RhinoBond Hits the Airways over New Hampshire Public Television
Since 1959, New Hampshire Public Television has provided programs and services for the Granite State and northern New England. The station reaches nearly 500,000 households each week, broadcasting more than 7,000 hours of PBS and locally produced programming each year. In addition, it provides educational services and resources for educators, parents and students as well as community engagement initiatives.
NHPTV’s Broadcast Center in Durham is home to state-of-the-art digital production and broadcast equipment. So when it was time to re-roof the facility, it was critical to find a roofing solution that could be installed quickly and quietly to minimize interruptions to the on-site production work, broadcasts, tapings and the station’s fundraising activities.
The NHPTV building is a two-story facility with an EIFS facade. The 13,000-square-foot roof has a low parapet wall, several drains as well as various vent, pipe and equipment penetrations. In addition, there is a large air handling unit and an array of sophisticated antenna and dishes on the roof. A raised “A-frame” skylight that provides substantial natural daylight into the facility runs the width of the structure.
As the building’s original ballasted EPDM roofing system was nearing the end of its useful life, the station began looking for a new roofing system. Besides a system that could be installed without disrupting the occupants, the station also needed a system with a minimum amount of fasteners that penetrated the roof deck.
The underside of the structure’s steel deck is covered with acoustic fibers over its studios. In addition, a significant amount of conduit is attached to the underside of the deck which had to be avoided during the installation.
New England Weather & Roofing Production
Advanced Roof Management (ARM), a 17-year-old roof consulting firm based in North Hampton, N.H., was hired as the consultant for this project. Plans and specifications were developed for a conventional fully adhered assembly as well as an alternative system using a less intrusive attachment method.
“Right from the start, I had something different in mind for this building,” explained Steve Burns, president of ARM. “For nearly a year, I’ve been reviewing and researching the RhinoBond System from OMG Roofing Products. I really like the way that RhinoBond spreads the wind uplift load across the roof, as well as the speed with which contractors can dry-in the roof using this system. So I decided to bid the RhinoBond System against a conventional fully adhered assembly to see how the numbers matched up.”
When the bid from A&M Roofing Services of Andover, Mass. came in substantially lower for the project using the Sika Sarnafil RhinoBond System with a 60 mil white PVC membrane, Burns was very pleased.
RhinoBond is an alternative attachment system for installing TPO and PVC membranes. The system eliminates membrane fastener penetrations by welding the membrane directly to specially coated plates used to secure the insulation or cover board to the deck. The result is a roofing system that uses fewer plates and fasteners while enhancing the wind uplift resistance.
“I thought that this was a great project for RhinoBond,” said Burns. “It met all of the project criteria and could be completed without disrupting New Hampshire Public Television’s operations.”
A&M Roofing Services is a 31-year-old full-service commercial roofing contractor that specializes in both low and steep slope work. They had previous experience with the RhinoBond System and Craig Brecht, vice president at A&M, thought that this project was well suited for the system.
“We felt very good about the alternative bid with RhinoBond and know that the Sika Sarnafil System has an excellent reputation in the market,” said Brecht.
The RhinoBond System uses a patented stand-up induction welding tool to bond the underside of the membrane to the specially coated plates. Welds typically take five seconds each to complete and a magnetic cooling clamp is immediately placed onto the welded plate to assure a strong bond. For a roof system requiring a 1-90 rating, the system requires ten fewer fasteners and plates per square when compared to a typical in-seam mechanically-attached system using a 10-ft.-wide membrane fastened 12-inches on center.
The project entailed tearing off the existing 20-year-old ballasted EPDM roof. Since the material was loose laid, it was easy to remove the ballast and the rubber without disrupting the insulation.
“Since the existing three-inch polyisocyanurate was in good shape,” said Brecht, “the plans called for leaving it in place and covering it with a layer of ½-inch DensDeck.”
In addition to adding the cover board, A&M also expanded the roof drain sumps for better drainage, increased the width of the parapet wall to better tie-in to the building’s exterior and installed coping cap.
“As with any system, there’s a learning curve with RhinoBond,” said Brecht. “The tool itself is very easy to understand and use, but you have to approach the project from a slightly different perspective, and you have to layout the roof differently.”
The key is determining how many fasteners are required per square based on the desired wind design. For the NHPTV project, six fasteners were installed per 4 x 8 ft. board in the field of the roof with enhanced fastening at the perimeter per Factory Mutual requirements.
“After the tear off was completed, we laid out the cover board. With the RhinoBond System, it’s important to install the fasteners in a nice even grid, so when they are covered by the membrane, you can easily find them. For expediency, we snapped lines on the cover board, which we normally don’t do,” said Brecht.
The grid pattern distributes the uplift load over the entire roof surface rather than having it concentrated in the seams in a linear fastening mode. This reduces the likelihood of point loading and minimizes sheet flutter. Furthermore, with this system, membrane width is not an issue and perimeter half sheets are not needed.
New England’s weather during the summer of 2009 was awful, with record amounts of rain and only limited days for roofing activity.
One of the benefits of the RhinoBond System is that in certain circumstances, the membrane can be completely installed, seamed and have all the details finished before all of the plates are bonded to the membrane. This was the case for the NHPTV project.
“The weather was an on-going challenge but we still achieved strong production rates,” said Brecht. “We installed the roof and got the building dry before completing all of the RhinoBond welds. The Sika- Sarnafil membrane is easy to work with and we were on and off the roof in only four days.”
“It’s a great roofing system,” said Burns, “and definitely the right solution for NHPTV.”