mechanical attachment capability
– Competitive pricing
– 15-year warranty option
scope of the project
Workers position the custom-fabricated membrane sheets so that the top membrane overlaps the bottom membrane, ensuring the welding area is dry, clean and free of foreign debris. Workers then hot-air weld the membranes together utilizing a hand held hot-air welder and roller or an automatic welding machine. All field-welded seams must be inspected with a tack claw or similar tool (cotter key extractor), and all deficiencies repaired prior to inspection for
for qualified craftworkers, carpenters, equipment operators, laborers
for qualified roofers
Continuing Education credit can be earned with this labor shortage solution course!
1. DAVIES SYMPHONY HALL - SAN FRANCISCO
2. HEBREW ACADEMY - LIVINGSTON, NJ
3. summerville baptist church - SUMMERVILLE, SC
MATERIAL PREFABRICATION EXPEDITED INSTALLATION
Custom-Fabricated Roofing System - 5' Laps
Custom-Fabricated Membrane Sheets
Linear feet of field seams - 1,278
Solid blue lines represent Duro-Last factory seams.
Custom-fabricated curb flashings are made to fit rectangular penetrations such as HVAC units. These flashings install quickly and eliminate critical seaming from field fabricating parts and pieces together.
In the roofing industry, labor shortages rank as a top concern for contractors. Most rooftop problems are caused by installation workmanship, not material failure.
Skilled Building Labor
in the U.S.
Proper In-field membrane seaming is critical to maintain the watertight integrity of any roof system.
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