NIBS States Proposed ABA Resolution to Make Codes and Standards Free Could Reduce Safety

The National Institute of Building Sciences issued an open letter to delegates attending the American Bar Association (ABA) Annual Meeting in August informing of the potential impacts if they vote to support a proposed resolution. The resolution—which advocates that copyrighted codes and standards incorporated by reference in legislation and regulation be made available for free—would alter the way codes and standards are developed in the United States.

In the U.S. construction industry alone, there are hundreds of copyrighted codes and standards that impact everything from seismic requirements and wind loads to water use and life safety. The standards developing organizations (SDOs) that develop these codes and standards have thousands of members, employees and volunteers that participate in the process to incorporate best practices and lessons learned to improve the standards. Each industry, from aeronautics and agricultural to electronics and telecommunications, has a similar structure and industry participation to address their specific needs. Such standards improve safety, drive innovation and improve commerce, both domestically and around the world.

The U.S. Government recognizes the benefit of private industry standards development, as directed by the National Technology Transfer and Advancement Act (NTTAA, P.L. 104-113) and Office of Management and Budget (OMB) Circular A-119.

If the ABA’s suggested resolution and related advocacy campaign is successful, private-sector-developed standards would be subject to new requirements due to their incorporation by reference in legislation and regulation, and the ability for SDOs to recoup development costs would change considerably.

The development of codes and standards is expensive. Today, the cost is born by those who are ultimately impacted by the standards (whether by participating in the process or purchasing the resulting document). By making such information free online, the ABA resolution would hamper cost recovery through such mechanisms. The result would be that private-sector organizations may no longer be able to invest in the development process, leaving existing standards to remain stagnant (and thus inhibiting innovation) and shifting the responsibility (and expense) of developing future standards to the government.

ABA’s proposed resolution attempts to mitigate any copyright concerns by encouraging government agencies to negotiate licenses with SDOs. However, this change would require agencies to hire staff and implement contracting mechanisms, making it necessary for tax payers to cover the cost of standards development.

The National Institute of Building Sciences—which was established by the U.S. Congress to work with both the public and private sectors to advance building science and the design, construction and operations of buildings to meet national goals of health, safety and welfare—is extremely concerned that the ABA is advocating a one-size-fits-all legislative vehicle that will alter the long-standing tradition of private-sector-developed standards in the United States. The result could reduce safety, increase costs and add a burden to the government and tax-paying citizens.

In lieu of moving forward with the resolution, the Institute suggests the ABA focus on engaging in a meaningful dialogue with the SDO community to help address the changing nature of access to copyrighted materials through the internet and other electronic sources, and, after taking the long-term goals and impacts into consideration, identify a mutually acceptable path forward.

Read the letter.

The Building Industry Is Working to Reduce Long-term Costs and Limit Disruptions of Extreme Events

“Resilience is the ability to prepare for and adapt to changing conditions and to withstand and recover rapidly from deliberate attacks, accidents, or naturally occurring threats or incidents.” —White House Presidential Policy Directive on Critical Infrastructure Security and Resilience

In August 2005, Hurricane Katrina made landfall in the Gulf Coast as a category 3 storm. Insured losses topped $41 billion, the costliest U.S. catastrophe in the history of the industry. Studies following the storm indicated that lax enforcement of building codes had significantly increased the number and severity of claims and structural losses. Researchers at Louisiana State University, Baton Rouge, found that if stronger building codes had been in place, wind damages from Hurricane Katrina would have been reduced by a staggering 80 percent. With one storm, resiliency went from a post-event adjective to a global movement calling for better preparation, response and recovery—not if but when the next major disaster strikes.

CHALLENGES OF AN AGING INFRASTRUCTURE

We can all agree that the U.S. building stock and infrastructure are old and woefully unprepared for climatic events, which will occur in the years ahead. Moving forward, engineering has to be more focused on risk management; historical weather patterns don’t matter because the past is no longer a reliable map for future building-code requirements. On community-wide and building-specific levels, conscientious groups are creating plans to deal with robust weather, climatic events and national security threats through changing codes and standards to improve their capacity to withstand, absorb and recover from stress.

Improvements to infrastructure resiliency, whether they are called risk-management strategies, extreme-weather preparedness or climate-change adaptation, can help a region bounce back quickly from the next storm at considerably less cost. Two years ago, leading groups in America’s design and construction industry issued an Industry Statement on Resiliency, which stated: “We recognize that natural and manmade hazards pose an increasing threat to the safety of the public and the vitality of our nation. Aging infrastructure and disasters result in unacceptable losses of life and property, straining our nation’s ability to respond in a timely and efficient manner. We further recognize that contemporary planning, building materials, and design, construction and operational techniques can make our communities more resilient to these threats.”

With these principles in mind, there has been a coordinated effort to revolutionize building standards to respond to higher demands.

STRENGTHENING BUILDING STANDARDS

Resiliency begins with ensuring that buildings are constructed and renovated in accordance with modern building codes and designed to evolve with change in the built and natural environment. In addition to protecting the lives of occupants, buildings that are designed for resilience can rapidly re-cover from a disruptive event, allowing continuity of operations that can liter- ally save lives.

Disasters are expensive to respond to, but much of the destruction can be prevented with cost-effective mitigation features and advanced planning. A 2005 study funded by the Washington, D.C.-based Federal Emergency Management Agency and conducted by the Washington-based National Institute of Building Sciences’ Multi-hazard Mitigation Council found that every dollar spent on mitigation would save $4 in losses. Improved building-code requirements during the past decade have been the single, unifying force in driving high-performing and more resilient building envelopes, especially in states that have taken the initiative to extend these requirements to existing buildings.

MITIGATION IS COST-EFFECTIVE IN THE LONG TERM

In California, there is an oft-repeated saying that “earthquakes don’t kill people, buildings do.” Second only to Alaska in frequency of earthquakes and with a much higher population density, California has made seismic-code upgrades a priority, even in the face of financial constraints. Last year, Los Angeles passed an ambitious bill requiring 15,000 buildings and homes to be retrofitted to meet modern codes. Without the changes, a major earth- quake could seriously damage the city’s economic viability: Large swaths of housing could be destroyed, commercial areas could become uninhabitable and the city would face an uphill battle to regain its economic footing. As L.A. City Councilman Gil Cedillo said, “Why are we waiting for an earthquake and then committed to spending billions of dollars, when we can spend millions of dollars before the earthquake, avoid the trauma, avoid the loss of afford- able housing and do so in a preemptive manner that costs us less?”

This preemptive strategy has been adopted in response to other threats, as well. In the aftermath of Hurricane Sandy, Princeton University, Princeton, N.J., emerged as a national example of electrical resilience with its microgrid, an efficient on-campus power-generation and -delivery network that draws electricity from a gas-turbine generator and solar-panel field. When the New Jersey utility grid went down in the storm, police, firefighters, paramedics and other emergency-services workers used Princeton University as a staging ground and charging station for phones and equipment. It also served as a haven for local residents whose homes lost power. Even absent a major storm, the system provides cost efficiency, reduced environmental impact and the opportunity to use renewable energy, making the initial investment a smart one.

ROOFING STANDARDS ADAPT TO MEET DEMANDS

Many of today’s sustainable roofing standards were developed in response to severe weather events. Wind-design standards across the U.S. were bolstered after Hurricane Andrew in 1992 with minimum design wind speeds rising by 30-plus mph. Coastal jurisdictions, such as Miami-Dade County, went even further with the development of wind- borne debris standards and enhanced uplift design testing. Severe heat waves and brown-outs, such as the Chicago Heat Wave of 1995, prompted that city to require cool roofs on the city’s buildings.

Hurricane Sandy fostered innovation by demonstrating that when buildings are isolated from the supply of fresh water and electricity, roofs could serve an important role in keeping building occupants safe and secure. Locating power and water sources on rooftops would have maintained emergency lighting and water supplies when storm surges threatened systems located in basement utility areas. Thermally efficient roofs could have helped keep buildings more habitable until heating and cooling plants were put back into service.

In response to these changes, there are many opportunities for industry growth and adaptation. Roof designs must continue to evolve to accommodate the increasing presence of solar panels, small wind turbines and electrical equipment moved from basements, in addition to increasing snow and water loads on top of buildings. Potential energy disruptions demand greater insulation and window performance to create a habitable interior environment in the critical early hours and days after a climate event. Roofing product manufacturers will work more closely with the contractor community to ensure that roofing installation practices maximize product performance and that products are tested appropriately for in-situ behavior.

AVERTING FUTURE DISASTERS THROUGH PROACTIVE DESIGN

Rather than trying to do the minimum possible to meet requirements, building practitioners are “thinking beyond the code” to design structures built not just to withstand but to thrive in extreme circumstances. The Tampa, Fla.-based Insurance Institute for Business & Home Safety has developed an enhanced set of engineering and building standards called FORTIFIED Home, which are designed to help strengthen new and existing homes through system-specific building upgrades to reduce damage from specific natural hazards. Research on roofing materials is ongoing to find systems rigorous enough to withstand hail, UV radiation, temperature fluctuations and wind uplift. New techniques to improve roof installation quality and performance will require more training for roofing contractors and more engagement by manufacturers on the installation of their products to optimize value.

Confronted with growing exposure to disruptive events, the building industry is working cooperatively to meet the challenge of designing solutions that provide superior performance in changing circumstances to reduce long-term costs and limit disruptions. Achieving such integration requires active collaboration among building team members to improve the design process and incorporate new materials and technologies, resulting in high-performing structures that are durable, cost- and resource-efficient, and resilient so when the next disruptive event hits, our buildings and occupants will be ready.

Self-flashing Skylights on Commercial Warehouses Are Beginning to Leak

Today, many commercial roofers are dealing with a large-scale problem—reinstalling and replacing leaky self-flashing skylights on commercial warehouses. I have seen firsthand how improper installation of self-flashing skylights has become a headache for commercial property owners.

many of the skylights installed on commercial warehouse properties in the western Sunbelt states were installed improperly because they were installed first and foremost as fall protection for the open floor in the roof during construction by the builder and not by the roofer.

Many of the self-flashing skylights installed on commercial warehouse properties in the western Sunbelt states were installed improperly because they were installed first and foremost as fall protection for the open floor in the roof during construction by the builder and not by the roofer.

Around the late 1970s and early 1980s, intermodal freight became a huge part of global distribution. To handle the increase in freight projects, warehouse construction exploded. The Port of Oakland, for instance, invested heavily in intermodal container transfer capabilities in the ’80s. In fact, the aggressive growth of intermodal freight distribution continued into the early 2000s.

The cheapest and easiest way for skylights to be installed on these warehouses was to use self-flashing skylights. The metal curb or L bracket attached to the bottom of the skylight was, in theory, supposed to be set on top of the built-up roofing material and then stripped in, sandwiching the flange between he roofing layers. The result would be roofing material, then skylight, then more roofing material over the flashing on the skylight.

Unfortunately, many of the skylights installed on commercial warehouse properties in the western Sunbelt states were installed improperly because they were installed first and foremost as fall protection for the open floor in the roof during construction by the builder and not by the roofer. Our teams have seen thousands of these original self-flashing skylight installations where self-flashing flanges are set directly on the plywood roof deck, below all the roofing materials.

Most of the original roofers didn’t budget in the time and money it took to pull the skylight assembly apart from the roof deck and re-install it the proper way. Nor did they wash the oils off the new metal from the galvanizing process or use asphalt primer to prep the steel flanges of the assembly and ensure the roofing asphalt would stick properly. Over the years, as the metal of the skylight flanges expanded and contracted and the built-up roof did the same, but at a different rate, the roofing system eventually separated from the skylight, leaving a self-flashing skylight that’s now turned into what we jokingly refer to as a “self-leaking skylight”. This is part of the reason why everyone thinks skylights always leak.

The best way we’ve found to install leak-free skylights on a commercial warehouse roof, especially when re- placing the self-flashing skylights on an existing building, is to use a curb-mounted skylight. A curb-mounted skylight fits like a shoebox lid over a new curb the roofing contractor fabricates as part of the installation. This curbed design eliminates the metal flange and offers waterproofing redundancy in critical areas of the installation, so water can’t get into the building at the skylight opening. Because the new skylight is installed on a curb, it’s also much easier to address any future issues with the skylight or to replace it down the road if necessary. This especially comes in handy when owners lease to new tenants. New building occupancy regulations mean skylights may be required by municipalities to be changed out for smoke vents to comply with fire codes.

If you’re dealing with one or more self-flashing skylight leaks, there are a few things to keep in mind:

  • Check if there is condensation on the inside of the skylight; a lot of skylights have a trough where condensation runoff will leak into the building.
  • Be sure to check the juncture where the skylight and the roof meet (the skylight base flashing), which can sometimes include up to 5 inches of mastic at the base flashing.
  • If the skylight has a frameless acrylic cap without a metal frame around the outside, check the acrylic dome for stress cracks. It is possible to replace some acrylic domes on some skylights but often the cost of an acrylic dome is roughly the same as the cost of a new skylight, and if you’re already considering installing a new roof with a 15- to 20-year warranty, it doesn’t make much sense to leave the “self-leaking skylight” frame in place. Replacing the skylights during the reroofing project is much more cost-effective than re- turning to replace skylights later. In addition, skylight technology is far better now than it was 15 or 20 years ago (think about today’s impact-resistant polycarbonate and better UV and fall protection).

Above all else, don’t let self-flashing skylights give you and your roofing business a bad name. Instead, address the issue with your commercial clients and educate them about the best choices for their skylights and how they can stay current with the International Building Code and municipal codes. You’ll be helping them protect one of their biggest assets by ensuring their skylights stay leak-free.

PHOTOS: Highland Commercial Roofing

The Roofing Industry Seeks to Protect Buildings from Storms

I used to love storms. I was never one to cower at the sound of thunder. I often found storms a good excuse to turn off the TV and lights, open the blinds and marvel at the sheer power of nature. If you read my January/February “Raise the Roof”, however, you know I have had a love-hate relationship with rain since moving in with my husband (we married in August 2015). I found myself awake on rainy nights, counting the seconds between pumps of our sump
pump. If less than 20 seconds passed, I knew the basement was flooding and dreaded the morning’s cleanup. (I work from home and my office is in the basement.)

In March, a waterproofing company spent two days installing its patented drain- age system and a new sump pump inside our basement. We monitored the system throughout the month of April, which was rainy, to ensure there were no leaks in the system. It worked like a charm! During April, we also hired contractors to create my new home office, a guestroom and walk-in closet within the basement. So far, we have new windows, lighting and insulation; the contractors are finishing up drywall and ceiling installation as I type.

I know what it’s like when you can’t trust your house to weather a storm. There’s nothing worse than feeling powerless, and seeing your belongings destroyed is gut-wrenching. As the nation braces against another summer of intense weather, it’s comforting to know the construction industry—specifically roofing—is researching and innovating to protect people’s homes and businesses from Mother Nature’s wrath.

For example, in “Business Sense”, Jared O. Blum, president of the Washington, D.C.-based Polyisocyanurate Insulation Manufacturers Association, writes about initiatives to improve the resiliency of our building stock and infrastructure through codes, standards and proactive design.

The Clinton, Ohio-based Roofing Industry Committee on Weather Issues Inc., better known as RICOWI, recently sent 30 researchers to the Dallas/Fort Worth metroplex after an April hailstorm. According to Joan Cook, RICOWI’s executive director, the 10 teams of three inspected 3 million square feet of low and steep-slope roofing during the investigation. The teams’ findings will result in a report to help the industry better understand what causes roofs to perform or fail in severe hail events, leading to overall improvements in roof system durability. Learn how RICOWI mobilizes and studies roofs in “Special Report”.

There are many other stories within this issue about roof systems working along- side other building components to create durable, sustainable and energy-efficient buildings. Humans have a long history of innovating and evolving to meet the needs of their current situation. I have no doubt that in my lifetime our buildings will be built to withstand nearly any catastrophic event. Meanwhile, I’m happy to report we received 4 1/2 inches of rain in three hours last week and our basement remained bone dry. Thanks to innovations in basement waterproofing, I may start to enjoy storms just a bit again!

Attic Ventilation in Accessory Structures

Construction Code Requirements for Proper Attic Ventilation Should Not Be Overlooked in Buildings That Don’t Contain Conditioned Space

The 2015 International Residential Code and International Building Code, published by the International Code Council, include requirements for attic ventilation to help manage temperature and moisture that could accumulate in attic spaces. Although the code requirements are understood to apply to habitable buildings, not everyone understands how the code addresses accessory structures, like workshops, storage buildings, detached garages and other buildings. What’s the answer? The code treats all attic spaces the same, whether the space below the attic is conditioned or not. (A conditioned space is a space that is heated and/or cooled.)

The 2015 International Residential Code and International Building Code include requirements for attic ventilation to help manage temperature and moisture that could accumulate in attic spaces. Although the code requirements are understood to apply to habitable buildings, not everyone understands the code also addresses accessory structures, like workshops, storage buildings, detached garages and other buildings.

The 2015 International Residential Code and International Building Code include requirements for attic ventilation to help manage temperature and moisture that could accumulate in attic spaces. Although the code requirements are understood to apply to habitable buildings, not everyone understands the code also addresses accessory structures, like workshops, storage buildings, detached garages and other buildings.


The administrative provisions of the IRC that set the scope for the code are found in Chapter 1. Section R101.2 and read:

    The provisions of the International Residential Code for One- and Two-family Dwellings shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one- and two-family dwellings and townhouses not more than three stories above grade plane in height with a separate means of egress and their accessory structures not more than three stories above grade plane in height.

Let’s clear up any confusion about the code. The ventilated attic requirements in the 2015 IRC include the following language in Section R806.1:

    Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.

An accessory structure is actually defined in the IRC:

    ACCESSORY STRUCTURE. A structure that is accessory to and incidental to that of the dwelling(s) and that is located on the same lot.

The IBC also includes attic ventilation requirements that are essentially the same as the IRC. Section 101.2 of the 2015 IBC contains this text:

    The provisions of this code shall apply to the construction, alteration, relocation, enlargement, replacement, repair, equipment, use and occupancy, location, maintenance, removal and demolition of every building or structure or any appurtenances connected or attached to such buildings or structures.

This requirement for ventilated at-tics in accessory structures in the IBC and IRC is mandatory unless the attic is part of the conditioned space and is sealed within the building envelope. Unvented, or sealed, attics allow any ducts located in the attic to be inside the conditioned space, which can have beneficial effects on energy efficiency. For accessory structures, which are typically unheated, that provision does not apply.

It’s important to note the codes do contain detailed requirements for the design and construction of sealed at-tics to reduce the chance of moisture accumulation in the attic. These requirements have been in the codes for a relatively short time and remain the subject of continued debate at ICC as advocates of sealed attics work to improve the code language in response to concerns about performance issues from the field.

Traditional construction methods for wood-framed buildings include ventilated attics (with insulation at the ceiling level) as a means of isolating the roof assembly from the heated and cooled space inside the building. Attic ventilation makes sense for a variety of reasons. Allowing outside air into the attic helps equalize the temperature of the attic with outdoor space. This equalization has several benefits, including lower roof deck and roof covering temperatures, which can extend the life of the deck and roof covering. However, it is not just temperature that can be equalized by a properly ventilated attic. Relative humidity differences can also be addressed by vented attics. Moisture from activity in dwelling units including single-family residences and other commercial occupancies can lead to humidity entering the attic space by diffusion or airflow. It is important to ensure moisture is removed or it can remain in the attic and lead to premature deterioration and decay of the structure and corrosion of metal components, including fasteners and connectors.

In northern climate zones, a ventilated attic can isolate heat flow escaping from the conditioned space and reduce the chance of uneven snow melt, ice dams, and icicle formation on the roof and eaves. Ice damming can lead to all kinds of moisture problems for roof assemblies; it is bad enough that roof assemblies have to deal with moisture coming from inside the attic, but ice damming can allow water to find its way into roof covering assemblies by interrupting the normal water-shedding process. For buildings with conditioned space, the attic can isolate the roof assembly from the heat source but only if there is sufficient ceiling insulation, properly installed over the top of the wall assemblies to form a continuous envelope. Failure to ensure continuity in the thermal envelope is a recipe for disaster in parts of the country where snow can accumulate on the roof.

Accessory buildings, like workshops, that occasionally may be heated with space heaters or other sources are less likely to have insulation to block heat flow to the roof, which can result in ice damming. Ventilating the attic can prevent this phenomenon.

Accessory buildings, like workshops, that occasionally may be heated with space heaters or other sources are less likely to have insulation to block heat flow to the roof, which can result in ice damming. Ventilating the attic can prevent this phenomenon.


For unheated buildings in the north, ice damming is less likely to occur, unless the structure is occasionally heated. Accessory buildings, like workshops, that might be heated from time to time with space heaters or other sources are less likely to have insulation to block heat flow to the roof. In these situations, a little heat can go a long way toward melting snow on the roof.

While the ice damming and related performance problems are a real concern even for accessory structures, it is the removal of humidity via convective airflow in the attic space that is the benefit of ventilated attics in accessory structures. We know that moisture will find its way into buildings. Providing a way for it to escape is a necessity, especially for enclosed areas like attics.

There are many types of accessory structures, and some will include conditioned space. Depending on the use of the structure, moisture accumulation within the building will vary. For residential dwelling units, building scientists understand the normal moisture drive arising from occupancy. Cooking, laundering and showering all contribute moisture to the interior environment.

The IRC and IBC include requirements for the net-free vent area of intake (lower) and exhaust (upper) vents and also require the vents be installed in accordance with the vent manufacturer’s installation instructions. The amount of required vent area is reduced when a balanced system is installed; most ventilation product manufacturers recommend a balance between intake and exhaust. The IRC recommends that balanced systems include intake vents with between 50 to 60 percent of the total vent area to reduce the chance of negative pressure in the attic system, which can draw conditioned air and moisture from conditioned space within the building. This is less of an issue for non-habitable spaces from an energy-efficiency perspective, but moisture accumulation is a concern in all structures.

PHOTOS: Lomanco Vents

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You Can Influence Codes and Standards

As associate executive director of the Washington, D.C.-based EPDM Roofing Association (ERA), I focus a great deal of my time and energy on the codes and standards that regulate or guide the roofing business. In the current environment, driven by constant upgrades in technology, as well as the need to save energy, these codes—and the standards that often inform them—seem to be undergoing steady revision. Believe it or not—and the word “geek” does come to mind—I find participating in this process extremely interesting. In fact, following and sometimes influencing emerging codes and standards is among the most important responsibilities of my job.

I’ll be the first to admit that a detailed review of a standards manual is probably not anyone’s idea of exciting reading. But given the importance of codes and standards to the construction industry, we ignore them at our own risk.

For a start, what’s the difference between a code and a standard? Ask enough people in the roofing industry and you will get a variety of answers. But generally, codes are the “top-tier” documents, providing a set of rules that specify the minimum acceptable level of safety for manufactured, fabricated or constructed objects. They frequently have been enacted into local laws or ordinances and noncompliance can result in legal action. Standards, on the other hand, establish engineering or technical requirements for products, practices, methods or operations. They literally provide the nuts and bolts of meeting code requirements. If codes tell you what you have to do, standards tell you how to do it. Frequently, standards—especially “voluntary consensus standards”—are the precursors for what becomes law years down the road.

ERA has represented the manufacturers of EPDM roofing for more than a decade. Through the years, we have learned the importance of interfacing with standard-setting and regulatory bodies. One of our first, and most important, learning experiences was working with the Northeast and mid-Atlantic states when they issued regulations designed to achieve federally mandated air-quality standards. (See the article in Roofing’s September/October 2014 issue, page 58.) The initial regulations, which lowered the amount of VOCs in many roofing products, were based on those used in southern California and incorporated provisions that were effective in the climactic and market conditions of that state. But states in the affected areas, from Virginia to Maine, confronted a situation where the new regulations threatened to bring the roofing industry to a sudden halt. In some instances, no adhesives and sealants were available to meet the new standards. And the new products, when they became available, would need to be effective in very cold climates totally unlike those on the West Coast.

ERA worked with officials throughout the impacted areas, helping to create “phase-in” schedules that would give industry enough time to develop products to meet the new standards. In state after state, the local regulators welcomed our input. Our point-of-view was based on a deep understanding of the business needs of our industry. Just as important, we understood the science behind the proposed regulations and could work with the regulatory bodies to ensure the air-quality needs and the needs of the roofing industry were met.

This experience has informed our ongoing approach to code-setting and regulatory bodies. Since our work with the states setting VOC standards, we have invested staff time and resources to stay current with and even ahead of proposals that would impact our members and their customers. We have testified before the South Coast Air Quality Management District in California on its proposal to limit VOCs. ERA has organized an ad-hoc coalition to successfully oppose an unnecessarily stringent proposal to require reflective roofs in the Denver area. And our organization is currently providing input to Atlanta-based ASHRAE’s efforts to clarify its regulation regarding air leakage. This issue—of great importance to the roofing industry—relates to other work being done in ASHRAE working groups and subcommittees on thermal bridging, as well as the definition of walls and wall assemblies. ASHRAE has convened an “Air Leakage Work Group” whose charge is to review the pertinent sections of Standard 90.1 and make recommendations for revising it. ERA staff will be present at this group’s meetings and will once again provide input based on the expertise of our members.

When I work with code-setting and regulatory groups, I am reminded of that very familiar saying, “It’s not whether you win or lose, it’s how you play the game.” Based on our work at ERA, I’d like to revise that. Your skill at “playing the game” will definitely influence whether you win or lose. Our experience tells us that staying involved with regulatory groups and providing them with input based on firm science and field experience leads to a winning outcome for the roofing business.

Increased Thermal Values Affect an Existing Roof Edge

Recent code and standard development has resulted in increased thermal insulation. This increase has required greater and greater insulation thicknesses, which are even thicker when
tapered insulation is added. This roof system thickness, especially in reroofing design, has thrown a curveball to many designers: How should they address existing rooftop conditions?

On a recent project in which the roof sustained a wind event, investigation for the design of the new roof edge and system found multiple concerns: open metal stud cavities to the parapet, open metal panel joints, wood and substrate boards attached with drywall wall screws and moisture drive concerns. This information led to the design of one of the author’s most complicated roof edges.

Photo 1: On a recent project in which the roof sustained a wind event, investigation for the design of the new roof edge and system found multiple concerns: open metal stud cavities to the parapet, open metal panel joints, wood and substrate boards attached with drywall wall screws and moisture drive concerns. This information led to the design of one of the author’s most complicated roof edges (see Figure 1).

I have successfully dealt with this for more than three decades and mostly with ease. However, based on the fight being put up by the Chicago Roofing Contractors Association (CRCA), you would think it is putting contractors out of business rather than having the potential to increase their bottom lines.

Consequently, this will be the first of several articles discussing how designers can deal with existing conditions on the roof when increased thermal values are required. This article will explain the roof edge—the first defense against wind uplift and often an aesthetic concern. Future topics will include drains, roof curbs, access doors, windows, RTUs and plumbing vents.

WHY THE NEED

Twenty-five or 30 years ago, insulation was what you placed on the roof deck to act as a separator between the roof cover and roof deck, especially with the increased use of fluted steel decks instead of monolithic-type decks, like concrete, gypsum, wood and cementitious wood fiber. Prior to that, roof covers were often placed directly on these monolithic roof decks sans insulation.

On a recent project in which the roof sustained a wind event, investigation for the design of the new roof edge and system found multiple concerns: open metal stud cavities to the parapet, open metal panel joints, wood and substrate boards attached with drywall wall screws and moisture drive concerns. This information led to the design of one of the author’s most complicated roof edges.

Figure 1: On a recent project in which the roof sustained a wind event, investigation for the design of the new roof edge and system found multiple concerns: open metal stud cavities to the parapet, open metal panel joints, wood and substrate boards attached with drywall wall screws and moisture drive concerns. This information led to the design of one of the author’s most complicated roof edges (see Photo 1).

It has only been within the last 25 to 30 years that insulation has become an integral component of the roof system, often changing how the roof cover behaved. As energy and the conservation of energy became vogue, codes and standards became more stringent in regard to thermal insulation values. With the increase in R-value came an increase in the thickness of insulation. This in turn requires roof edges be higher to accommodate the increases in insulation, ultimately changing how the roof edge on buildings without parapets are designed.

Stacking wood to raise the roof edge is old school. Here you can see the new wood blocking is the second stacking over previously installed wood on a previous reroof.

Photo 2: Stacking wood to raise the roof edge is old school. Here you can see the new wood blocking is the second stacking over previously installed wood on a previous reroof.

The use of tapered insulation with thicknesses often above 12 inches changed how the roof edge is treated, especially in reroofing situations, which has resulted in design challenges. Add to this, modern building design that forewent parapets for gravel stop; the challenge of raising the roof edge to accommodate new insulation heights has dramatically increased.

The Washington, D.C.-based American Institute of Architects has issued a challenge to the design community to make all new construction Zero Energy Buildings (buildings that produce as much energy as they use) by 2030. Intuitively, more insulation (and perhaps fewer windows) will result in a building that uses less energy and, thus, more easily achieves a balance point.

To strengthen the multiple stacks of 2xs, 3/4-inch plywood is being added on the exterior.

Photo 3: To strengthen the multiple stacks of 2xs, 3/4-inch plywood is being added on the exterior.

This altruistic, far-reaching goal is being fought. CRCA, for example, is fighting the new code increases in roof insulation. Although the organization states a variety of reasons, it appears that the fear of owners delaying work that costs more because of increased insulation thickness is the greatest concern. This is interesting because design—by state mandate—is the purvey of licensed design professionals. Is the CRCA advocating design by non-licensed designers? I believe the CRCA’s position is foolish. Why would a predominately union-based contractor organization fight a code mandate that allows their members to increase profits? Perhaps the challenge by “right to work contractors” is greater than believed.

CONCERNS: LEGITIMATE OR NOT

There are a number of concerns, or design challenges, as I like to say, to raising the roof edge. For us architects, respecting the architect’s vision and design intent is often in conflict with what may need to be accomplished. I have worked with clients in buildings of note, designed by well-known architects, and have been able to respect every detail of the roof-edge vision. It is very difficult and challenging.

When stacking, wood joints should be offset and scarfed at 45 degrees.

Photo 4: When stacking, wood joints should be offset and scarfed at 45 degrees.

Another concern can be cost. Historically, a dimensional 2x was set at the roof edge and nailed; now we often raise the roof edge with prefabricated insulated curbs. Costs are always a concern but when budgeted correctly and the client is informed during the process, the project has always been realized within a year or two.

Another concern I often hear voiced is, “It’s difficult” or “I cannot figure it out”. When one considers that the roof edge must be (let’s say should be) tied to the building structure to resist wind loads, these are true concerns. These types of conditions often call on years of experience. Therefore, I say the challenge is on!

On this detail from an older project, the roof edge is being raised with multiple layers of 2 by 12s—a bit old school but easily performed. It is recommended to not specify preservative- treated wood, coated screws and off-set joints.

Figure 2: On this detail from an older project, the roof edge is being raised with multiple layers of 2 by 12s—a bit old school but easily performed. It is recommended to not specify preservative- treated wood, coated screws and off-set joints.

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The Attic Needs Ventilation but How Much Exactly?

Good news, roofing contractors: You do not have to be good with numbers nor do you have to enjoy math to be able to quickly—and accurately—calculate the amount of attic ventilation needed for residential attics. Here it is, a handy shortcut for quick calculations:

Intake exhaust airflow in a house

Intake exhaust airflow in a house

Attic square footage ÷ 2 = square inches of EXHAUST and square inches of INTAKE Net Free Area (NFA) needed. (NFA is the unobstructed area through which air can pass through a vent, usually measured in square inches. Ventilation manufacturers assign an NFA value to the non-motorized vents they make.)

This shortcut conveniently calculates the 2015 International Residential Building Code MINIMUM (IRC Section R806 – Roof Ventilation 1, which states, in part, 1 square foot of Net Free Area for every 150 square feet of attic floor space with the attic defined as length x width floor of the attic). The shortcut actually overestimates a bit but that’s OK. It puts the roofing contractor in the ballpark which is useful when estimating.

To calculate the allowable IRC EXCEPTION to the MINIUMUM (that is, 1/300 ratio) here’s the shortcut:

Attic square footage ÷ 4 = square inches of EXHAUST and square inches of INTAKE Net Free Area needed.

Here’s an example using the shortcut for the 1/150 Code Minimum.
Say the contractor is standing in front of a house that has an attic with 2,200 square feet.

    2,200 ÷ 2 =

  • 1,100 square inches of EXHAUST net free area needed
  • 1,100 square inches of INTAKE net free area needed
  • The next step is to select a suitable exhaust vent and intake vent that fits the roof design for best performance and best aesthetics. After that, find out the vent’s NFA as rated by the manufacturer. Divide the vent’s NFA into 1,100 to yield the number of vents needed (either in linear feet or units/pieces). That’s it. It’s time to install.

There is a longer “official” formula based on building code you can reference or point your clients to for reassurance that you know what you’re talking about. Most attic ventilation manufacturers list the longer formula on their websites and inside key product brochures. But the shortcut is just as good and faster!

Calculation Q & A

Here are the answers to the five most frequent questions pertaining to calculating attic ventilation.

1. “Why is it important that the amount of intake ventilation matches the amount of exhaust?”
The goal of an effective attic ventilation system is to help fight heat buildup inside the attic during the warmer months and moisture buildup in the colder months. Additionally, in climates where snow and ice are common, attic ventilation can help fight the formation of ice dams. To achieve these goals the attic needs cooler, dryer air entering low (near the eave or the roof’s lowest edge) so it can flush out any warm, moist air that may have built up inside, pushing it out through the roof’s exhaust vents positioned as close to the peak as possible. This balanced-airflow approach allows the air to “wash” the entire underside of the roof deck from low to high.

2. “What if it’s not possible to balance the attic ventilation system 50 percent intake/50 percent exhaust?”
If it cannot be balanced it’s better to have more intake than exhaust because it has been our experience most attics lack proper intake ventilation, which is the leading cause of venting callbacks. Additionally, any excess intake will become exhaust on the leeward side of the house because the intake vents on the windward side of the house will have “pressurized” the attic. As a result, the intake vents on the leeward side of the house will work “with” the exhaust vents to release air.

However, if the attic has more exhaust than intake it potentially can cause the extra exhaust to pull its missing intake from itself (if it’s a ridge vent) or from another nearby exhaust vent (from one wind turbine to another or one roof louver to another), which means possible weather ingestion.

3. “What if the roof has 40 feet of available ridge length but the math calls for only 30 feet of ridge vent needed?”
It is OK to install all 40 feet of ridge vent as long as it can be balanced with intake ventilation. If the amount of intake ventilation cannot match the entire 40 feet of ridge vent, consider reducing the width of the ridge vent slot (thereby reducing the vent’s NFA per linear foot) to accommodate the amount of intake NFA available. Doing this keeps the airflow continuous along the entire horizontal ridge and balanced high and low. As always, be sure the overall amount of ventilation meets code requirements.

4. “If attic access is not practical is there another way to measure the attic square footage?”
Ideally, the attic square footage would be measured at the attic floor length x width (regardless of roof pitch, by the way). If this is not possible, and the homeowner does not have any documentation on file listing attic square footage, you could use the footprint of the house (aerial view of the house) or the number of shingle squares (one shingle square equals 100 square feet) to estimate the attic square footage. Neither of the alternate measuring tactics, however, is as accurate as an attic floor measurement.

5. “How does roof pitch come into play when calculating attic ventilation?”
Current IRC requirements do not factor the role a roof’s pitch plays in the amount of attic ventilation needed, but ventilation manufacturers do. Generally, as the roof pitch increases the volume inside the attic also increases along with the amount of needed attic ventilation. Here’s a rule of thumb to follow:

  • Up to 6:12 roof pitch use the standard formula as explained in this article.
  • 7:12 to 10:12 roof pitches increase the amount of ventilation by 20 percent.
  • 11:12 roof pitch and higher increase the amount of ventilation by 30 percent.

For projects involving vents with motors, the calculation formula is different.