An ongoing environmental endeavor

Wm. Molnar Roofing reroofs Wilson Middle School

  • Wilson Middle School's existing roof system before R.K. Hydro-Vac removed the stone ballastPhoto courtesy of Wm. Molnar Roofing Inc., Riverview, Mich.
  • An aerial view of Wilson Middle School during reroofingPhoto courtesy of Wm. Molnar Roofing Inc., Riverview, Mich.
  • Wilson Middle School's new white TPO roof systemPhoto courtesy of Wm. Molnar Roofing Inc., Riverview, Mich.
  • A vegetative roof system installed on one roof sectionPhoto courtesy of Wm. Molnar Roofing Inc., Riverview, Mich.

The Wyandotte Public Schools District of Wyandotte, Mich., serves more than 4,700 students and includes six elementary schools, a middle school, high school, administration building, skills center and regional training center.

During the past decade, the school district has entered into three consecutive performance contracts with Johnson Controls, Glendale, Wis., which allow major building improvements to be funded by the energy and operational savings created by new equipment installed as part of the performance contracts. So far, these contracts have provided numerous building and energy-efficiency improvements and saved the school district $6.9 million.

Through the performance contracts, Johnson Controls has replaced windows and doors at the district's high school, upgraded and enhanced the building's heating and cooling systems, and installed building management systems at all the district's schools. Additionally, in 2008, part of the roof system on the district's Wilson Middle School was replaced, and a 10.8-kilowatt (kW) photovoltaic (PV) system was installed. Johnson Controls subcontracted Wm. Molnar Roofing Inc., Riverview, Mich., to install the PV system.

"The solar panels were furnished by Kulick Enterprises, Wyandotte," says Rob Molnar, estimator and project manager for Wm. Molnar Roofing. "There were 54 panels held by three racks. The system required 38 stanchion supports that penetrated the low-slope EPDM roof system. Kulick Enterprises located the penetrations and we cut the holes, attached the stanchions to the iron joists and flashed the supports into the existing roof system. We then used our crane to lift the panels and place them on the racks."

In June 2009, Wm. Molnar Roofing had another opportunity to work with Johnson Controls and Wilson Middle School; a portion of the school's remaining roof system—which was suffering from leaks associated with significant ponded water—needed to be reroofed.

"Johnson Controls wanted a white TPO roof system with a 20-year warranty so it could guarantee payback to Wilson Middle School during a 20-year period." Molnar says. "Wm. Molnar Roofing and a local competitor were selected to recommend a roof system to Johnson Controls and bid accordingly."

The bid process

In addition to requiring a TPO roof system with a 20-year warranty, Johnson Controls wanted Wilson Middle School's new roof system to have an insulating R-value that would help meet the school district's energy payback criteria—which was not specified to Wm. Molnar Roofing—and be economically feasible.

"I started with a test cut and measurements," Molnar says. "Next, I searched for a TPO roof system that was warrantable regarding the specified conditions. I enlisted the help of Sean Metcalfe of North Coast Commercial Roofing Systems, Southfield, Mich., a commercial roofing distributor."

Metcalfe helped Molnar select a Carlisle SynTec TPO roof system for the project.

"Once we selected the system to offer, we bid the project accordingly," Molnar says. "Our base bid was to remove all existing roofing materials to the lightweight concrete fill; mechanically attach a modified base sheet to the concrete fill; and set one layer of 1 1/2-inch-thick polyisocyanurate insulation in hot asphalt followed by a full layer of 1/4-inch-per-foot tapered insulation set in hot asphalt, including all 1/2-inch-per-foot tapered saddles between all drains and walls. We then installed a 60-mil-thick fully adhered white reinforced TPO membrane.

"Shortly before the project began, Bill Molnar Jr., Wm. Molnar Roofing's field superintendent, recommended we use Carlisle SynTec's FAST 100 adhesive to attach the base layer of insulation directly to the lightweight concrete fill; this would eliminate labor associated with first installing a base sheet over the lightweight concrete fill, as is required when set in hot asphalt," Molnar continues.

Wm. Molnar Roofing's bid also specified building a 12-inch wood-framed wall to accommodate the roof's new slope; removing all abandoned roofing equipment and filling in the voids with decking; raising all curb heights to an 8-inch minimum; and installing walkway pads around the roof hatch. Additionally, the company offered cost-effective alternatives such as using 1/8-inch-per-foot tapered insulation and a ballasted system instead of 1/4-inch-per-foot tapered insulation and a fully adhered system.

"I used NRCA's EnergyWise Roof Calculator Online to give Johnson Controls' engineers a basis for the estimated payback figures so they could compare our base bid's potential payback with that of several alternatives, the existing roofing materials and possible alternatives from our competitor," Molnar says. "According to the calculator, a 1/4-inch-per-foot tapered polyisocyanurate insulation layer installed over a 1 1/2-inch-thick polyisocyanurate layer would provide an average R-value of 33.6; the calculator estimated this would save the school a significant amount of money annually during the roof system's life compared with the existing roof system."

Three weeks after Wm. Molnar Roofing submitted its bid, Johnson Controls informed the company it wanted to proceed with the base bid.

Molnar says: "In less than five business days, we executed the contract, ordered and provided payment and performance bonds, sent submittals, ordered materials, created a project manual for the field supervisors and mechanics, and scheduled a pre-construction meeting."

Performing work

A Wm. Molnar Roofing crew of 14—including two safety monitors, various roofing workers, a kettle operator, crane operator and supervisor—began work at Wilson Middle School June 15. The crew's first task was tearing off the existing 26,000-square-foot roof system, which consisted of 3 1/2-inch-thick extruded polystyrene, loose-laid EPDM and stone ballast.

"The project's tear-off process included 100 percent recycling of materials," Molnar says. "R.K. Hydro-Vac, Piqua, Ohio, removed the stone ballast, which was deposited at the Wyandotte Department of Public Services site to be reused by the city."

Wm. Molnar Roofing then cut the EPDM into sections and lifted them to the ground, where they were placed on pallets and taken away by Nationwide Foam Inc., Framingham, Mass., to be recycled.

"Nationwide Foam also recycled most of the extruded polystyrene," Molnar says. "However, we kept about 50 squares of it, which some of our employees took home to insulate their garages.

"Finally, the sheet-metal components from the existing system were removed and delivered to Fritz Enterprises, Taylor, Mich., for recycling," Molnar continues.

After R.K. Hydro-Vac removed the ballast, roof system tear-off proceeded simultaneously with the new roof system's installation.

"An unknown factor was the condition of the lightweight concrete fill," Molnar says. "We provided an additional unit cost amount for removing and replacing any unsound or deteriorated material. But, fortunately, the existing lightweight concrete fill was in good condition and did not require any unit cost replacement. After discovering this and realizing the cost savings for Johnson Controls, I approached the company and asked whether we could install a small vegetative roof system on one roof section. In the spirit of 'going green,' Johnson Controls agreed."

To alleviate the existing roof system's ponded water issue, Wm. Molnar Roofing installed a full 1/4-inch-per-foot tapered insulation system to ensure positive drainage.

"This created a 12-inch height difference from the previous height of the wood nailer/gravel stop," Molnar says. "We built a 12-inch wall with No. 2 pine, a 2- by 4-inch base plate and top plate with 2- by 4-inch studs at 16 inches on center. We also installed 5/8-inch-thick plywood on the new wall's exterior and interior.

"I thought a one- or two-piece gravel stop/fascia would be subject to oil canning, even with pressure bends, so I decided to use a vertical flush panel system, which partially was covered by a two-piece snap-on gravel stop required for Carlisle SynTec's 20-year TPO warranty," Molnar continues. "All materials were 24-gauge prefinished Kynar 500® steel except the continuous gravel stop cleat, which was 20-gauge galvanized steel."

Wm. Molnar Roofing employed a full-time ground safety monitor for the project, as well as a full-time rooftop safety monitor. The company also used a Blue Water Manufacturing Kwik-Stand warning line system, which included 24 stands and 900 feet of red and yellow flags.

"Stands and rails were set up where the kettle pipe was brought to the roof, as well as where lifting, loading and unloading were taking place," Molnar says. "Harnesses and lanyards were worn by mechanics working from the aerial lift, as well as those working outside the warning line."

And though safely storing materials and equipment can be challenging at an educational facility—especially one with children present—Molnar says this was not a problem during the project.

"To keep materials from being a hazard or an object of horseplay, we stored most materials on the roof, where they were tarped and weighted down."

A learning tool

Wm. Molnar Roofing finished installing Wilson Middle School's new roof system June 26.

"The biggest challenge for us was finding a cost-effective method to leave the lightweight concrete fill in place, adequately attach the insulation and still achieve a 20-year warranty," Molnar says.

The finished roof system, as well as the PV roof system installation and other changes made through the performance contracts, have helped the Wyandotte Public Schools District become the first district in Michigan to be fully certified by the U.S. Environmental Protection Agency's ENERGY STAR® program.

Molnar is proud to have played an important role in helping the school district achieve the certification.

"Everyone was great to work with," Molnar says. "It was a pleasure to be part of the Johnson Controls team. And it was rewarding to be able to design, engineer and install a diverse system that sets us apart from our competitors."

Ashley St. John is Professional Roofing's associate editor.

Project name: Wilson Middle School
Project location: Wyandotte, Mich.
Project duration: June 15, 2009-June 26, 2009
Roof system type: TPO, vegetative and photovoltaic
Roofing contractor: Wm. Molnar Roofing Inc., Riverview, Mich.
Roofing materials manufacturer: Carlisle SynTec Inc., Carlisle, Pa.


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