Designing Resilient Single-Ply Membrane Roof Systems for Hot Climates

Photo 1: The Temple of Karnak, Luxor, Egypt: The ancients learned by experience that shade in association with ventilation provided comfort.

The growing popularity of increased thermal insulation, in association with code and standard mandates, assists in mitigating exterior ambient temperatures and heat flow migration influences on building interior environments. Some have tried to mitigate these exterior influences on the interior by roof surface color alone — an incorrect precept. Roof color alone, an attribute of a single roof system component, cannot mitigate exterior influence in and by itself. Insulation, roof system design, roof deck, etc., all have a role to play.

To make matters worse, HVAC designers have not been informed as to how roof system design can detrimentally affect HVAC performance. Increased air temperatures above the roof surface, high-temperature heating of rooftop piping, and the heating of rooftop units by reflection of the roof surface have all resulted in HVAC performance well below that for which it was designed.

Photo 2. The Greeks learned to use mass to mitigate high levels of solar radiation and resultant heat flow to maintain interior comfort. Shown here is the architecture on the Greek Island of Santorini.

The roof system is made up of various components, which can include some or all of the following: roof deck; substrate board; vapor and/or air barrier; thermal insulation layers; the insulation adhesive or mechanical fasteners; spray foam insulation sealer; cover board; cover board adhesive or mechanical fasteners; roof membrane; membrane adhesive or mechanical fasteners; and roof cover of ballast or coating. Thus, the function of the roof is not a single component effect, but the sum of the whole — all components working together in association with building type, interior use, and location.

Appropriate roof system design is the result of the architect, engineer and building owner working together, taking into consideration the function of the building and the effects of the climatic and environmental conditions expected to be experienced.

This article explains the effects of roof system design on HVAC design in hot climates from the perspective of a roof system designer. It is based on a paper I delivered at the 2014 ASHRAE International Conference on Energy & Indoor Environment for Hot Climates in Doha, Qatar. Its lessons are even more relevant today, with the increase in ambient temperatures worldwide. Concerns such as heat flow, reflected ultraviolet light effects, rooftop temperatures and their potential detrimental effects on HVAC performance will be reviewed. Design recommendations and detailing suggestions for achieving long-term roof service life performance in hot climates with single-ply membranes will be explored. Proactive design recommendations for HVAC designers on how to deal with roof-borne effects will also be provided.

Environmental Concerns Lead to Changes

Societal concerns for the environment, which led to the development of the Leadership in Energy and Environmental Design (LEED) program under the auspices of the United States Green Building Council (USGBC) promoted the use of “cool roofs” — now referred to as “reflective roofs” — as both a potential energy conservation and urban heat island reduction methodology. This movement led to legislative and code mandates that became drivers for massive changes in the roofing industry. Consequently, the use of reflecive roof membranes, which are defined by the U.S. Environmental Protection Agency’s Energy Star program as roof covers with an initial solar reflectance of 0.65 or greater, have become the code-mandated choice that architects have when designing low-slope roof systems. The specifying of reflective roof membranes — albeit with little forethought in their use and implementation into a roof system — resulted in unintended consequences, such as the formation of moisture below the membrane, excessive heat production to rooftop equipment and building components, and premature failure of some roof systems.

(FIGURE 1A) Figures 1A and 1B: A vented and ballasted roof system not only shades the roof cover, but provides a ventilation layer allowing warm air to rise and dissipate from the roof, thus reducing heat gain to the interior.
(FIGURE 1B)

The goal of cool roofing has moved over the past years from a potential energy-saving roof cover to an urban heat island mitigator. The challenge for the building design community is to realize that if energy savings is the goal, ballasted roofs are the best choice, as research shows that cool roofs actually raise the ambient temperature above the roof surface. Additionally, reflected UV rays are heating rooftop piping. Clearly in hot and sunny climates, reflective roofs are not in the best interest of the HVAC system performance.

As with any roof-cover material, the appropriate design and use of the material is required to achieve long-term success and a truly sustainable roof system. Roof-system design is equal in importance to structural, mechanical, plumbing and electrical design. Therefore, it is imperative that designers who utilize single-ply cool roof systems, especially those which fall within American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Climate Zones 4 through 7 (approximately from the state of Tennessee north), take extra care to achieve a properly functioning and sustainable low-slope roof system. Efforts have recently been made to raise the mandate for reflective roof surfaces to include ASHRAE Climate Zone 4. While this author firmly believes that the selection of a roof system (no matter the climate zone) should be the decision of the architect and owner, raising the mandate to Climate Zone 4 would be imprudent and result in little if any energy savings, with increased potential for roof system failures.

Optimal HVAC Performance in Hot Climates

HVAC cooling equipment design in hot climates often utilizes over-design to compensate for the building’s thermal gain and heat on the roof. Another often overlooked aspect of rooftop equipment is the drop-off in efficiency due to cooling loss in the ductwork and piping; as a result of solar gain, heat and exacerbation from cool roof surfaces that reflect rays back up at the piping can “superheat” the pipe/duct contents.

If the roof cover temperature can be reduced, and the roof’s effects on ducts and pipes can be reduced, the efficiency of roof op equipment will rise, units can be reduced in size, and operating costs will be reduced.

Roof System Requirements

Roof system design should take into consideration the climate and micro-climates in which the roofs are to be located. This is often not the case, with architects simply selecting a roof system by its warranty length and how many LEED credits it can procure. This lack of design methodology has kept many a forensic roof consultant busy, owners frustrated, and manufacturers unsettled, as failures are frequent and mitigation costly.

IMAGE: HUTCHINSON DESIGN GROUP LTD.

The need for climatic considerations is exacerbated when the roof system will be located in geographical areas of extreme weather: high winds, extreme cold, and extreme heat. For the purposes of this paper the climatic parameters to be considered are:

  • Extreme heat
  • Intense ultraviolet radiation
  • Sand erosion

Thus, to be successful, the roof cover (membrane) must resist these forces for the term of the desired service life. This author believes in designing with long-term service life in mind. Long-term service life is the essence of sustainability, and in this author’s opinion is a minimum of 30 years.

Heat aging and deterioration of roof membranes from ultraviolet radiation has been the bane of roof covers for decades. Premature end of service life as a result of these effects has been well documented by professionals, studied by researchers, and experienced by building owners.

The effects of windblown sand across, or accumulation upon, roof membrane is less understood, but as a rough-surfaced material moving across a pliable membrane it is intuitive that this action could be egregious to the long-term performance of the roof membrane.

Consequently, to achieve long-term performance in hot climates, the roof membrane, in addition to meeting all the needs of the building and roof system, must have a history of resisting long periods of high ambient temperatures, and high surface temperatures, and be resistant to the effects of ultraviolet radiation.

Lessons From History

Learning from historical examples from indigenous peoples who had to deal with the climate with fewer tools than are available today is both prudent and wise. Cultures in the Middle East have dealt with extreme heat is several ways. The first is through shade. While exposed to the sun, hot and arid ambient climates are almost unbearable. Indigenous people first protected their skin with “galabeyas,” a traditional garment. For structures, shade became a key design element. This can be observed in many of the ancient Egyptian structures that have been uncovered and are viewable today. The Temple of Karnak along the Nile in Luxor is one fine example. (See Photo 1.)

Photo 4: At Queen Alia International Airport in Jordan, architect Norman Foster utilized ventilation cavities below the metal roof systems to vent out any possible build-up of heat. Photo credit: Markus Mainka – stock.adobe.com

The Temple of Karnak also provides us with a second example of a method used as protection from the heat and sun, which is to cool via ventilation. The tall columns of the various halls provided needed structure, but also induced air movement. This concept was integral in the design of the Jeddah Airport in Saudi Arabia.

Wall and roof construction across the Mediterranean, not only in the European cultures, but also in the Asia Minor, Middle Eastern, and Northern African cultures, utilized thick, massive walls that could absorb the heat of the day and prevent it from moving to the interior — a cave above ground, if you will. (See Photo 2.)

Thus, we learn from history that the following were important design features in providing comfort in extremely hot and arid climates:

1. Shade

2. Ventilation

3. Mass

In translating the historical precedents in regard to roofing to today’s building needs and roof systems, the issue of shading needs to be given more consideration. In the United States, the current roof systems that offer shading are ballasted assemblies with river-washed gravel of approximately 1.5 inches in diameter (3.8 cm). Spread at a minimum of 10 pounds (4 kg) per square foot(30.5 cm2), the stone creates a shading layer over the roof membrane below. The stone ballast also creates a mass element that can absorb the sun’s energy. While the stones lying next to each other create voids and spaces, the ventilation element is small, but present. In order to achieve the ventilation element, a drainage mat (used in garden roof systems) is placed above the roof membrane and below the stone.

To complete the roof system, a roof membrane with a historical in situ record of exposure performance and resistance to UV is needed. EPDM satisfies this requirement with its carbon black component, as well as its proven performance, given this author’s experience with EPDM roofs designed 30 years ago which are still in service today. Thermal insulation layers should be multiple, and in the range of 3 inches (7. 5 cm) each.

This roof assembly can be seen in Photo 4 and is detailed in Figures 1A and 1B. It typically includes the following:

· Ballast to shade the membrane from solar heat gain and prevent reflection back at the walls and mechanical equipment. The aim is to provide a mass to gather the solar energy and not allow it to dissipate to the building interior, rooftop equipment, and/or the atmosphere.

· Drainage mat to provide a ventilation layer.

· EPDM to provide resistance to heat and UV radiation, and to provide a break in potential heat flow.

· Thermal insulation to “keep the hot out, and keep the cold in.”

There are several goals to this system, including:

1. Shade the roof membrane and thus provide a cooling layer.

2. Provide protection from the deleterious effects of heat and UV radiation.

3. Provide a ventilation plan to dissipate heat.

4. Eliminate the reflection on rooftop equipment.

5. Reduce cooling loads.

6. Provide a rooftop environment that will allow for the downsizing of rooftop equipment, and thus increase efficiency and lower energy usage.

7. Achieve a sustainable long-term roof system.

A roof system of similar concept was recently installed at the Queen Alia International Airport in Amman, Jordan, in which metal roof panels were elevated off the roof deck to form a cavity to vent any possible heat build-up. (See Photo 4.)

Design Recommendations

The goal of architects/designers should be to design roof systems to achieve sustainable and resilient long-term service lives. Today’s society is asking that roof systems provide more than just protection from the exterior environment. For extreme climatic areas of the world, the standard of care required to be exercised by the design professional has increased. For dry and hot climates interior comfort is paramount, and the roof system can be designed to assist rooftop HVAC systems in regard to performance, energy conservation, and efficiency, as well as extending the roof system service life.

Many of the required roof system design parameters apply, but for hot climates there are several key design elements that should be given consideration. Following are the design considerations that will provide a greater opportunity for successful roof systems in hot and dry climates:

1. Ensure collaboration and coordination with the HVAC system designer. The association between potential heat flow, resultant interior heat gain and cooling demand is so closely related that it would appear obvious that the coordination of the two building system designers should be a given. Unfortunately, this is far from reality.

2. Gain an understanding that heat energy is first and foremost transmitted by solar energy, and protecting the roof membrane’s surface from the “sun’s rays” will result in diminished heat gains. Use indigenous concepts to your benefit.

3. Use thermal insulation to provide a formidable barrier between the interior and exterior environments. It is not only about the cost of cooling that should be dictating the amount of insulation, but the loss of cool air and preventing heating. This author feels that the insulation amounts used on roofs of hot climates should be equal to those in cold climates.

4. Shading 1: Protecting the roof surface from direct contact by the solar radiation will provide enormous benefits.

5. Shading 2: The shading element typically will absorb (to the extent the solar radiation is not deflected), thus minimizing and/or absolving the effects of heat flow to the interior.

6. Specify roof membranes (roof covers) that have a history of in situ long-term performance in hot climates.

7. Specify roof membranes (roof covers) that have high resistance to ultraviolet radiation.

8. Specify roof membranes (roof covers) that have high resistance to heat aging.

9. Understand that the high base flashings are part of the roof system and will need to be designed appropriately. The should be protected with double layers of flashings.

10. Specify robust and durable materials: Increase the thickness of roof membranes and covers. If the membrane is reinforced, the thickness of material protection above the scrim is the critical dimension.

11. Design roof system components with the same care for the effects of the sun, solar radiation, and heat as you would the roof. For example, the use of no-hub couplings on roof drains will see the sun for several hours each day and will deteriorate over time, and will become attributable to one of those “hidden, mystery” leaks.

12. Use the historically proven method of heat disbursement: Provide a ventilation layer above the roof membrane (roof cover).

13. Design to protect rooftop HVAC equipment and walls from deflected solar radiation. Remember how you started a fire as a kid with a magnifying glass? This is the same concept.

14. When using metal components such as roof edge copings, realize that the temperature of the metal during daylight periods will work to heat age and deteriorate the roofing below. Try to incorporate a ventilation layer below the metal.

The Importance of the Roof

The design of roof systems has historically been given little forethought, and was often regulated to junior designers with little or no empirical experience, and armed with little more than a “canned” master specification that provided little more than a market-driven minimum of a roof system. Today’s buildings are much too expensive and sophisticated to allow poorly conceived and designed roof systems to prevail. With an increase in detrimental “climactic events,” roof systems demand the same level of consideration and design as do all other building systems: structural, mechanical, plumbing, communications, and building envelopes.

Hot climates are special and unique climatic environments, and as such, have special environmental conditions that need to be designed for. Using empirical and historical information, proven materials, and designing to particular in situ environmental conditions can produce roof systems that will reach sustainable levels of performance. With proper coordination with HVAC designers, the roof can rise above just a protection layer, and provide both raised interior comfort and greater HVAC cooling efficiencies. Greater emphasis on education on proper, innovative, and sustainable roof system design can be achieved if all stakeholders (manufacturers, contractors, architects, engineers and consultants) work together.

It is well past the time to move roofing system design to the forefront of building design and have it become a system that is appreciated for its crucial role in energy conservation and resilient construction.

About the author: Thomas W. Hutchinson, AIA, CSI, Fellow-IIBEC, RRC, is a principal of Hutchinson Design Group Ltd. in Barrington, Illinois. For more information, visit www.hutchinsondesigngroup.com.

Regular Roof Inspections Help ‘Keep the Door Open’

A roof inspector makes field observations. Photo: Kemper System America Inc.

Regular roof inspections give consultants and contractors a chance to maintain relationships with building owners and managers and create value beyond any immediate repairs.

Commercial roofs should be inspected at least twice a year, typically in the spring and fall. Roof inspections are also advised after major weather events, though contractors may already be deluged with repair requests. Of course, building managers will be more receptive to discussing regular inspections during such times, even though time is short. A service flyer and readily available letter-of-agreement can help quickly close the deal, and be used after any major job throughout the year to create recurring business. Customers should clearly understand the service offer and any special provisions for emergency repairs or exceptions such as during wider emergencies.

Common Sources of Roof Leaks

  • Cracks in or around flashings and penetrations
  • Breaks in and around gutterways and drains
  • Poor drainage or debris-clogged drainage systems
  • Storm damage, tree branches, ice dams, etc.
  • Incidental damage by other trades during construction or maintenance
  • Excessive foot traffic at rooftop access points and around HVAC units and other rooftop infrastructure
  • Old or deteriorating roofing materials

While roof leaks can be caused in several ways, many common sources of leaks can be prevented with liquid-applied coating and membrane systems that fully adhere to substrates and are both self-terminating and self-flashing. Membrane systems are fully reinforced and create a seamless surface. High-quality systems are designed to withstand ponding water, ice, snow, UV light, as well as most chemicals. Unreinforced roof coatings can be used for repairs or complete restoration of the roof surface.

If only a small area is damaged, a limited repair is best, and usually possible with compatible materials over an existing system in good condition.Check if a warranty is in place, and if possible contact the manufacturer before the repair. Perform any repairs within the guidelines of the warranty.

For wider areas, a roof recovery is often possible right over the existing roofing. If interior leaks from a field area are evident, core samples can verify the condition of the existing roof assembly down to the deck. Built-up roofs (BUR), in particular, are susceptible to sun and temperature cycling. Tiny spider cracks and micropores can develop in the surface, and the layers below can absorb moisture and deteriorate. Water always travels to its lowest point and, if left unchecked, will damage the underlying structure.

On low-slope roofs, areas of ponding water are a prime target for inspections. If the roof is covered by aggregate or overburden, it must be cleared from around the lowest point of any low-lying areas, and other areas of suspected damage. A visual inspection can locate the source of an active leak, but there may be more than one source or a larger issue that may not always be visible. Broader sampling is needed to evaluate the general condition of the roof and the scope of any deterioration.

Quality workmanship and materials help avoid callbacks and ensure long-term relationships. After completing any necessary repairs, a PMMA, polyurethane or elastomeric membrane or coatings system can be installed to extend the service life of an existing roof. Elastomeric-based coatings are generally the best value for straightforward repairs and can be ideal for recovering metal roofs. Roof restoration, in general, can enhance building performance with “Cool Roof” products, especially those with a high solar reflectance index (SRI).

At the end of the day, an ounce of prevention and a prompt response to issues can help building owners avoid expensive headaches. People remember expert advice and quality service, especially in times of need. They also may tell others — which is another way regular inspections can help keep the door open to recurring business.

New Roof Provides Security at Senior Living Complex

Photo: Johns Mansville

The Preserve At Palm-Aire is a landmark senior living community in Pompano Beach situated on 13 acres of lush, beautiful grounds in South Florida. Offering both independent living and assisted living programs, the health care facility’s primary focus is on preserving residents’ quality of life in every way possible.

The independent senior lifestyle at The Preserve At Palm-Aire is all about maintenance-free living, and that philosophy influenced the choice of a new roofing system for the facility.

The re-roofing of The Preserve At Palm-Aire was complicated by Mansard-style roofs and 5-foot to 6-foot high parapet walls that greatly restricted access to the existing roofing system, which was installed on a lightweight structural concrete deck. The use of trash chutes was impossible, so a large crane and dumpster were used to remove the roofing debris.

“What concerned us most was using such a large crane around an immaculately landscaped property fully occupied by tenants especially sensitive to excess noise and vibration,” says Geo Madruga, commercial project coordinator for A-1 Property Services Inc., the Miami-based roofing contractor on the project. Another important concern was that the low-slope roof had numerous penetrations, including those for 30 large HVAC units and various pipes and stack vents.

Finding a Solution

A-1 Property Services Inc. competed with several other contractors on an open spec bid. With the help of JM Sales Representative Lewis Buckner, A-1 advised the property owner that a 60-mil fleece-backed PVC membrane with DuPont Elvaloy KEE would provide the longevity, energy efficiency and chemical resistance required for the project. “We really pushed the PVC fleece backed as the superior roofing system and a unique solution for this building,” says Madruga. “We also felt more comfortable with JM’s PVC membrane due to our long track record with the product.”

Adhered directly to the concrete deck with a water-based adhesive, the fleece-backed PVC exceeded Broward County’s 175-mph wind resistance requirement. The PVC membrane’s high reflectivity also earned an energy efficiency rebate from Florida Power & Light Company. The product was also easy to install, depite the numerous penetrations, notes Madruga. “While there were definitely many unique penetrations, our 10-man crew had no problems with the heat-weldable PVC membrane,” he says.

Madruga’s concerns — and his company’s name — both reflect A-1’s desire to create long-term relationships with clients that include expert maintenance services. “We met the expectations of the owner’s roof consultant, but with offices in Washington D.C., the client placed a tremendous amount of trust in the roofing manufacturer and contractor,” adds Madruga. “We are specialists, and we don’t just walk away from any roofs that we install.”

TEAM

Building Representative: CRP Preserve Palm-Aire LLC, Washington, D.C.
Roofing Contractor: A-1 Property Services Inc., Miami, Florida

MATERIALS

Roofing System: 60-mil Fully Adhered Fleece-Backed PVC, Johns Manville, www.JM.com

GreenSlope’s New and Improved Formula Provides an Environmentally Friendly Solution to Ponding Water

GreenSlope is a roof leveling compound that helps eliminate ponding water on flat rooftops by filling in low areas, returning the roof to its original slope to achieve positive water flow to desired drainage areas. Following advanced in-house innovation and successful market testing, GreenSlope has been re-engineered for 2018 and now ships with a new and improved formula.

GreenSlope’s new formula features an improved adhesive, dramatically shortening the curation period from 24 hours to 2 hours, which allows for same-day topcoating. GreenSlope has also upgraded to finer-grade EPDM granules, which are less porous, easier to work with, and offer superior UV resistance and longevity. GreenSlope’s robust adhesive forms an exceptional bond with a wide variety of roof systems including single-ply, modified bitumen/BUR, metal and foam roof systems. The cured material is similar to a professional running track or premium playground surface, able to withstand extreme climates and as well as foot traffic.

At 20 percent the weight of concrete alternatives and half the weight of ponding water, GreenSlope reduces stress on the roof system by facilitating proper water drainage to extend the lifespan of the roof at a fraction of the time and cost it takes to install a new drain or tapered insulation. GreenSlope’s UV-stable compound can endure frequent freeze/thaw cycles and resists wear and tear while remaining flexible to absorb surface stresses. Highly malleable, GreenSlope can be used in a wide variety of practical scenarios including around low drains and scuppers, as walk pads and pitch-pan filler, for protection around curbs, HVAC units and more.

The product can be easily applied over low areas using a trowel and straightedge to smooth and level. For best results, additional topcoat application is recommended to achieve reliable waterproofing and match the aesthetics of the existing roof. GreenSlope is compatible with most topcoats including white acrylic, aluminum mastic, modified mastic, elastomerics, emulsions, and membranes.

The problem of ponding water offers service divisions an opportunity to open new doors with prospective clients. Ponding water can be found on eight out of 10 flat roofs and is one of the most commonly reported concerns of contractors and building owners as it can cause leaks, structural damage, membrane damage, algae and mold growth, slip hazards, insect problems, voided warranties, and premature failure of roof systems. Conventional options to deal with ponding include installing a new inner drain or adding tapered insulation, but these options are often expensive for building owners and not always necessary. GreenSlope’s preventative approach helps building owners maintain their roof asset while maximizing rooftop ROI. Additionally, going green offers potential LEED credits.

GreenSlope is manufactured and distributed by United Asphalt.

LEARN MORE

Visit: https://greenslope.co/
Call: (877) 356-9301
Email: team@greenslope.net

The “Roofers’ Choice” winner is determined by the product that receives the most reader inquiries from the “Materials & Gadgets” section in a previous issue. This product received the most inquiries from our September/October 2017 issue.

Efficient and Effective Construction Through Building Codes

This fire station roof assembly includes thermally efficient cross-ventilated non-structural composite insulation manufactured by Atlas Roofing and installed by Utah Tile & Roofing.   Photos: Atlas Roofing Corp

This fire station roof assembly includes thermally efficient cross-ventilated non-structural composite insulation manufactured by Atlas Roofing and installed by Utah Tile & Roofing. Photos: Atlas Roofing Corp

In a world where the bottom line is a critical concern in any construction project, conscientious design and roofing professionals look at the lifetime costs of a building instead of just the short-term construction outlay. Choices made during a building’s initial design and construction have long-term influence on the lifetime of its operation and maintenance. With so many building products and options available, building codes take on a vital role in guiding decisions about building quality, safety, and energy performance. These trusted benchmarks, compiled with input from a broad range of stakeholders, are designed to ensure that the best technologies, materials, and methods are used in construction.

Building Energy Codes 101

Model building energy codes are revised every three years to incorporate the latest research and ensure that new and existing buildings benefit from the methods and products that will produce the most value and safety over time. The International Energy Conservation Code (IECC) and ASHRAE set standards tailored to specific climate zones and include options to provide flexibility in choosing the methods and materials best suited to each project’s needs while nevertheless meeting the requirements. Without regular, incremental improvements to these codes, new buildings would be dated even before their construction begins.

Indeed, while some building features are straightforward to replace and upgrade over time, some of the most vital elements of building performance need to be “designed in” at the outset. Codes are designed to lock in savings during initial construction or major renovations to promote cost-effective design and construction practices. For example, roof replacement projects provide an opportunity to cost-effectively improve the overall energy efficiency performance of buildings.

Energy-efficient design strategies are helpful to all building owners, including government and municipal projects built with taxpayer funding. Pictured here is Fire Station #108 in Brighton, Utah. Photos: Atlas Roofing Corp.

One of the major benefits of building code updates in recent years is the focus on energy efficiency and resiliency. The Insurance Institute for Business and Home Safety writes that, “Over the centuries, building codes have evolved from regulations stemming from tragic experiences to standards designed to prevent them.” With the ongoing effects of climate change, buildings are subjected to extremes of weather and temperature that challenge the performance of their systems. Most structures built over the previous century were not designed or constructed with energy efficiency in mind and suffer from poor insulation and dramatic thermal loss. Buildings account for over 40 percent of America’s total energy consumption, 74 percent of our electricity, and cause 40 percent of our greenhouse emissions. Implementing best practices for sustainable design and utilizing highly efficient building materials like insulation could save billions of dollars a year and improve the reliability of the electrical grid systems.

Energy-Efficient Roofing

A report prepared in 2009 by Bayer MaterialScience (now Covestro), “Energy and Environmental Impact Reduction Opportunities for Existing Buildings with Low-Slope Roofs,” determined that going from an R-12 insulation level (i.e., the average R-value of roofs on older buildings) to R-30 would pay for itself in energy savings in just 12 years with an average reduction in building energy use of 7 percent. Better roof insulation also saves money on equipment, since buildings with weaker envelopes require larger and costlier HVAC systems and future upgrades to HVAC equipment that is smaller and less expensive will always be limited by this constraint.

These savings are not only confined to new construction. In renovations, the removal and replacement of a roof membrane offers the best and most cost-effective opportunity to improve a building’s thermal envelope and better position that building for energy-efficiency upgrades down the road.

Energy Efficiency in Government Buildings

While these strategies are helpful to all building owners, they are especially important for government projects built with an increasingly tight supply of taxpayer dollars. Here is another place where the building codes provide a major assist. For federal commercial and multi-family high-rise residential buildings where the design process began after Nov. 6, 2016, agencies are required to design buildings to meet ASHRAE 90.1-2013 and, if life-cycle cost-effective, achieve energy consumption levels that are at least 30 percent below the levels of the ASHRAE 90.1-2013 baseline building. These savings are calculated by looking at the building envelope and energy consuming systems normally specified by ASHRAE 90.1 (such as space heating, space cooling, ventilation, service water heating, and lighting but not receptacle and process loads not covered by 90.1).

Photos: Atlas Roofing Corp.

Changes in the 2013 edition of ASHRAE 90.1 clarify the insulation requirements of various low-slope re-roofing activities. New definitions of “roof covering” (the topmost component of the roof assembly intended for weather resistance, fire classification, or appearance) and “roof recovering” (the process of installing an additional roof covering over an existing roof covering without removing the existing roof covering) were added and the exceptions to the R-value requirement for roof replacements were clarified to include only “roof recovering” and the “removal and replacement of a roof covering where there is existing insulation integral to or below the roof deck.” In all other instances, when a roof membrane is removed and replaced, the insulation must be brought up to current R-value requirements, which range from R-20 to R-35, depending on climate zone. In addition, the prescriptive R-value requirements for low-slope roofs under 90.1-2013, as compared to previous version (90.1-2010), are higher. For instance, in populous climate zones 4 and 5 the R-values for these roofs increased from R-20 to R-30.

The Department of Energy is preparing to start a rulemaking process to update the federal building energy standard baseline to the 90.1-2016 Standard, which will provide about an 8 percent improvement in energy cost savings compared to 90.1-2013. However, no changes were made to the R-values for low-slope roofs. Managers of federal buildings are working to comply with updated directives that impact new construction and building alterations, including:

  • “Guiding Principles for Federal Leadership in High Performance and Sustainable Buildings”
  • GSA PBS-P100 “Facilities Standards for the Public Buildings Service”
  • DOD’s Unified Facilities Criteria (UFC).

The instructions in these publications coupled with Executive Order 13693, issued on March 15, 2015, and “Guiding Principles for Sustainable Federal Buildings,” require new and existing federal buildings to adopt improved energy efficiency and “green building” attributes. New buildings are expected to “employ strategies that minimize energy usage” and existing ones must “seek to achieve optimal energy efficiency.” These directives require:

  • Regular benchmarking and reporting of building annual energy use intensity.
  • Annual 2.5 percent improvement in energy use intensity every year through the end of 2015.
  • All new buildings be designed to achieve net-zero energy use beginning in 2020.

Good Practice in Action

At the end of the day, the success of building codes in producing the cost-savings, weather-resiliency, and energy efficiency is determined by how they are adopted and enforced locally. If the most current codes were universally adopted and enforced,

Photos: Atlas Roofing Corp.

there would be no competitive advantage to inferior building construction practices. Incremental upgrades would provide a steady stream of work that would increase competitiveness for building professionals and suppliers. Updated job skills would increase market value for construction professionals and enable innovation in the construction sector and increased market share for innovative products and processes that would improve economies of scale and lower their cost differential.

Building codes provide a comprehensive and reliable standard that contribute to local economies and improve building performance. Knowledge of code requirements help designers and contractors deliver more value to their clients. Finally, a bit more of an investment during design and construction can yield significant savings in building operation and tangible benefits to the environment and economy of areas that adopt higher building standards.

Re-Roofing of Shopping Center Poses Logistical Challenges

Southgate Shopping Center: Sebring, Florida

The re-roofing project of the shopping center totaled 79,556 square feet.

The re-roofing project of the shopping center totaled 79,556 square feet.

Roofing contractors often find themselves tackling re-roofs at shopping centers in piece-meal fashion, doing sections over the years as the budget allows. When property manager Southern Management and Development decided to remodel the entire Southgate Shopping Center in Sebring, Fla., in conjunction with Publix Markets’ replacement of their existing store at the location, they looked to Advanced Roofing to get the job done.

The scope of work included re-roofing three large sections of the retail plaza and a drugstore on the property. The roofing portions totaled 79,556 square feet.

Roof System

The roof specified was a two-ply modified bitumen system from Johns Manville. In the three large sections of the plaza, the existing built-up roof was completely torn off, while the drugstore was a re-cover project, notes Andrew Vik, estimator and project manager with Advanced Roofing’s Tampa branch, which operates under branch manager Michael Landolfi.

Roofing work started in November 2016 and was completed in February 2017. After the existing roof was removed, crews installed 2-inch polyiso to the steel deck. “We mechanically fastened that with a half-inch USG SecuRock cover board through the steel deck,” notes Vik. “The two plies of modified bitumen were then torch applied, a smooth base sheet and a white granulated cap sheet.”

On the drugstore, the roof was vacuumed, and the cover board and two plies were installed over the top of the old roof system.

In addition to the roofing scope, Advanced Roofing’s HVAC division installed and removed heating and air conditioning units and replaced some obstructive ductwork. “We had our own HVAC people working with our roofing crews, so it was easy to coordinate everything,” notes Vik. “We had HVAC installations on three of the buildings, and we remounted existing units on two of the buildings. There was also a lot of demolition on the south building, as there were several derelict units that
had been sitting there for quite some time. Those had to be hoisted off there and taken out.”

A Challenging Project

In addition to the roofing scope, Advanced Roofing’s HVAC division installed and removed heating and air conditioning units and replaced some obstructive ductwork.

In addition to the roofing scope, Advanced Roofing’s HVAC division installed and removed heating and air conditioning units and replaced some obstructive ductwork.


Logistics are often a challenge with a shopping center that remains open to the public, notes Vik. “You have to load and unload multiple levels of the roof at different times,” he says. “Customer relations is also a challenge; you have to keep everyone happy and ask a lot of questions. The construction manager has to do a lot of P.R. when he’s there.”

Demolition portions of the project were done at night and application during the day, so business at the mall was never disrupted. Traffic in the parking area was also a key concern.

“Setup areas had to be barricaded and marked off while we were loading and unloading,” Vik says. “There was even a drive under bridge connecting two buildings that had to be re-roofed, so we always had to be mindful of people below.”

Parapet walls did not surround all portions of the roof, so safety precautions included a safety perimeter; employees outside the perimeter had to be harnessed and tied off to a portable fall protection anchor system by Raptor.

The project went off without a hitch, according to Vik. “The mall was 100 percent open during the entire project,” he says. “Things went very smoothly— especially for everything that was involved. One of our mottoes is, ‘The harder the job, the better.’ We like a challenge. We take on a lot of projects other companies shy away from.”

The keys to his company’s success are coordination and versatility, states Vik. “We do it all,” he says. “We didn’t have to get anybody from outside the company to work on the project. We did all the roofing, all of the HVAC, and all of the hoisting was done in-house. We’ve also got lightning protection inhouse, and we have a solar division. We have a great team. Everyone does their part to get the bids out and get the jobs done. It’s the best team I’ve ever worked with.”

Team

Roofing Contractor: Advanced Roofing Inc., Tampa, Fla.
Consultant: CBA Roof Consulting LLC, Lake Worth, Fla.
Roof System Manufacturer and Technical Support: Johns Manville, Denver

Vivint Solar Inc. and Renovate America Collaborate to Offer Rooftop Solar to More Homeowners

Vivint Solar Inc. and Renovate America are collaborating to expand access to rooftop solar for homeowners. By offering Renovate America’s HERO program as its PACE financing option, Vivint Solar is enabling more homeowners to purchase solar systems and lower their utility bills.

Under this business agreement, homeowners will be able to use HERO financing to purchase Vivint Solar systems and pay for them over time through their local property taxes. Payments are made at a fixed interest rate for terms of five to 20 years, and the interest on the payments may be tax deductible. Since it is expected that the system will stay with the home and provide utility savings into the future, any remaining balance on the assessment may be able to transfer to a new homeowner at the time of sale.

The announcement of this relationship comes at the same time as the Federal Housing Administration’s recently issued federal policy guidance that endorses PACE financing.

“We are excited to work together with Renovate America to provide this solar financing product that will make solar available to a range of consumers, including those who either do not have the upfront capital for a solar energy system or for whom traditional loans, Power Purchase Agreements or Solar System Lease Agreements are not viable options,” said Vivint Solar Executive Vice President of Capital Markets, Thomas Plagemann. “We are pleased with the new FHA guidelines that open the door to wider acceptance of the PACE financing product throughout the United States.”

Since its launch at the end of 2011, HERO, which stands for Home Energy Renovation Opportunity, has financed more than $1.5 billion of improvements such as solar, energy-saving roofing, windows, and doors, more efficient HVAC systems, and building insulation. About a quarter of the home energy improvement projects – around 19,000 – have been rooftop solar installations.

“More than 67,000 homeowners have invested in the efficiency of their homes,” said Greg Memo, executive vice president of business development and product strategy at Renovate America. “Vivint Solar and Renovate America are able to provide more families the ability to go solar and lower their utility bills.”

Vivint Solar is rolling out the HERO Program throughout California, and both companies are working with state and local governments to expand this product offering nationwide.

Roofinox Displays Its Line of Stainless Steel Roofing Products to Contractors and Architects

Roofinox displays its line of stainless steel roofing products to contractors and architects attending the Moon in June Machinery Show in Lynchburg, Va. The annual exposition is specifically developed to showcase the latest advancements in roofing machinery and materials by N.B. Handy Company, HVAC equipment and supplies.

“We appreciate Roofinox’s participation in this year’s event,” says Paul Seufer, general manager of the N.B. Handy Machinery Group. “Our goal is to spotlight sheet metal fabrication machinery and materials available in the marketplace. This includes the interactive display of services in an environment where customers can experience processes and benefits first-hand. Roofinox’s stainless steel roofing products offer forming characteristics that run through our equipment.”

“It is a privilege to work alongside N.B. Handy,” says Dave Rowe, vice president at Roofinox America. “This event provides a wonderful opportunity for building professionals to interact with experts, ask questions and actually witness how our products work with their equipment under in-field conditions.”

Roofinox provides a range of tin-plated (Terne) products designed to offer sustainability and corrosion-resistance for wall-cladding, flashing, rainware, interior design and virtually all forms of roofing applications. Roofinox Tin-plated (Terne) is specifically developed and manufactured for roll forming and fabricating.

Developed to withstand climatic conditions found in Central Europe, the Roofinox Stainless Steel product line is ideal for applications ranging from rural, urban and light industrial areas to historic and commercial sites and coastal environments. With ongoing exposure to the elements, Roofinox Tin-plated (Terne’s) surface will develop an elegant matt grey patina finish over time.

A substitute for lead-coated copper, zinc/tin-zinc coated copper, Terne-coated materials, galvalume and lead, Roofinox Tin-plated (Terne) is available in coil or sheet. Materials can be ordered by themselves so customers can do their own forming or prefabricated by a Roofinox distributor.

Adapt Existing Roof Curb to New Rooftop Unit

A Thybar Multi-Zone Retro-Mate is custom made to adapt your existing roof curb to a new rooftop unit.

A Thybar Multi-Zone Retro-Mate is custom made to adapt your existing roof curb to a new rooftop unit.

A Thybar Multi-Zone Retro-Mate is custom made to adapt your existing roof curb to a new rooftop unit. It saves time and costly roof reconstruction, preserves roofing integrity, reduces system downtime, and takes advantage of existing multi-zone ductwork. Convert a single-zone constant or variable-volume rooftop unit into a variable-volume multi-zone. Our comprehensive library of new and old rooftop specifications lets us design a matching Retro-Mate without extensive field measurements. Reduced engineering and construction time lets you bid more competitively. Licensed P.E. on staff.

Adapt Existing Roof Curb to a New Rooftop Unit

A Thybar Retro-Mate is custom made to adapt the existing roof curb to a new rooftop unit.

A Thybar Retro-Mate is custom made to adapt the existing roof curb to a new rooftop unit.

A Thybar Retro-Mate is custom made to adapt the existing roof curb to a new rooftop unit. It saves time and costly roof reconstruction, preserves roofing integrity, reduces system downtime, and takes advantage of existing ductwork. The comprehensive library of new and old rooftop specifications allows for the design of a matching Retro-Mate without extensive field measurements.