A new ASTM International test method aims to prevent air leakage in and around roofs, helping improve energy efficiency, reduce moisture problems and prevent pollutants from entering a building.
“It is critical that each assembly of the building envelope be investigated for air-leakage performance with appropriate standards,” says ASTM Member Sudhakar Molleti. “What cannot be captured in the material and full envelope air leakage testing—the structural strength and continuity of the air barrier assembly—can be quantified in the assembly testing. To achieve energy efficiency of building and to adapt for climate change, comprehensive data of material, assembly, and full envelope air leakage testing are needed. By quantifying air leakage in roof assemblies, this new standard can serve as a platform for supporting code compliance and for constructing energy-efficient and sustainable roof assemblies.”
Molleti, a research officer with more than 10 years of roof assembly testing at the National Research Council Canada, Ottawa, notes roofing membranes are air impermeable but can be compromised by factors, such as lack of continuity of the membrane seams, improper detailing around rooftop preparations, improper selection of flashing materials and improper connection of roof membranes to the exterior wall barrier.
Specifically, this new test method is a laboratory technique to determine air leakage in low-slope membrane roof assemblies and accounts for the wind fatigue expected during the life span of a roof by simulating negative air-pressure differences.
The new standard (soon to be published as D8052/D0852M, “Test Method for Quantification of Air Leakage in Low Sloped Membrane Roof Assemblies”) was developed by ASTM’s committee on roofing and waterproofing (D08).
In other news, a set of proposed ASTM International test methods will help support the growing number of roofing projects that use liquid-applied polymers. The proposed standard (WK40123, “Test Methods for Sampling and Testing Liquid Applied Polymeric Roofing and Waterproofing Membranes that Are Directly Exposed to Weather”) will help manufacturers; testing labs; and the construction industry as they sample, test and compare products. It is being developed by ASTM’s committee on roofing and waterproofing (D08).
The proposed standard includes ways to test liquid-applied polymeric materials that are cured to form roofing and waterproofing membranes that are directly exposed to all kinds of weather. By their nature, these materials are seamless. They are also useful when working with complex surfaces and custom-fit projects.
ASTM Member Philip Moser notes these membranes have been traditionally used for waterproofing of elevated parking decks, but their use for applications like roofing is quickly rising. Moser, a senior project manager specializing in building technology at Boston-based Simpson Gumpertz & Heger Inc., says, “Delivery to the exact point of application in relatively small containers makes these products particularly attractive for small rooftop terraces, congested urban areas and roofs that are not accessible by crane where delivery of larger containers would create logistical problems.”
The test methods would be used by manufacturers and testing labs, as well as the people who write specifications that indicate which test methods should be used to evaluate physical properties.
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RCap Plus utilizes ground and packed granules, and these granules ensure more coverage in the membrane per square. Malarkey grinds the asphalt granules at its South Gate, Calif., manufacturing facility.
The solar reflectivity and limited heat absorption of the RCap Plus cap sheet are key design features of the product. RCap Plus meets CEC Title 24, Part 6 standards and has an initial Solar Reflectance Index (SRI) rating of 87. As part of a roof system, RCap Plus may help decrease energy costs used to cool the building and extend roof service life.
NRCA has released its 2015-16 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 2015 and 2016 projections averaged between $8 million and almost $9 million, respectively, and revealed a near-steady ratio of low- to steep-slope sales of 74 percent to 26 percent.
For low-slope roofs, TPO remains the market leader with a 40 percent share of the new construction market and 30 percent of the reroofing market for 2015. Asphalt shingles continue to dominate the steep-slope roofing market with a 47 percent market share for new construction and a 59 percent share for reroofing.
Polyisocyanurate insulation continues to lead its sector of the market with 80 percent of new construction and 73 percent of reroofing work. In addition, roof cover board installation for 2015 was reported as 22 percent in new construction, 42 percent in reroofing tear-offs and 36 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.
Flat roofs are commonly chosen for industrial and commercial buildings, covering the vast majority of offices, factories and warehouses around the globe. However, despite their popularity, my firm’s experience indicates that the bulk of roofing applications owe to the failings of flat roofs. This begs the question; do the benefits of flat roofs outweigh the disadvantages?
Currently, the flat roofing market is in a particularly healthy state. It is easy to see why because flat roofs do in fact offer a great deal of advantages. Notably, they are a low-cost option for many projects, being easier and more economical to install, inspect and maintain. Therefore, they prove highly popular with many commercial facilities and industrial buildings.
However, flat roofs are historically problematic, suffering from an array of issues commonly arising from standing water and traditional roofing materials. Pooling of water on roofs can be attributed to inadequate roofing materials or, strangely, a roof being “too flat”. Flat roofs should actually feature a small gradient to allow sufficient rainwater run-off; otherwise, the weight of water pooling can lead to deflection and numerous subsequent issues.
Of course, other roof variations, such as pitched or slanted roofs, will offer their own range of complications; however, complications with pooling water are not among these. This distinct disadvantage is one of several that can lead to serious problems within that troublesome 10 percent. The most common problems can be split into three separate categories.
Most roofs form a veritable patchwork of materials, including anything from glass and plastics to masonry and metals. Industrial roofs can be particularly troublesome as they boast a multitude of pipes, heating units and other protrusions that make the roof geometry complex to cover effectively. Whatever the combination of roofing materials is, ensuring long-term adhesion and sealing between all these dissimilar materials is crucial—and can prove problematic.
Flashings fall into this category and are a common fixture of flat and pitched roofs, where metal, brick and felt or bitumen can often all meet. Exposed to varying temperatures and weather conditions, these materials can act differently, altering shape and size dependent upon that material’s characteristics. This can result in roofing weakness due to different expansion and contraction rates of the materials, allowing for water ingress through developing gaps. Moreover, this category includes areas where two metals may meet. Dissimilar metals exposed to continuous weathering can potentially lead to galvanic corrosion, which deteriorates the roof’s protection, loosening the materials and once again leading to issues like leaking.
Joints and Seams
Joints and seams spell considerable trouble for many roofs, predominantly due to the effects of movement. All buildings will feature a degree of movement as a result of thermal expansion, contraction and wind, making joints and seams one of the most vulnerable areas. Resulting gaps or lips can be created, increased further by wind uplift, which may allow water ingress or exposure of unprotected materials to corrosion and weathering.
Similarly, parapet walls can also become vulnerable at the joints, normally caused by movement between the brickwork. This can develop through movement in the building or perhaps vegetation forcing through the joint, widening any gaps further and causing moisture ingress. Furthermore, this problem is shared by the seams around skylights and glazing bars, which degrade over time due to the dissimilar materials present and associated movement.
Unlike other problem areas in this category, cut-edge corrosion does not stem from two materials meeting. In fact, it falls into this category as it is an uncoated seam of metal that, left exposed, will corrode and result in the damage spreading as the metal is slowly eaten away. Corrugated metal roofs are susceptible as they are cut and the edges never receive protection, meaning when cut-edge corrosion begins, it is important to treat it as soon as possible. In certain instances, roof sheets need to be removed and replaced, which is extremely expensive.
Other Forms of Damage
Lastly, roofs are susceptible to various forms of damage in the immediate and long term. Long-term damage will generally arise if roofing is left unmaintained, to suffer from aging and neglect. A key example of this type of damage involves single-ply roof coverings. Over time, rubber roofing materials are subjected to the environment and constant UV exposure. Once again, over this period the material expands and contracts, becoming brittle and losing its former flexibility, making it prone to cracking.
In addition to weathering, wildlife can have a detrimental effect on roofing materials, as bird litter can chemically attack the plastic coating on some roofing systems. High levels can cause damage and subsequent deterioration of the lining, which can potentially lead to leaks or exposure of metal to corrosion.
With regard to immediate damage, working on roofs is also a common way in which damage can occur. As highlighted before, one of the key selling points of flat roofs is the ability to carry out maintenance and inspection easily. Whether it derives from maintenance or rooftop developments, such as HVAC installation, extensions or rooftop fire escapes, the foot traffic over flat roofs can lead to immediate damage of the roofing substrate, through piercing and general wear.
Eliminating the Troublesome 10 Percent
For the majority of these problems, it is possible to find a repair solution. However, when left without treatment, the roof can become too damaged to refurbish, leaving costly replacement as the only option. Repair methods have evolved significantly over the years and eliminating the troublesome 10 percent is becoming far easier to do since the advent of liquid and cold-applied technologies. Not only does this signify a breaking of tradition, but crucially highlights the evolution of roofing maintenance materials.
CertainTeed and ARCOM are pleased to announce that CertainTeed’s roofing product data and customized specifications are now available through ARCOM’s software platforms to architects, engineers and design professionals.
ARCOM and CertainTeed have worked together to create customized versions of the MasterSpec sections to accurately specify CertainTeed’s roofing product portfolio. Along with these specification sections, CertainTeed’s entire roofing product catalog and data sheets are accessible to specifiers when working on their projects.
“We are proud to partner with ARCOM in providing customized roofing specifications for both our Flintlastic Modified Bitumen roof systems and our complete collection of asphalt roofing shingle products,” said Tom Smith, president of CertainTeed Roofing. “These editable, 3-part specifications enable the roof designer to easily produce complete and accurate specifications for both low-slope and steep-slope roofing systems.”
ARCOM and CertainTeed believe this relationship will benefit design professionals as they select and specify roofing products.
CoolStar products meet ENERGY STAR and California Title 24 requirements. CoolStar also qualifies for LEED points and meets NAHB National Green Building Standards.
CoolStar is designed to work with a wide range of roof systems, including built-up roofing, SBS, APP and self-adhering modified bitumen. It is extremely flexible and durable, because of the layering of high-quality reinforcements, heavy asphalt coating and highly reflective ceramic granules. This toughness combats the negative effects of natural expansion and contraction caused by heating, cooling, light and moisture. In addition, the brilliant white CoolStar surface is factory applied for hassle-free, one-step installation, which helps reduce labor costs.
University of Virginia, Rotunda, Charlottesville
ROOFING CONTRACTOR: W.A. Lynch Roofing, Charlottesville
ARCHITECT: John G. Waite Associates, Albany, N.Y.
JOINT-VENTURE BUILDER: Christman-Gilbane, Reston, Va., ChristmanCo.com and GilbaneCo.com
LEAD-ABATEMENT CONTRACTOR: Special Renovations Inc., Chesterfield, Va.
The domed roof required about 6 tons of 20-ounce Flat-Lock copper. W.A. Lynch Roofing sheared 4,000 individual tiles to approximate dimensions in its sheet-metal shop, and a makeshift sheet-metal shop was set up on top of the scaffolding to complete the final measurements and exact cuts.
The University of Virginia was founded by Thomas Jefferson in 1819. Jefferson modeled his design—presented to the university board in 1821—after the Pantheon in Rome. Although he died in 1826 while the Rotunda was still under construction, the stunning building housed the university’s library as Jefferson envisioned.
The rotunda renovation is a two-phase project, and roofing work was part of Phase 1. The roofing team believed seven months was adequate to complete the job; the university, however, requested it be complete by April 2013 so scaffolding would be removed in time for the commencement ceremony. That gave the team a four-month timeline.
Tom McGraw, executive vice president of W.A. Lynch Roofing, explains: “This was just short of impossible even if it wasn’t winter. But as a graduate of UVA, I recognized the basis of the request and agreed to it. So we doubled the manpower and went to a 10-hour day, seven-day a week schedule. We divided the roof into four equal quadrants, each separated by an expansion joint and put a crew in each area working simultaneously with the other three. We also added support personnel in our sheet-metal shop, as well as runners to keep the flow of material to the job site on schedule for the sheet-metal mechanics. In the final analysis, we made the schedule and completed our work within the owner’s request.”
The roofing project was essential because of rust on the previous terne-coated metal roof. It was determined the rust was caused by inadequate roof ventilation that created condensation on the underside of the metal roofing. Ventilation was lacking because of a Guastavino tile dome that was installed in 1895. The condensation was addressed by installing a concealed venting system at the intersections of the treads and risers at the seven steps in the roof, as well as at the top of the dome below the oculus. “Heated air has low density so it will logically rise creating natural convection,” McGraw notes. “This convection creates air movement below the roof and minimizes dead air spaces and the potential for condensation. The key to this is ensuring that you size the ‘intake’ venting similar to the ‘exhaust’ venting so that air will flow in an unrestricted fashion.”
Reroofing a dome can be a challenge, and determining how to keep the interior and its priceless valuables dry required some ingenuity. McGraw invented a tarp that he compares to a hooped skirt to keep the space watertight. The roofing crew cut trapezoidal sections of EPDM membrane and installed them from the bottom to the top of the dome. This skirt-like tarp was configured out of eight pieces at the bottom, six at the midpoint and four at the top. The maximum cut sizes for each level were determined using a computer drawing. Creating the EPDM covering in sections made the tarp easy to handle and remove. “If we seamed it all together or made it in less pieces, the guys wouldn’t have been able to lift it,” McGraw adds.
The tear-off process involved removing the painted metal panels according to lead-abatement standards; the panels were cleaned offsite to maintain the integrity and safety of the job site. A new wood deck was installed on furring over the tiles. This was covered with 30-pound roofing felt and red rosin building paper followed by the new copper roof.
Each piece of copper was tinned and folded before being installed. This process was necessary because of the lack of symmetry on the building. McGraw recalls: “Because this building is almost 200-years old, you have to recognize that not everything is as true and square as one might hope. There are seven steps that circle the base of the dome, and each tread and riser changed in height and width all the way around the building.”
This is the fourth roof for the Rotunda. The first was a tin-plate roof designed by Thomas Jefferson; the second was copper that was a replacement roof after a fire in 1895; the third roof was painted terne-coated steel from 1976; and the current roof is 20-ounce Flat-Lock copper that will be painted white. The decision to select copper was based on cost, durability and historic appearance.
Phase 2 of the project began in May, and the Rotunda will be closed for repairs until 2016. At a price of $42.5 million, utility, fire protection and mechanical upgrades will be made, as well as a Dome Room ceiling replacement and construction of a new underground service vault. The roof also will be painted white, and leaking gutters will be repaired during this phase.
PHOTOS: DAN GROGAN PHOTOGRAPHY
One hundred years ago, M.C. DeThorne established Waukegan Roofing on Philippa Avenue in Waukegan. Although Waukegan Roofing no longer is located on Philippa Avenue, Diederich is grooming his son Philip to someday take over the business. Strange? It gets better: DeThorne included his company’s telephone number—1625—on advertisements discovered by a local historian. Today, Waukegan Roofing’s phone number is (847) 623-1625.
If that isn’t enough, it seems as though Diederich was always meant to own a roofing business. His father owned a shingles-only roofing-contracting firm for 32 years. While he was growing up, Diederich worked for the company but opted to sell roofing materials instead and went to work for Bradco Supply, now Beloit, Wis.-based ABC Supply Co. Inc. Diederich happened to sell materials to Waukegan Roofing, which at that time was owned by Ed and Dave Hiner. The Hiners’ father had bought Waukegan Roofing from the DeThorne family in 1951. When Ed Hiner mentioned in 1998 they were planning to retire, Diederich pulled $5 out of his pocket and jokingly told Ed not to sell before he could speak to his youngest brother who was interested in returning to roofing. The next day Dave Hiner invited Diederich for coffee.
“We were parked next to each other and Dave opened his trunk and said, ‘Ed and I want you to buy our company. Here are the last 10 years of financials,’” Diederich recalls. “I put them in my car and called my wife, telling her she’d never believe what just occurred. She thought they were really serious and urged me to call our attorney and accountant. Thirty days later, I owned Waukegan Roofing.”The Hiners had followed DeThorne’s lead and focused their business on low-slope commercial and industrial roofs. Diederich realized he could offer his shingle heritage to the business. “I looked around and there were all these retail centers being built and they all had a shingle-mansard roof of some form,” he says. “I approached Waukegan Roofing’s top-five contracts and asked what they thought about me starting a shingle division. Every one of them said it would be a great idea because they could come to Waukegan Roofing for everything, not just the flat part of the roof.”
Waukegan Roofing’s shingle division has been very successful since Diederich established it in 1998. Today, the firm constructs all types of low- and steep-slope roofs, along with roof-related sheet metal. In addition, in 2007, Diederich started a commercial service and maintenance division, which kept Waukegan Roofing busy through the economic downturn and benefitted the company’s growth overall.
Diederich credits his 55 union employees with his company’s success. “We stick by them through thick and thin,” he says. “We just believe in the people who work for the firm and in the quality of the product we put out. Our motto is ‘Installing roofs you can rely on’, and we believe in that wholeheartedly.”
All the clues that Diederich’s chosen profession was meant to be are there, and he agrees his life has come full circle—from working in his dad’s roofing business to helming a successful roofing contracting company of his own into its 100th year. “People ask me whether I regret buying a roofing company and I say, ‘Yeah, I wish I would’ve done it 10 years earlier’,” he chuckles.
Bruce Diederich is immediate past president of the Chicago Roofing Contractors Association. He also is an active member of the Midwest Roofing Contractors Association and National Roofing Contractors Association.