Prefabricated Edge Metal Helps Shape Unique Roofs on a Georgia Hospital

To expand its services and make it easier for patients and visitors to navigate its facility, Gordon Hospital, Calhoun, Ga., underwent a $37 million expansion. The project added 59,000 square feet of hospital space, renovated 11,500 square feet of space, and created a new patient tower entrance to separate inpatient and outpatient service entrances. The various aspects of the project included 11 different roof areas, so the project’s general contractor, the Atlanta office of Birmingham, Ala.-based Brasfield & Gorrie, brought Atlanta’s Diamond Roofing Co. into the project during concept design.

The architects designed all the curves and unique walls to make the campus beyond ordinary and give the hospital a certain appeal.

The architects designed all the curves and unique walls to make the campus beyond ordinary and give the hospital a certain appeal.

“The hospital addition and renovation was still just a sketch and a narrative, and we worked together to understand the owner’s needs and architect’s intent,” says Dave Mossige, Diamond Roofing’s president. “Roofing systems have be- come very complex over the years and it really does take a roofing specialist to navigate the numerous options and decide the best roofing systems for the project.”

Having the roofing contractor onboard from inception also helped with staging. When it became apparent that two canopies between the new and existing buildings would pose significant challenges with materials’ access, the team was able to plan ahead and stock-pile materials near the area months pri- or to needing them.

GETTING THINGS LEVEL

Because this was a fast-track project, 10 to 15 crew members worked across multiple roof areas. “All the other trades come in behind us once we have the roof ready, so getting the roof area dried-in was key to the schedule,” Mossige says. “That’s why we chose a more durable two-ply modified bitumen rather than a single-ply system for the roofing. Disturbances that happened to the base while the trades were working off the roofs could be quickly and easily repaired before we applied the cap sheet.”

The roofing areas added up to 25,400 square feet of space, including the main roof, penthouse and various other canopies. The main roof on the new addition was unique because it was divided into two portions: one with a steel deck and another with a concrete deck for future vertical expansion. The concrete deck was 5-inches higher than the steel deck.

To make the steel deck meet the thickness of the adjacent concrete deck for a level roof, Diamond Roofing’s team mechanically fastened 5 inches of polyisocyanurate insulation on the steel and then installed a 1/4-inch-per-foot-total tapered ISO system. The team then applied a cover board to increase the system’s wind rating and provide better adhesion of the base ply. The tapered system and cover board were set in ribbons of low-rise foam adhesive. The next layer was an SBS modified bitumen as a cold-process adhesive and then a fire-rated granular cap sheet, also set in a cold-process adhesive.

Although Diamond Roofing has a sheet-metal shop in which team members fabricate edge metal, it worked with a supplier to source prefabricated edge metal that had been formally tested to meet or exceed the hospital's required FM 1-105 criterion.

Although Diamond Roofing has a sheet-metal shop in which team members fabricate edge metal, it worked with a supplier to source prefabricated edge metal that had been formally tested to meet or exceed the hospital’s required FM 1-105 criterion.

PRECISE EDGE METAL

Although Diamond Roofing has a sheet-metal shop in which team members fabricate edge metal, most of the roofing firm’s product is equivalent to a wind rating of FM 1-60 and FM 1-90. FM approval ratings apply to uplift pressures in pounds per square foot. Hospitals are constructed to stricter standards, however, and officials at Gordon Hospital wanted to ensure an FM 1-105 approval rating. Diamond Roofing worked with a supplier to source prefabricated edge metal that had been formally tested to meet or exceed the FM 1-105 criterion.

The ability to order the sheer volume of edge metal needed also saved time on the project. “We had over 2,500 lineal feet of edge metal on this project. That would’ve taken us three weeks to fabricate,” Mossige explains. “In addition, the highly unique specifications of the edge metal needed for the project made it more cost-effective for us to outsource it.”

The edge metal needed to be a heavy gauge of 0.063 prefinished aluminum with a protective Kynar 500 resin-based coating. The architects also wanted welded mitered corners. In certain places on the roofs, unusual radiuses and slopes—occasionally joining with straight coping at offset angles—meant some inside and outside miters had to be exactingly produced for odd angles like 104 and 140 degrees.

For example, on one parapet, two different elevations come together at a corner, making precision critical for the manufacturer and installer. “When you are dealing with preformed metal, you have to be precise,” Mossige notes, “but when you’re doing a raised, offset miter, you have to be perfect.”

PHOTOS: OMG EDGESYSTEMS

Pages: 1 2

Membrane Is Factory Laminated to Cover Board

SOPREMA Inc. has developed SOPRASMART Laminated Boards, which combine SOPRALENE SBS-modified bitumen membrane and cover board into one installation layer, resulting in application consistency and complete adhesion.

SOPREMA Inc. has developed SOPRASMART Laminated Boards, which combine SOPRALENE SBS-modified bitumen membrane and cover board into one installation layer, resulting in application consistency and complete adhesion.

SOPREMA Inc. has developed SOPRASMART Laminated Boards, which combine SOPRALENE SBS-modified bitumen membrane and cover board into one installation layer, resulting in application consistency and complete adhesion. SOPRASMART is manufactured in a controlled setting, utilizing heat-welding equipment to laminate the SBS-modified bitumen coating of the base ply to the desired cover board. This eliminates the risk of delamination or wrinkling, and the sealed overlap protects the assembly from open flame intrusion when torch welding. SOPRASMART is available in a variety of cover-board options, including SOPRABOARD, high-density polyisocyanurate foam board, gypsum panels and high-density rock wool. It can be mechanically fastened or adhered using the DUOTACK adhesive.

NRCA Releases Market Survey on Sales Volume Trends

The National Roofing Contractors Association (NRCA) has released its 2014-15 market survey providing information about overall sales volume trends in the roofing industry, roofing experiences, material usage and regional breakdowns. It is an important tool to measure the scope of the U.S. roofing industry, and the data provides a glimpse into which roof systems are trending in the low- and steep-slope roofing markets.

This year’s survey reports sales volumes for 2014 and 2015 projections averaged between $7 million and just more than $8 million, respectively, and revealed a near-steady ratio of low- to steep-slope sales of 72 percent to 28 percent.

For low-slope roofs, TPO remains the market leader with a 31 percent share of the new construction market and 26 percent of the reroofing market for 2014. Asphalt shingles continue to dominate the steep-slope roofing market with a 44 percent market share for new construction and a 58 percent share for reroofing.

Polyisocyanurate insulation continues to lead its sector of the market with 75 percent of new construction and 70 percent of reroofing work.

In addition, roof cover board installation for 2014 was reported as 24 percent in new construction, 46 percent in reroofing tear-offs and 30 percent in re-cover projects.

NRCA’s market survey enables roofing contractors to compare their material usage with contractors in other regions, and provides manufacturers and distributors with data to analyze, which can affect future business decisions.

Georgia-Pacific Gypsum’s Durable Cover Board Outperforms High-density ISO in Puncture and Hail Testing

Third-party testing results confirm that Georgia-Pacific Gypsum’s DensDeck Prime Roof Boards display puncture and impact resistance, protecting thermoplastic roofing membranes better than high-density polyisocyanurate (HD ISO) cover boards.

All types of commercial roofing membranes are susceptible to everyday punctures from a variety of sources. Rigid objects with sharp edges like dropped tools; heavy equipment; winds which blow branches and debris onto roofs; and frequent foot traffic for general maintenance and repair can cause punctures at any time, explains Todd Kuykendall, director of marketing and product management, Georgia-Pacific Gypsum. “DensDeck Prime cover boards support membranes so they can resist puncture damage, allowing them to do their job as the front-line protection of the roof assembly against water intrusion.”

Thermoplastic membranes tested in assemblies with 1/4-inch DensDeck Prime boards underneath were 83 percent more puncture resistant than membranes with 1/2-inch HD ISO or with no cover board at all, based on average calculations.

Thermoplastic membranes tested in assemblies with 1/4-inch DensDeck Prime boards underneath were 83 percent more puncture resistant than membranes with 1/2-inch HD ISO or with no cover board at all, based on average calculations.

The independent ASTM D5635 puncture test results indicate that thermoplastic membranes do not puncture as easily when 1/4-inch DensDeck Prime Roof Boards are used as a cover board, as compared with HD ISO boards. Puncture-resistance testing conducted by Jim Koontz & Associates, July 21 to August 1, 2014, in its Hobbs, N.M. laboratory, according to ASTM D5635 standards. Assemblies included a base layer of 2 inches, 20-psi polyisocyanurate insulation; and configurations were covered with 45-mil thermoplastic polyolefin (TPO) or 48-mil polyvinyl chloride (PVC) membranes. The test method evaluates the maximum puncture load the samples can withstand, without allowing the passage of water when subjected to impact from a rigid object with sharp edges. Thermoplastic membranes tested in assemblies with 1/4-inch DensDeck Prime boards underneath were 83 percent more puncture resistant, on average, than membranes with 1/2-inch HD ISO or no cover board at all.

Durable and versatile DensDeck Prime roof boards can potentially save money for roofing contractors, building owners and facility managers by eliminating or reducing the need for costly repairs due to punctures during and after completion of the roof installation, Kuykendall adds, “In these puncture tests, HD ISO performed similar to no cover board at all, allowing thermoplastic membranes to puncture more easily.”

Thermoplastic membranes tested in assemblies with 1/4-inch DensDeck Prime boards underneath were 83 percent more puncture resistant than membranes with 1/2-inch HD ISO or with no cover board at all, based on average calculations.

In addition to puncture resistance testing, the independent company also conducted tests simulating the impact of hail in a variety of roofing scenarios—and the results were similar.

Performance of 1/4-inch DensDeck Prime roof board versus HD ISO or no cover board at 1.5- to 2.5-inch hail ball impacts. Assemblies in these tests with thermoplastic membranes and high-density ISO cover boards demonstrated 25 to 30 percent greater indentation than similar tests with DensDeck Prime roof boards.

Performance of 1/4-inch DensDeck Prime roof board versus HD ISO or no cover board at 1.5- to 2.5-inch hail ball impacts. Assemblies in these tests with thermoplastic membranes and high-density ISO cover boards demonstrated 25 to 30 percent greater indentation than similar tests with DensDeck Prime roof boards.

FM 4473 (using NBS— National Bureau of Standards—23 standards) hail test results indicate that DensDeck Prime boards offer key benefits against hail damage versus HD ISO products. Hail testing (or impact resistance testing of rigid roofing materials by impacting with freezer ice balls) conducted by Jim Koontz & Associates July 21 to August 1, 2014, in its Hobbs, N.M. laboratory, according to FM 4473 (using NBS 23 standards). Based on average results using 1.5- to 2.5-inch freezer ice balls. Assemblies included a base layer of 2-inch 20-psi polyisocyanurate insulation; and configurations were covered with 45-mil thermoplastic polyolefin (TPO) or 48-mil polyvinyl chloride (PVC) membranes.

  • Less likelihood of membrane damage — Assemblies with DensDeck Prime panels exhibited less indentation that stressed the membrane and can potentially result in membrane failure;
  • More resilience during hail events — Assemblies with DensDeck Prime panels withstood larger hail sizes that may cause cover board fractures.

Performance of 1/4-inch DensDeck Prime roof board versus HD ISO or no cover board at 1.5- to 2.5-inch hail ball impacts. Assemblies in these tests with thermoplastic membranes and high-density ISO cover boards demonstrated 25 to 30 percent greater indentation than similar tests with DensDeck Prime roof boards.