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ASCE 7, Uplift Ratings and Warranties

Posted By Western States Roofing Contractors Association, Monday, July 15, 2019

Greetings WSRCA Members,

As a follow-up to the Western Roofing Expo Seminar “Roof Wind Speeds: ASCE 7, Uplift Ratings & Warranties” Brian Chamberlain of Carlisle Construction Materials is releasing his PowerPoint presentation to the WSRCA membership for their roofing design library.
 
An ongoing issue that frustrates the industry as a whole is the confusion in how a roofing assembly will meet the building code, will meet an uplift rating, and be warranted based on local wind speeds. Since local wind speeds is the common factor in all three, an understanding of how wind speed is used associated to each needs to be clarified. This presentation focuses on the process, from uplift to warranty.

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LEGAL  DISCLAIMER

All rights reserved.  All content (text, trademarks, illustrations, reports, photos, logos, graphics, files, designs, arrangements, etc.) in this Technical Opinion (“Opinion”) is the intellectual property of Western States Roofing Contractors Association (WSRCA) and is protected by the applicable protective laws governing intellectual property. The Opinion is intended for the exclusive use by its members as a feature of their membership. This document is intended to be used for educational purposes only, and no one should act or rely solely on any information contained in this Opinion as it is not a substitute for the advice of an attorney or construction engineer with specific project knowledge. Neither WSRCA nor any of its, contractors, subcontractors, or any of their employees, directors, officers, agents, or assigns make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use (or the results of such use) of any information or process disclosed in the Opinion.  Reference herein to any general or specific commercial product, process or service does not necessarily constitute or imply its endorsement or recommendation by WSRCA. References are provided as citations and aids to help identify and locate other resources that may be of interest, and are not intended to state or imply that WSRCA sponsors, is affiliated or associated with, or is legally responsible for the content reflected in those resources. WSRCA has no control over those resources and the inclusion of any references does not necessarily imply the recommendation or endorsement of same.

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Condensation Potential & Damage Related to White & Light-Colored Roof Systems

Posted By WSRCA Technical Advisory Section, Tuesday, April 9, 2019

 

Greetings WSRCA Members,


Issues surrounding reports of condensation beneath light-colored single-ply roof membranes in some climates has been one of the more discussed industry-related topics over the past decade. Looking back, it appears that, building owners or tenants would report a mysterious “leak” or water intrusion into interior conditioned space and simply suspected that it was a leak likely associated with a weather event. As more and more of these situations were reported and then evaluated by the roofing contractor or professional roofing consultant certain patterns began to emerge in various climactic zones and general type(s) of roof assemblies.

Many of the similar roof system commonalities consist of mechanically-attached, white or light-colored single-ply roof membranes, installed over wood or steel roof decks with no vapor retarder. Of these roof systems reported as problematic, numerous lack multi-layers of insulation (with offset and staggered joints) and reportedly some have only one layer of insulation, and that is believed to have exacerbated the situation. As evaluations continued, the presence of interior-generated moisture as well as the lack of a vapor retarder and adequate ventilation was determined to be associated with condensation, forming on the underside of the roof membrane or roof deck, rather than a leak caused by some defect or puncture within the roof membrane.

WSRCA has been monitoring issues of condensation and moisture accumulation reported with mechanically-attached, white and light-colored single-ply roof systems, which were constructed without a vapor retarder, and we offer the following information to our Members. As this Bulletin will clarify not all roof systems may be appropriate for all climates.

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Roof Coatings Review: How Chemistry Impacts Quality

Posted By George Daisey, The Dow Chemical Company, Friday, January 25, 2019

Courtesy of: George Daisey — The Dow Chemical Company

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Installing or restoring a roof can be a tremendously complicated endeavor. There are single ply membranes, roof systems, coatings, concrete, metal and many more variations to choose from, which leads anyone to ask what substrate do I choose? To add further complexity, within the coatings option alone there are a variety of product types available: silicone, acrylic, polyurethane, and asphalt? Each presents notable features, strengths, and weaknesses to consider.

 


ROOF COATINGS MARKET OVERVIEW

 

The roof coatings market in the Unites States is a growing, vibrant market. According to data from the US Census Bureau combined with Dow internal analysis, it’s estimated the total US Construction Market is valued at approximately $1.1 trillion. Roofing is a little over 1% of that total which still represents a staggering $14 billion value. Within the scope of roofing, is a bright and shining market called roof coatings. The roof coatings market is rapidly approaching 6% of the total roof market with a value of approximately $780 million (see Figure 1.). There are many factors contributing to this growth but I will mention just one: the ever-aging building inventory. As buildings get older it becomes more common that two roof systems have already been installed and doing a third roof system either means tearing the first two completely off and starting over, or applying a maintenance product like a roof coating. In terms of cost savings and less impact on the environment, roof coatings win that debate almost every time.

 

In terms of growth, all three of these market segments can be described as healthy and growing. The same sources of information describe the total construction market growing at a compound annual growth rate (CAGR) of 8.2%. The $14 billion roofing segment is growing at 5.2% CAGR, and the roof coatings segment is humming along at a 4.7% CAGR. Compare this to the US GDP (Gross Domestic Product) which during the same period grew at a modest 2.4% CAGR. During that same period the US GDP was valued at $17.9 trillion; the US Construction market represents over 6% of the total US GDP. All these numbers simply show that these markets are large, vibrant, growing and poised to continue delivering advancements.

 

 

 

 

In fact, if we look at data spanning 2011 through 2016 we see the US roof coatings market growing at a rate of 5.2% CAGR, and that rate appears to be steadily increasing year over year. Starting from a total market value of $653 million in 2011, the growth rate has steadily increased on average to reach an annual growth rate in 2016 of 7.8% CAGR.

 

 

The two fastest growing segments in the roofing market are Thermoplastic Polyolefin (TPO) membranes and roof coatings (see Figure 2.). The tightening regulations on energy efficiency and lowering Volatile Organic Compounds (VOCs) have fueled demand for energy-efficient and low VOC products like TPO membranes and roof coatings.

 

Roof coatings show steady growth but indicators express the fastest growing portion of the roof coatings market is in higher performing coatings. It is easy to drive volume with lower cost products, but when growth is seen in higher value portions of a segment, there is good news for all parties. This means the customer is moving towards higher performing products that will deliver more value and longer service lifetime. The contractor is able to capture more value by selling and installing higher value products, and the manufacturer is also benefiting by offering the contractor higher value and higher performing products.

 

 

WHY CHOOSE A ROOF COATING

 

With so many choices for roofing, why would you choose a roof coating? There is no one answer to this question. Roof coatings come in many varieties not limited to water-based, solvent-based, reflective, non-reflective, thick-film, thin-film, white, black and all colors in between. Where do I start?

 

First, let’s answer the question posed above; why choose a roof coating? The first answer that often comes to mind is sustainability. In the United States alone, more than 251 million pounds of waste finds its way to landfills and nearly 40% of that waste comes from construction projects1. According to a Construction and Demolition Recycling article published in March 2018, global construction waste will double from the 1.3 billion ton total in 2012 to 2.2 billion tons by 2025. Identifying volumes of particular waste products is often difficult due to the variety of classes assigned to waste products; although certain roofing materials like shingles, asphalt and concrete are often mentioned in published waste studies.

 

If we truly want to offer sustainable products that make a difference to our environment, roof coatings are a great way to accomplish this objective. The application of a roof coating can extend the life of an existing roof and minimize the need to tear off a roof and send those materials to a landfill. In fact, whether the roof coating installation is new or retrofit, regularly scheduled recoating of that roof can reduce the need to landfill the original roofing assembly and lead to a viable solution for that roof. Looking for a sustainable solution? Then roof coatings are your answer!

 

How about sustainability from the standpoint of energy consumption? Energy efficiency is becoming more important to everyone. From the building owner dealing with utility bills to the occupants dealing with comfort level of the built environment, energy efficiency and performance of buildings is important. One of the most impactful jobs I ever participated in was a production facility where the building owner needed eight HVAC units to cool the building and office areas still never reached below 76 degrees. The roof was a black surface and the owner hired a contractor to convert the roof to a reflective surface by applying a reflective roof coating. After the installation, the owner stated that he was able to shut down three of the HVAC units and maintain a comfortable 72 degrees in the office spaces. That’s a win for everyone involved from contractor to owner to occupant.

 

Climate change is a hot topic almost everywhere you go, from construction sites to conference room meetings; even to your social media conversations. Everyone is talking about climate change, the environment and our planet. We all want to live better. Whether you believe reports of global warming, global cooling, and climate change or subscribe to none of it, constructing sustainable buildings and saving energy enables us to build a better future. Roof coatings can be a huge part of any sustainable, energy efficient building design project.

 

A building owner or other key decision-maker is often confronted with the choice of maintenance versus capital investment for a roofing project. A capital investment often means the cost of that roof installation is depreciated over many years; whereas a maintenance project can often be deducted in the same tax year. Most roof coatings installations fall under the maintenance category which allows the building owner to deduct the costs immediately. Note, tax laws change frequently; always check with your tax advisor to verify. This life cycle cost analysis compares two roof maintenance scenarios to demonstrate the value of roof maintenance.

 

Easy – and quiet – installation is a winner and roof coatings can deliver this in almost every situation. When a tear-off and complete roof assembly installation is done, there is often major disruption of building activities as well as areas around the building. Large trucks hauling materials in and waste out.

 

Sections of the parking lots cornered off to allow for trucks and materials to be moved and stored. Let’s not forget the dust and debris generated during construction. But many roof coatings jobs can be done in “stealth mode.” Buckets, drums or even totes of roof coatings can be delivered to a job site and transported up to the roof without many people aware that it is happening. I’ve personally been on jobs where the buckets are transported up a service elevator to the roof and the occupants do not know the roof is being coated!

 

We choose products because we want them to perform well. Roof coatings not only protect the existing roof and extend its service life, but roof coatings can deliver measurable performance. A roof coating may offer one or more of the following performance benefits: extended service life, water resistance, waterproofing, enhanced solar reflectivity and/or thermal emittance. Often, a roof coating enhances the appearance as well be transforming a dingy, dirty roof into beautiful colors ranging from basic white or black to a variety of highly decorative shades.

 

Selecting a roof coating for its variety of benefits is a first step. Now comes the hard part – which type of roof coating do I choose? Let’s explore some of the most common options on the market today, including their benefits, challenges and typical service life.

 

 

ACRYLIC

 

Acrylic roof coatings can be based on 100% acrylic or styrene-acrylic copolymers. Focusing on 100% acrylic roof coatings, these coatings offer excellent durability as well as the following typical properties: UV resistance, good permeance, dirt resistance, water resistance, and abrasion resistance. Acrylic coatings are water-based, easy to apply, easy to cleanup, and cure times can be tunable from several hours down to several minutes. Acrylic coatings are often installed as coating-only, but a growing sub-segment of acrylic coatings is as part of a liquid-applied membrane. Those familiar with acrylic decorative paints are familiar with a wide color palette, but for roof coatings that can vary. Steep slope thin film roof coatings can be supplied in a diverse color palette, but low slope elastomeric acrylic roof coatings are limited to white or light pastel colors. Deeper colors in these elastomeric coatings are possible to formulate but these colors often do not hold pigment as well, which leads to other technologies being used when deep colors are required. Acrylic roof coatings are limited to good weather conditions during installation because they are water-based. Excessive humidity or extreme temperatures can limit the success of an acrylic roof coating installation. Constant exposure to ponded water is also challenging for most acrylic roof coatings, resulting in impaired adhesion, blistering and delamination. However, the formulating space for acrylic roof coatings is wide; hence coatings can be formulated into anything from an economy coating up to an exceptionally high performing, durable coating. This variety makes acrylic roof coatings a great choice for the contractor looking for anything from an economical, low service life roofing solution up to a multi-decade lifetime roofing solution.

 

 

STYRENE-ACRYLIC

 

Styrene-Acrylic copolymers are a subset of the acrylic roof coating technology and should be treated separately. At a fundamental level, the styrene monomer is not as UV stable as the acrylic monomers used in roof coatings. Combining styrene with acrylic monomers to form a styrene-acrylic copolymer can deliver good performance properties; however, notably high performance is difficult to achieve versus the juggernaut of acrylic-acrylic copolymer interactions. In the roof coatings market, styrene-acrylic coatings are usually found in the economy space or in the lower warranty products. The good news is that styrene-acrylic roof coatings do have some notable performance properties, including excellent adhesion to metal and concrete and re-coats over existing acrylic roof coatings.

 

 

SILICONE 

 

Silicone roof coatings are all the buzz in the roof coatings industry. These coatings are not water-based and come in either low solids (~67%) or high solids (~98%) formulations. Silicone roof coatings are extremely resistant to water absorption, with some products literally having 0% water absorption according to standard ASTM D471 tests. The silicone polymers used in these coatings are UV light stable, do not degrade when exposed to sunlight, and thus offer one of the highest service life guarantees of any coatings option per installation. For commercial roofing, ponded water areas are the most challenging space on a roof for any coating, but silicone roof coatings are specially designed to perform well in those high moisture situations. A few challenges do exist for silicone roof coatings; including the need for primers over most surfaces, poor asphalt bleed resistance, difficulty to recoat, and low abrasion resistance. However the long service life and water resistance make the silicone roof coating a popular choice for low slope commercial roofing. Due to the slippery nature of the surface on a silicone roof coating, they are often not recommended for steep slope roofs.

 

 

POLYURETHANE 

 

Polyurethane (PU) chemistry delivers some noteworthy properties versus the coatings already discussed. A PU roof coating will often offer exceptionally high tensile strength and elongation versus other technologies. In situations where high tensile strength, toughness and chemical resistance are desired, PU roof coatings are an excellent choice. Adhesion and water resistance are often very good with PU roof coatings. It is important to note that PU coatings can come in either aromatic or aliphatic type chemistries. Only the aliphatic type are UV stable and offer long-term durability. These coatings are solvent-based and do need specialized spray equipment separate from either silicone or acrylic.

 

 

ASPHALT

 

Asphalt coatings are the oldest technology discussed in this article. The use of asphalt can be traced back to the ancient cultures like Greece and Babylon2. In fact, the earliest known use of asphalt dates back to around 615 B.C. when King Nabopolassar paved the streets of Babylon with asphalt and burned brick so he could have easy access in and out of his palace. In modern day roof coatings, asphalt coatings come in a variety of forms. There is traditional hot mop asphalt where the solid asphalt is heated and melted before being rolled or broomed onto a roof. Newer versions of this black color coating are in emulsion form where the asphalt is emulsified in water either through mixing with surfactants or high pressure processes. Further differentiation is between traditional black asphalt coatings and the newer silver or reflective asphalt coatings. Both in solvent and water-based emulsion form, the reflective asphalt coatings fit in a niche space between non –reflective and highly reflective roofing products. Hot mop asphalt and cold-applied asphalt emulsion are often applied to the roof as the waterproofing layer. With their near-zero permeance and hydrophobicity, there is no better waterproofing coating for roofing than asphalt coatings. These basecoat/primer coatings can then be top-coated with reflective aluminized asphalt or acrylic roof coatings. In some cases, the desire is to have a black surface so the asphalt coating is the final coat as well. The reflective aluminized asphalt coatings have good solar reflectivity and low thermal emissivity giving them a significant energy value proposition. Lifetime expectancy of aluminized roof coatings have improved over earlier incarnation of the technology due to improved formulation quality and refinement of the aluminum flake. In climates or situations where both very high reflectivity and emissivity are not desired, the moderate energy performance of the aluminized roof coatings can be the best choice.

 

 

SEBS 

 

Styrene Ethylbutylene Styrene or SEBS coatings are solvent-based coatings that offer excellent water resistance and very low permeance. Often SEBS is positioned against acrylic roof coatings as having an extended season of use; not as subject to the cold temperatures encountered in the shoulder seasons. SEBS coatings can be described as super-hydrophobic and will have a moderate service life versus silicone or acrylic roof coatings. The challenges for SEBS coatings include high VOCs and limited color option; typically only sold in white according to leading distributors of the product.

 

 

POLYUREA

 

Polyurea roof coatings are a very small percentage of the roof coatings market, but they offer an excellent property balance and can be the right choice for many roofs. Polyurea roof coatings are great waterproofers, have excellent chemical, abrasion and corrosion resistance and have an extended application season versus water-based systems. Some of the challenges are high VOCs and the reactive chemistry. An acrylic roof coating will dry by evaporation of water typically over a few hours, whereas the polyurea chemistry is reactive causing the coating to cure in a matter of seconds. The applicator must have a high skill set to spray this type of coating. Exterior durability is moderate, but long service life is never the driver for polyurea coatings; it is usually the chemical resistance or waterproofing properties that drive the use of polyurea.

 

 

PVDF

 

Polyvinylidene Fluoride or PVDF coatings are different from the previously discussed coatings in many ways. First, they are not applied to commercial roofs in thick films. Often a PVDF roof coating is applied at 2 to 4 dry mils thick. The cost per pound of a PVDF coating is much higher than other technologies, but is counter-balanced by the performance it can deliver in a thinner film. The benefits of PVDF over other coatings include improved dirt pickup resistance, long-term reflectivity, long-term durability, water repellency and mildew/algae resistance. Colors are no challenge for PVDF as they can be supplied in a diverse color palette. The main challenge is balancing the hardness and toughness of the PDVF coating versus the flexibility of the elastomeric basecoats often applied before the PVDF coating. PVDF coatings have advanced over the years and though earlier versions suffered from cracking issues, newer offerings have improved their crack resistance. It is always a challenge to apply a hard, rigid coating over a soft flexible coating, which must be understood by the contractor/applicator.

 

 

CONCLUSION

 

There are a diverse variety of roof coating technologies available in the North American market. Each roof coating technology has its noteworthy balance of properties and features that need to be understood by the buyer and user to determine the best option for intended use. Beyond roof coating product properties, type of substrate, service life, maintenance planning, sustainability benefits, and cost are considerable factors to help the coating chosen to meet the needs of the job.

 

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1 Mike Hower, Marketing Communications Manager, Carbon Lighthouse, 2013

 

2 https://actionasphalt.net/storied-history-asphalt-pavement/

 

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LEGAL  DISCLAIMER

All rights reserved.  All content (text, trademarks, illustrations, reports, photos, logos, graphics, files, designs, arrangements, etc.) in this Technical Opinion (“Opinion”) is the intellectual property of Western States Roofing Contractors Association (WSRCA) and is protected by the applicable protective laws governing intellectual property. The Opinion is intended for the exclusive use by its members as a feature of their membership. This document is intended to be used for educational purposes only, and no one should act or rely solely on any information contained in this Opinion as it is not a substitute for the advice of an attorney or construction engineer with specific project knowledge. Neither WSRCA nor any of its, contractors, subcontractors, or any of their employees, directors, officers, agents, or assigns make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use (or the results of such use) of any information or process disclosed in the Opinion.  Reference herein to any general or specific commercial product, process or service does not necessarily constitute or imply its endorsement or recommendation by WSRCA. References are provided as citations and aids to help identify and locate other resources that may be of interest, and are not intended to state or imply that WSRCA sponsors, is affiliated or associated with, or is legally responsible for the content reflected in those resources. WSRCA has no control over those resources and the inclusion of any references does not necessarily imply the recommendation or endorsement of same.

 

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IBC & ASCE 7-16 is Changing - WSRCA's Bottom Line

Posted By WSRCA, Tuesday, December 18, 2018

 

It has come to the attention of WSRCA’s Low-Slope and Industry Issues Committees that the 2018 International Building Code (IBC) is continuing to be adopted by more jurisdictions in the Western U.S. Please be aware that there are changes in the 2018 edition of IBC’s Chapter 15 for Roofing and its companion Chapter 16, which relates to wind-uplift resistance. These changes adopt, and requires use of the relatively new 2016 edition of the American Society of Civil Engineers “ Minimum Design Loads And Associated Criteria for Buildings and Other Structures” – (ASCE 7- 16 Standard) to determine wind-uplift design pressures for roof system attachment/securement. These changes are relatively complex, and Contractors may want to contact the Roofing Manufacturer for direction regarding roofing attachment (e.g., mechanical fastening schedules) or securement (e.g., low-rise foam adhesive bead size and spacing schedules). Contractors may also desire to carefully consider the potential affects (e.g., increase) with some materials, and labor for any additional mechanical attachment, foam adhesive, or other related roof securement needed.
 

Executive Summary:


Western States Roofing Contractors Association (WSRCA) believes that it is important to alert you to the value of being aware of changes to the code, as not knowing could have a dramatic effect on the success of any roofing or reroofing construction business.

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Western States Roofing Contractors Association
356 Digital Drive - Morgan Hill, CA 95037
Local: 650-938-5441  Toll Free: 800-725-0333
Email: info@wsrca.com

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Not a Member of Western States RCA?  Click Here to Join!
or call Toll Free 1-800-725-0333

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Zero Net Energy: Optimizing Energy Performance on the Roof with Spray Polyurethane Foam and Photovoltaics

Posted By WSRCA, Monday, December 10, 2018

By Rick Duncan, Ph.D., P.E.,

Technical Director, Spray Polyurethane Foam Alliance (SPFA)

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The sustainability focus in buildings has shifted lately to one on energy performance. Not only have building codes become more stringent, with a much greater emphasis on energy efficiency, but many incentives have been introduced and made available to owners, providing them with tax credits and savings for the integration of renewable energy sources such as solar onto their homes and projects.

Increasingly ambitious movements, including Passive House and Zero Net Energy (ZNE), are also gaining in popularity as immediate issues like climate change, and the catastrophic effects of it, are top-of-mind and ever present in the news.

Even though ZNE is a bigger energy goal than what is currently highlighted for many structures, architects, builders and owners are increasingly integrating sound energy practices in their buildings. As a key component of the building enclosure, roofing systems tend to transfer (i.e. lose) significant amounts of energy if not properly designed or well maintained. Thus, it is unsurprising that they are a key focus in buildings designed to minimize energy use.

Spray Polyurethane Foam (SPF) and Photovoltaic (PV) systems are now, more than ever, utilized together on the roof as a complete solution for energy savings. SPF reduces demand for the energy generated by photovoltaics, which can make a significant difference in ZNE buildings. When combined, they provide a joint solution for the generation of renewable energy, the conservation of heating and cooling energy, and, ultimately, the elimination of the structure’s dependence on fossil-fuel consuming electricity sources.

Regardless of whether ZNE is the end goal, SPF and PV integrated in roofing are an ideal combination for many structures, providing unparalleled return on investment through energy cost savings, as well as numerous additional benefits. However, contractors should be mindful of some important installation considerations when looking to join these two powerful systems on the roof of a building, to ensure highest possible performance and lifespan.

 

PV System Overview

PV cells are the basic unit used to convert light to electricity. Many PV cells are bundled together to make a PV panel, or module. PV panels are grouped electrically to create a PV string. And depending on the system size, two or more strings are combined to create a PV array.

The dominant type of PV panel used with SPF roofing is cSi, or crystalline silicon. cSi is a typically rigid panel with glass frame and metal frame and may be applied, unlike other dominant PV panel types, via rack installation methods.

A photovoltaic system includes many components in addition to the panels. Components include racks, rails, rooftop attachment devices, grounding systems, wiring and wiring harnesses, inverter(s), and connection to the main electrical panel. Components may also include control modules and storage batteries for off-grid PV system installations.

Photovoltaic panels must be handled and maintained with caution. Electricity is produced when a single panel is exposed to light, however, because a panel is not part of a circuit, that electricity will not flow until the circuit is complete. A worker may complete the circuit by connecting the two wires from the backside of a PV panel.

When maintaining a PV system, it may become necessary at some point to disconnect or remove an individual panel from a string or an array. The whole system must be shutdown properly as a precautionary measure to prevent shocks from occurring to workers and arcing between electrical connections. This “shutdown” procedure must be followed with precision as part of a lock-out/tag-out program and is provided by the inverter manufacturer. Under no circumstances should SPF contractors ever disconnect or decommission a PV panel or system unless they are trained and qualified to do so.  

 

Rooftop PV Installation Types for Use with SPF

Rooftop PV systems can vary significantly in size. Large footprint buildings can employ PV systems rated from 50 kW to 1000 kW or larger while residential rooftop PV systems are commonly 3 kW to 5 kW solutions.

Rooftop PV systems may be installed either on racks or adhered directly to the roof surface. When looking to combine PV with SPF, it is generally not advised to adhere or place the PV panels directly onto the roof surface. Solar heat as well as water can accumulate between the PV and roof coating and can negatively impact coating performance.  Moreover, panels applied directly to a low-slope roof will, in nearly all cases, not optimally align with the sun, which will reduce energy production. 

Non-penetrating rack systems may be placed directly on a rooftop and held in place with ballast. Racks may also be installed with penetrating supports that require flashings. Each type provides advantages and disadvantages. For example, ballasted racks may block water flow and affect drainage, while penetrations require leak and maintenance-prone flashings. SPF is unique in that it easily self-flashes around penetrating supports.

 

Design Considerations

Rack-mounted arrays with penetrating attachments are fairly lightweight at two to three pounds per square foot, and ballasted arrays add four to six pounds per square foot. With the latter however, more ballast is utilized at the perimeters and corners of a PV array. Thus, localized loading from ballast may reach as high as 12-17 pounds per square foot, which must be considered. Most SPF roofing systems have a compressive strength of 40-60 psi. 

PV panels add weight to a rooftop and this must be factored into the design and installation. Existing structures should be analyzed by a structural engineer to determine if the additional weight of the PV system is acceptable.

Additionally, roofs are required by codes to provide “live load” capacity, a measurement, which includes people, snow, and other temporary weight-bearing scenarios that may occur. The weight of a PV system is typically below the live load capacity, however in the absence of a structural analysis, the live load capacity will be reduced by the addition of the PV system. A final consideration is whether a PV installation will create new locations for drifting snow, which may add considerable weight to a roof, and must be factored in.  When determining key considerations for wind load and fire safety, best practices require deferral to the PV supplier.

Drainage on rooftops is important for safety of the structure and longevity of the roof. PV arrays often have many points of contact with a roof, and these are possible locations that will block or slow drainage.  PV racking should be positioned to minimize ponding water, and/or include methods such as notched pads to allow drainage under points of contact, especially for ballasted systems. 

Photovoltaic panels convert approximately 15-20 percent of light to electricity, leaving the remaining unconverted energy to be released as heat. Additionally, PV panels are more effective when their temperature drops. It is for each of these reasons that the majority of rooftop PV installations are designed to encourage airflow under panels, which reduces the temperature of the panels, improves conversion efficiency and releases heat effectively. Photovoltaic panels installed 4 to 5 inches above the roof will not change the temperature of the roof and, instead, provide shade to the surface of that roof. This additional shade may extend the life of SPF roof coatings.

 

Service Life and Maintenance

Ideally, a roof system, whether SPF or another material, and the PV system should have the same expected service life.  Removal (decommissioning) and reinstallation (re-commissioning) of a PV system is costly, and the cost should be weighed relative to the residual service life of the existing roof and cost of roof replacement or recoating at the time of PV installation.  Ballasted, rack-mounted PV systems are difficult, if not impossible, to reroof (or recoat) under and around.  Elevated racks with adequate space beneath may be able to be left in place when reroofing.  A PV system that covers, for example, 10% of the rooftop will be easier to relocate during reroofing than a PV system that covers 75% of the rooftop.  Building owners should be advised of future reroofing and maintenance costs with roof-mounted PV systems. 

The life expectancy of the SPF roof system should align with the service life of the PV system, and coatings factor in as they can extend the life and improve performance of SPF on the roof.

Roof systems used as platforms for PV systems must be tough and durable, and generally speaking, SPF has greater compressive strength as density increases. Higher density SPF systems may be preferred, especially when ballasted support systems are used. 

An SPF system will be stressed during the installation of the PV system and coatings and granules will help protect the roof during this time, and during scheduled maintenance. Because a roof surface below PV panels will likely not dry as fast as non-covered portions, coatings that stand up better to standing water and biological growth should be selected.  Installation of PV systems on SPF roofing will inevitably create additional foot traffic. It is important to protect heavily trafficked areas with additional coating and granules or walk pads. The cost to do so is low and will protect the service life of the roof.

All roof mounted PV systems should be inspected and maintained at least twice a year. Wiring, attachment points and flashings should be inspected and cleaning of the top surface of the PV panels may be required.

To maintain and service the roof and PV system, workers must be able to access both. PV systems should not block access to drains, penetrations, flashings, mechanical units or other rooftop equipment. Similarly, PV systems should be installed so maintenance workers can access wiring, inspect panel-to-racking connections, and properly clean top surfaces without stepping on PV panels.

 

Summary

In closing, while there are many considerations to the application of PV systems in combination with SPF roofs, the complete energy generation and conservation solution provided by the two integrated systems performs notably well. The energy cost and earth saving benefits are both undisputable and hard to ignore.

 

About the Author

Rick Duncan, Ph.D., P.E is the Technical Director of the Spray Polyurethane Foam Alliance (SPFA), the industry’s leading organization representing contractors, material and equipment manufacturers, distributors and industry consultants. The SPFA promotes best practices in the installation of spray foam and offers a Professional Certification Program to all those involved in the installation of the product.

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LEGAL  DISCLAIMER

All rights reserved.  All content (text, trademarks, illustrations, reports, photos, logos, graphics, files, designs, arrangements, etc.) in this Technical Opinion (“Opinion”) is the intellectual property of Western States Roofing Contractors Association (WSRCA) and is protected by the applicable protective laws governing intellectual property. The Opinion is intended for the exclusive use by its members as a feature of their membership. This document is intended to be used for educational purposes only, and no one should act or rely solely on any information contained in this Opinion as it is not a substitute for the advice of an attorney or construction engineer with specific project knowledge. Neither WSRCA nor any of its, contractors, subcontractors, or any of their employees, directors, officers, agents, or assigns make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use (or the results of such use) of any information or process disclosed in the Opinion.  Reference herein to any general or specific commercial product, process or service does not necessarily constitute or imply its endorsement or recommendation by WSRCA. References are provided as citations and aids to help identify and locate other resources that may be of interest, and are not intended to state or imply that WSRCA sponsors, is affiliated or associated with, or is legally responsible for the content reflected in those resources. WSRCA has no control over those resources and the inclusion of any references does not necessarily imply the recommendation or endorsement of same.

 

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Introducing Interior Protection for Reroofing Projects

Posted By Dana Whedon, TuffWrap® Installations, Inc., Friday, December 7, 2018

Roofing professionals face a myriad of challenges when assessing a reroofing project. Each facility is different and so is its roof. But one challenge that can be easily overlooked is what happens on the inside of the facility when work is being done on the roof outside.

It is well-known that dust and debris can easily find their way into a facility while reroofing is taking place. Dirt, metal shavings and pieces of roof deck are all potential contaminants. Even in the case of a simple overlay, the movement of the crew on the roof can disturb existing dust on the interior high structure areas. It is important that all project participants and customers understand the potential risks to the inside of the building and what their options are to avoid them.

If the facility does not seem to be sensitive in nature, it may seem acceptable to skip this step in the planning process. Regardless of the upfront perceptions around offering interior protection, many commercial/industrial roofers and roofing consultants have determined from experience that not unlike an insurance policy, professionally installed dust and debris containment is worth the time and investment.

This is because sensitive products are not limited to food, beverages and pharmaceuticals. Anything being manufactured, stored or displayed can be impacted by the introduction of reroofing dust and debris.

And the risk is not limited to products. If people will be inside the building throughout the reroofing activities, interior protection provides an extra level of assurance about their safety. Many times, a business cannot close or stop production during reroofing, making an ongoing clean up schedule impossible. Interior protection allows the work to continue safely without disrupting operating schedules.

So how does interior protection work? In the case of reroofing, a suspended cover is hung below the roof deck to capture falling debris. It is generally a reinforced poly that when installed properly, is fully sealed around any penetrations to avoid dust infiltration. In addition, many providers offer added material options such as antimicrobial, antistatic and flame resistant. The suspended cover is installed prior to the roofer beginning the tear off and is removed by the interior protection provider post-project.

If during the project planning, it is determined that interior protection could be beneficial, the next step is to contact a provider. Like any contractor in the construction business, an interior protection provider should have specific qualifications. The installation team should be OSHA certified, lift certified and professionally trained to install the solution. Ideally, they should have the ability to work with your project schedule and have a project manager readily available to address questions and concerns. Most importantly, their suspended cover solution should meet NFPA 13 in order to avoid compromising the fire sprinkler system.

Fire sprinklers are usually located in the same area where the suspended cover is installed. This would normally create an impairment. However, the interior protection industry has options to avoid this challenge. It is important to choose a provider that has the ability to install a solution that meets NFPA 13, allowing the fire sprinklers to function as designed.

By introducing interior protection upfront, any confusion or misgivings about the interior of the building is avoided. Throughout the project duration, customers can continue to utilize their facility without worrying about negative impacts to their products or daily operations. Ultimately, dust and debris containment not only contributes to overall success of the reroofing project but it gives the customer peace of mind.

Dana Whedon
Marketing Manager
TuffWrap® Installations, Inc.
www.tuffwrap.com

 
TuffWrap® Installations, Inc. is an innovative dust and debris containment company providing interior protection solutions to a variety of industries undergoing construction projects. Protecting our clients, their products and their brands from dust and debris is our priority.

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'Cool Roof' Legal Debate in Denver, Colorado

Posted By Western States Roofing Contractors Association, Monday, October 29, 2018

A year after passing “green roof” law, Denver suddenly the focus of 20-year “cool roof” debate

New law would force affected property owners to choose between creating green space, installing solar panels and saving energy.  

Courtesy of: The Denver Post  


The days of sprawling black roofs in Denver may be ending — but they won’t go quietly.

The Denver City Council will decide Monday whether to create a “cool roof” law for the city. The big hope is that requiring reflective, light-colored roofs on large buildings would lower ambient temperatures, fighting back against the city’s heat-island effect. “It’s not groundbreaking in Denver, but it’s one of the biggest” of the new cool roof laws, said Kurt Shickman, executive director of the Global Cool Cities Alliance.

“They’ll join a small number of big cities.” The change would affect new construction and reroofing projects for buildings over 25,000 square feet — not your typical home renovations. The new law also would force affected property owners to choose between creating green space, installing solar panels and saving energy. And, for once, many developers are looking forward to a new rule: It would replace the “green roof” law that voters approved last year, which would have required more costly rooftop gardens. The proposal has the support of green-roof organizer Brandon Rietheimer.  

 

Roofers vs. reformers

But even this smaller change has put the city in the middle of an ongoing debate between roofers and reformers. The council on Monday is likely to hear from industry representatives who say that the cool-roof mandate is an oversimplified approach for a complicated problem.

“Mandating a single component of a roofing assembly is just not what is good design practice,” said Ellen Thorp, associate executive director of the EPDM Roofing Association, which represents manufacturers of EPDM, a rubber membrane for roofs.

The trade association argued in a letter that cool roofs can cause two major problems in colder climates like Denver’s. First, they can purportedly accumulate moisture. Second, they are meant to retain less heat, which means heating bills can be higher. “Some of the best roofs on the market really were not going to be allowed, period,” said Jeff Johnston, president of the Colorado Roofing Association, who says that much of his Steamboat Springs business is still focused on dark roofs.  “Why eliminate it?”  

 

Attempting to adapt

The reason is simple, according to Katrina Managan, the city staffer who coordinated the roof revision. “The reason to do them is to adapt to climate change,” she said.

Denver could see a full month of 100-degree days in typical years at the end of the century, according to projections from the Rocky Mountain Climate Organization for a “high” warming scenario. And the impact will be worse in urban areas, where dry, unshaded rooftops and pavement are baked by the sun and heat the air around them. Urban environments can average up to 5 degrees hotter than the surrounding rural areas, and the difference can be much greater at times, according to the Environmental Protection Agency.

Cool roofs address part of that problem: They reflect the sun’s energy away and stay up to 60 degrees cooler than traditional roofs, the EPA reported. “It will save Denver a tremendous amount of money. It will create a huge amount of benefit through cooling. And it will set the example,” Shickman said. “It really does add to the argument that says we really should be considering this for almost all of our big American cities.”

City research found that the cool roof mandate would be more effective than the green roof initiative in combating heat, since the green roof requirement only covered parts of rooftops.

 

The bottom line?

Major cities began adopting cool-roof requirements nearly 20 years ago, with northerly Chicago among the first. It’s been joined by Philadelphia, Baltimore, New York City and Los Angeles, among others, according to GCCA. Much of the southern United States is now covered by the requirements, and San Francisco in 2017 adopted the first “green roofs” requirement.

“We’ve been in an epic fight between the industry and those of us on my side who are trying to push this forward,” Shickman said. Thorp, the EPDM Roofing Association representative, pointed to research to argue that Denver should proceed cautiously. Because cool roofs don’t get as hot, they can accumulate more condensation, which requires specialized designs to combat.

And she said that a cooler roof could mean higher heating costs and thus more carbon emissions in colder Denver. She acknowledged that the law would hurt sales of EPDM: Competing materials are cheaper and more popular for cool roofs. But she said that her clients also make those other materials. “They’re going to make the sale one way or another,” she said. Shickman countered that the companies are more heavily invested in EPDM, and therefore have a financial motivation to lobby against cool roofs.

Other materials “have been eating the lunch of EPDM,” he said. Thorp declined to disclose sales figures for the companies, but said the organization’s “primary driver” was to give roofers options. Cool roofs are already popular A city poll of roofers found that about 70 percent of new roofs in Denver are “cool.” “What we’re tending to find is most companies now are wanting to go to a light roof,” said Scott Nakayama, director of operations for Denver-based North-West Roofing.

“The amount that they’re going to save, as far as heating and cooling bills, tends to stand out.” His company has been installing about 20 light-colored roofs per year, and hasn’t encountered any of the issues raised by the EPDM Roofing Association, he said. Shickman points to this apparent lack of complaints as evidence that a well-designed cool roof can avoid moisture and other issues. They do come at a cost premium: Cool roofs can cost about 1.5 percent more than a traditional roof, according to city-commissioned research by Stantec, the engineering company.

Thorp said that estimate is too low. If the law is approved, it could take several years before it starts to have a regional effect, since roofs generally only need replacement every 20 years.

The rest of the details Under the change, developers of new builders can choose among the following options.

·       Install green space on the building or on the ground.

·       Pay for green space somewhere else.

·       Install renewable energy or a mix of renewable energy and green space.

·       Design the building for 12 percent energy savings compared to city standards, or achieve 5 percent savings plus green space.

·       Achieve either LEED Gold or Enterprise Green Communities certification for green design.

Existing buildings will have similar types of options, with different details.  

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LEGAL  DISCLAIMER

All rights reserved.  All content (text, trademarks, illustrations, reports, photos, logos, graphics, files, designs, arrangements, etc.) in this Technical Opinion (“Opinion”) is the intellectual property of Western States Roofing Contractors Association (WSRCA) and is protected by the applicable protective laws governing intellectual property. The Opinion is intended for the exclusive use by its members as a feature of their membership. This document is intended to be used for educational purposes only, and no one should act or rely solely on any information contained in this Opinion as it is not a substitute for the advice of an attorney or construction engineer with specific project knowledge. Neither WSRCA nor any of its, contractors, subcontractors, or any of their employees, directors, officers, agents, or assigns make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use (or the results of such use) of any information or process disclosed in the Opinion.  Reference herein to any general or specific commercial product, process or service does not necessarily constitute or imply its endorsement or recommendation by WSRCA. References are provided as citations and aids to help identify and locate other resources that may be of interest, and are not intended to state or imply that WSRCA sponsors, is affiliated or associated with, or is legally responsible for the content reflected in those resources. WSRCA has no control over those resources and the inclusion of any references does not necessarily imply the recommendation or endorsement of same.

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Technical Bulletin 2018-S1: Ice Damming on Cold/Ventilated Water Shedding Steep-Slope Roofs

Posted By Chris Alberts, Western States Roofing Contractors Association, Tuesday, September 4, 2018
Updated: Monday, September 10, 2018

Greetings WSRCA Members:

BACKGROUND INFORMATION:

During the past few winters, WSRCA Member Contractors in varying areas of the western U.S. have reported an increasing number and intensity of winter-time icedam formation and resultant damage at various buildings in the western states.

INTRODUCTION:

This Bulletin’s discussion of ice-dams, along with guidelines and suggestions for mitigation of ice dams, is focused on steep-slope roof systems in general and primarily on ventilated (i.e., theoretically vented, so “cold-in winter”) watershedding steep-slope roof systems. These ventilated/cold watershedding steep-slope roofs are frequently, though not exclusively, found on single-family and multi-family residential construction. These ventilated steep-slope roofs are also found on light commercial (e.g., dental and medical clinics, etc.) and some institutional buildings (e.g., schools, community centers, etc.). This document also considers ice-damming on warm (i.e., non-vented, but compact insulated) watershedding steep-slope roofs, which are frequently found with cathedral-ceiling or vaulted-ceiling construction on multi-story townhouses, other split-level residential, smaller scale commercial, and on many churches, and some other institutional projects.

THE ICE-DAM CYCLE:

Ice-dams are the naturally occurring eave edge refreezing of snow-melt water, typically at or upslope from the exterior wall line of a building. The subsequent repetitive back-up and refreezing of snow-melt along downslope roof perimeters and eaves is typically the initiator of melt-water (i.e., snow and/or ice melt) intrusion through layer(s) of watershedding roofing systems.

Five (5) stages of ice-dam formation are depicted and explained on the following pages. For reader clarity, the roof type sometimes used in heavy snow and ice climates have large Field-built ridge vent systems as is depicted in the following drawing excerpted from WSRCA’s Cold-Weather Tile Manual, Detail No. CWT10.

Thus, during a sub-freezing spell, a primary key to minimizing ice-dams is the reduction of snow-melt, which in turn may be mitigated by keeping the entire roof system or assembly below freezing temperature(s).

CONDITIONS AFFECTING ICE-DAM FORMATION:

Several controlling elements should be deliberated when considering steep-slope roof design or reroofing and the mitigation or “control” of ice-dams. Among the numerous items to be considered are:

• The climate the project is located in;

• The roof slope;

• The type of roof assembly (e.g., cold-ventilated roof or warm-compact insulated roof);

• The primary roof covering (e.g., asphalt shingles, tile, metal roofing, etc.);

• The roof design and vented or non-vented;

• Component configuration;

• Insulation;

• Ventilation;

• The building heating system;

• Potential air infiltration;

• The roof’s details and the layout of the roof including the related roof transitions (e.g., valleys, clerestory roof elevation changes where drifting can occur, etc.) and intersections (e.g., chimneys, skylights, plumbing vents, other roof penetrations, etc.).

Climate Considerations:

While technical resources are available for estimating the likelihood of ice-dam formation in various geographic locations, an empirical indicator is the history of ice-dam problems in the climatic location and/or region of your project. The long-term weather and climatic data, the experience and knowledge of local contractors, experienced roof designers, workers and building departments are the start to anticipating ice-dams and the potential means and methods to mitigating icedams and their affects.

Other climate-related factors include the effect of night-time clear skies, which accelerate the rapid cooling of roofs and refreezing of daytime melt-water, the orientation of the project roof, local topography and anticipated snow depths. Clear night-time sky radiative cooling often causes refreezing of snow-melt when freezing temperatures may not otherwise occur or be as severe on overcast or cloudy nights. Roof slopes oriented to the south experience greater snowmelt due to day-time solar radiation. Conversely, ice dams on roof areas oriented to the north may endure longer and prolong ice-dam issues. Local topography and wind patterns affects depth of snowdrifts, or inversely, snow scour. Counterintuitively, snow has some insulation capacity so that deep snow cover may adversely ‘warm’ (i.e., 33 degrees F) the roof deck of warm/compact roof assemblies. In addition, deep snow may block individual roof vents and ridge ventilation openings of cold/ventilated roof assemblies, thus accumulating attic heat, melting the snow cover and contributing to ice-dam formation.

Roof System / Roof Assembly Configuration:

Roof Type – As noted above, two general types of steep-slope roof assemblies may be considered concerning ice-dams: Cold/ventilated roof systems; and Warm/insulated compact roof systems. The physics of heat in these two roof types affects ice-dam formation. Cold/ventilated roof assemblies, if sufficiently ventilated, may allow less snow-melt because the sub-freezing air temperature in the ventilated roof cavity or space (e.g., the attic) keeps the roof sheathing, underlayment and primary roof covering (e.g., asphalt shingles, etc.) below freezing also. Warm/compact roof assemblies, in contrast, despite thick insulation, eventually conduct enough heat to melt snow cover.

Roof Configuration – Complex roof layouts or configurations can make for complex behavior of ice-dams. Interestingly, valleys, hips, overhanging eaves, closed or open soffits, headwalls, sidewalls, skylights and other roof elements can contribute to the complex behavior of internal heat flow and air movement, the success of ventilation air pathways, heat conduction and snow depth, including the effects of wind-driven snow drifting, which all can affect ice-dam

formation and severity. Interior elements, such as vaulted or cathedral ceilings, chimneys, the location of heater and heat registers, and others, can also significantly affect heat conduction and ventilation and so affect ice-dam formation and severity.

Extensive overhanging eaves warrant special caution because of the increased probability of upslope melt-water refreezing over large eave areas and the consequent likelihood of widespread damage. Short eaves, such as where fascia project only an inch or two for a ventilation gap, are near to the building’s heat which tends to keep melt-water in liquid state. Reaching the gutters, melt-water tends to refreeze because of freezing air on three sides: above, outboard and below. Longer eaves, projecting as much as several feet beyond the heat of the exterior wall, are that much more removed from the building’s heat and enveloped in subfreezing air that causes refreezing, ice dam build-up, resulting in water intrusion and damage.

Some have observed the formation of ice dams at extended eaves located above dark color south facing walls where solar heat builds-up below the eave. At compact insulated roof assemblies, some have chosen to extend the insulation through the eaves in order to minimize daytime heat transfer to the snow pack above the eave. To the contrary, some roofing contractors have reported skepticism of the function of insulated eaves for compact insulated roof assemblies as they have observed ice dam problems occurring during more severe winters. The several variables of orientation, solar radiation versus cloud cover, amount of insulation, daytime versus nighttime temperatures, mild versus severe climate patterns, and ventilated versus compact roof assembly indicate the topic of insulated eaves may be a subject for further examination.

Heat and Insulation – Insulation does not prevent the conduction of interior-generated heat through roof assemblies or into roof cavities and attics, but rather slows down the transfer of heat into the roofing system. Thicker insulations and higher thermal resistance (i.e., R-value) may minimize ice-dam formation during shorter duration freezes, but eventually allows snowmelt during longer periods of exterior freezes. As noted above, thick snow, which is a mild insulator, may affect the location of the melting plane within a roof’s snow cover. For example: a foot of lightweight fluffy snow may add insulation value of R-10 to more than R-20, above the roof covering. As a result, on warm/compact roof assemblies, the 33-degree or higher melt temperature may occur within the snow cover rather than on the surface of the roofing. Thermal bridging through fasteners, sandwiched sheet metal flashing flanges, and other non-insulation components may also contribute to the duration and volume of snow-melt and/or refreezing affects.

Air Infiltration – Air mass is able to transport many times more heat than is typically conducted through insulation. Therefore, air “leakage” from interior spaces (e.g., through unsealed can lights, kitchen range and/or bathroom exhaust fan ducting air leaks, etc.) into attics and roof assemblies may have a greater effect than insulation on snow-melt. Air exfiltration from building interiors into roof assemblies is more likely a concern in older roofs and older buildings, which are less airtight. Newer roofs are more likely to be ‘tighter,’ some of which may include an air infiltration barrier or vapor retarder. Vapor retarders may also perform as air barriers.

Vapor permeability of roofing materials plays a lesser, indirect role regarding ice-dams. A lowperm (i.e., vapor permeability unit of measure) rated ice-dam protection membrane installed above well-ventilated and properly insulated attic likely presents little, vapor/condensation issues, but achieving the “well ventilated and properly insulated” is difficult with some buildings. A low perm, ice-dam protection membrane above a warm/compact roof assembly, however, is sequentially misplaced as a potential vapor trap, which may cause condensation within the warm/compact roof assembly.

BUILDING CODE REQUIREMENTS & RELATED DATA:

The 2018 International Building Code (IBC) and International Residential Code (IRC) requirements for ‘Ice Barrier’ read similarly. For water-shedding roofs, ice barrier is required in regions where there has been a history of ice forming along the eaves causing water backup. Roofing contractors, roof designers and building owners should confirm the specific requirements for ice barrier with their local building department.

Ice barrier, per both the IBC and IRC, is required from a line 24-inches upslope of exterior walls to the lowest edges (e.g., to the fascia) of roof surfaces. It is prudent roofing practice to base this 24-inch upslope measurement from the interior face of the exterior wall. While WSRCA prefers the term ice-dam protection membrane, contractors, designers and owners should be aware of the I-Codes’ synonymous term ‘ice barrier.’ Ice-barrier, as defined by ICodes, is a minimum of two layers of asphalt saturated underlayment cemented together, or “self-adhering” polymer-modified bitumen sheet membranes.

IRC Figure R403.3(2) Air-Freezing Index an Estimate of the 100-Year Return Period, a nationwide contour map of freezing temperatures, may help identify ice-dam prone regions. A footnote indicates, “It is used as a measure of the combined magnitude and duration of air temperature below freezing.” Thus, it might be used in conjunction with NRCA recommendations, below. IRC Table R403.3(2) Air-Freezing Index for U.S. Locations by County compiles similar data in tabular form.

Industry Benchmark Guidelines:

WSRCA recommends ice-dam protection membranes “in cold climates where snow and ice are common” and “in areas of significant snow accumulation.” WSRCA further recommends icedam protection membrane “should be installed in all potential ice damming locations such as along downslope eaves in valleys, around chimneys, crickets, around roof penetrations, and up rake edges. At downslope roof edges it is recommended to extend ice dam protection membrane upslope a minimum of 24-inches inside the interior face of the exterior wall.” This means covering more than just the lowest 24-inches of eaves upslope of the fascia or gutter. Rather, cover all roof areas from the fascia/gutter line, upslope across all overhanging eave areas and exterior wall areas, then continue upslope 24-inches measuring from the interior face of the exterior wall.

NRCA recommends that ice-dam protection membrane be installed in locations where the average temperature for January is 30 degrees Fahrenheit or less. NRCA provides a map of such areas. Further, NRCA recommends ice-dam protection membrane be installed a minimum of 36-inches upslope of the outer wall’s interior line when the roof slope is less than 4 in 12.

In all cases, conservative judgement should be exercised while conforming to, or exceeding, the most rigorous requirements or benchmarks, whether Code, WSRCA, NRCA or others.

SOLUTIONS:

Solutions to ice-dam problems may best be interpreted as ventilation, ice-dam control or mitigation rather than complete prevention of ice-dams. Because of the broad variety and types of the current steep-slope watershedding roofs, existing as well as those yet to be designed and constructed, in conjunction with the variety of [micro-] climate conditions, the industry should understand that there are no universal and absolute solutions to ice-dam prevention.

For new roof projects, detailed design attention should be given to ventilation, insulation, icedam protection membrane, the membrane’s extent (e.g., distance upslope, potential number of plies, etc.), and whether there are or are not overhanging eaves. For existing roofs and reroofing projects, ice-dam protection membrane is a practical strategy of ice-dam control or mitigation of moisture intrusion and damage. WSRCA members should encourage clients to consider several strategies in addition to ice-dam protection membrane: retrofit of ventilation, sealing and airtight taping of interior penetrations that would otherwise allow interior air and heat leakage into the roof cavity, and the need for insulation review and upgrade or retrofit, or replacement in addition to ice-dam protection membrane(s).

Ventilation – Optimal ventilation, with regard to ice-dam mitigation, keeps the roof deck and roofing system below freezing, during periods of exterior freezes, by flushing air through, and thus heat out, of the attic or roof ventilation cavity. Venting of attics and cathedral ceiling roof cavities, utilizing downslope and companion upslope venting is the most common means for ventilation of steep-slope water shedding roof assemblies.

Historically, attic ventilation requirements prescribed by building codes were based primarily on condensation-related concerns – for example, roofs with vapor retarders are allowed less ventilation (1:300 ratio) than those without a vapor retarder (1:150 ratio). Ventilation for ice-dam control, however, is grounded on larger openings and cavities for moving larger volumes of sub-freezing exterior air into downslope eave (e.g., intake) vents, through the roof cavity or attic and out upslope roof vents (e.g., exhaust) or ridge vents. Whether for ice-dam control or condensation control, it is good basic roof design practice to balance eave ventilation intake-air openings in approximately 50-50 ratio with ridge or upslope exhaust-air openings. (See WSRCA Bulletin concerning roof ventilation.)

Cathedral ceiling roof assemblies, with ceilings attached directly to the underside of sloped roof rafters or trusses, are special cases of ventilated roofs. Research concerning roof ventilation for effective control of ice-dams on cathedral ceiling roof assemblies (see references) indicates that the necessary vent opening size and vent space above the insulation is related to the amount of roof insulation, roof slope and length of the slope. The research indicates that much larger openings and larger cavity height above the insulation is necessary-beyond that required by codes—for effective condensation and/or ice-dam mitigation. Vented nail-base insulation panels, though conceptually similar to “vented” cathedral ceiling roof assemblies, typically do not provide nearly sufficient ventilation and air-flow for ice-dam mitigation and condensation control in all such roof configurations.

Warm/compact steep-slope roof assemblies conduct heat through insulation over time and narrow closed cavities or spaces are susceptible to condensation, and contribute to ice-dam formation. Properly sized ventilation cavities, such as can be constructed with over-framing assemblies, located above a compact insulated roof assembly, can provide the ventilation necessary to move sufficient air under the elevated roof sheathing and thus reduce the likelihood of snow-melt and mitigate ice-dams.

Ice-Dam Protection Membrane / Ice Barriers – Both the International Building Code (IBC) and the International Residential Code (IRC) indicate that a history of ice-dam formation is prudent criteria for deciding to install an ice barrier (the IBC and IRC term) or ice-dam protection membrane (WSRCA preferred term) in roof assemblies. The IRC, however, requires ice barrier if adopted or specifically specified by the local building department in Table R301.2(1) the Climatic and Geographic Design Criteria.

 

CLICK HERE FOR THE FULL DOCUMENT...

 

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REFERENCE DOCUMENTS:

• WSRCA/TRI Tile Roofing Manual for Cold Climates, 1998, Reprinted 2005.

• Air Vent Inc. Attic Ventilation: Tips and Answers from the Experts December 2016.

• CertainTeed Shingle Applicators Manual, January 2011.

• Fryer, Mark; Brown, E. Staples; Design of Ventilated Attic Spaces for Buildings in Cold Regions; State of Alaska Department of Transportation and Public Facilities Division of Planning and Programming Research Section 2301 Peger Road Fairbanks AK 99701, January 1986.

• State of Alaska Department of Transportation & Public Facilities; Roofing Standards Manual, February 1986.

• Tobaisson, Wayne; Tantillo, Thomas; Buska, James; Ventilating Cathedral Ceilings to Prevent Problematic Icings at Their Eaves; Proceedings of the North American Conference on Roofing Technology September 1999, Toronto, Ontario.

• Holladay, Martin; How It Works: Ice Dams; Fine Home Building, December 2015 / January 2016.

• Holladay, Marin; Preventing Ice Dams; Fine Home Building, May 2011.

• Rupar, Maciek; Ice Dam Busting: Eradicating Ice Dams Begins Below the Roof Deck; Professional Roofing, June 2012.

• Hoffman, Jeffrey; An Ice Dam Analyzed; Journal of Light Construction, March 2010.

• Ireton, Kevin; Venting the Roof; Exterior Finishing Fine Home Building, June 2010.

• WSRCA Steep-Slope Committee; Laminated Shingles & Water-Shedding Roof Systems for Lower Slopes, January/February 2010.

• ARMA Asphalt Roofing Residential Manual Pages 47-48 Eave Flashing for Ice Dam Protection, 2006.

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LEGAL  DISCLAIMER

All rights reserved.  All content (text, trademarks, illustrations, reports, photos, logos, graphics, files, designs, arrangements, etc.) in this Technical Opinion (“Opinion”) is the intellectual property of Western States Roofing Contractors Association (WSRCA) and is protected by the applicable protective laws governing intellectual property. The Opinion is intended for the exclusive use by its members as a feature of their membership. This document is intended to be used for educational purposes only, and no one should act or rely solely on any information contained in this Opinion as it is not a substitute for the advice of an attorney or construction engineer with specific project knowledge. Neither WSRCA nor any of its, contractors, subcontractors, or any of their employees, directors, officers, agents, or assigns make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or any third party’s use (or the results of such use) of any information or process disclosed in the Opinion.  Reference herein to any general or specific commercial product, process or service does not necessarily constitute or imply its endorsement or recommendation by WSRCA. References are provided as citations and aids to help identify and locate other resources that may be of interest, and are not intended to state or imply that WSRCA sponsors, is affiliated or associated with, or is legally responsible for the content reflected in those resources. WSRCA has no control over those resources and the inclusion of any references does not necessarily imply the recommendation or endorsement of same.

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WSRCA Informational Bulletin 2018-II-2: Static Electricity and Roofing Adhesive Fire Risk

Posted By Chris Alberts, Western States Roofing Contractors Association, Monday, August 6, 2018
Updated: Tuesday, August 28, 2018

Greetings to Members of Western States Roofing Contractors Association:

 

Introduction:

WSRCA’s Industry Issues Committee is responding to reports from Member Contractors in the Western U.S. by preparing the following Information Bulletin regarding on-roof fires that have been caused by static electrical sparks during the application of single-ply membrane roofing using solvent-based adhesive.

 

Executive Summary:

Solvent-based adhesives may release fumes when their pails/containers are open and during application that can be a potential fire hazard during specific conditions and/or situations. A spark is all that is required, under certain conditions, to ignite such fumes. During dry outdoor ambient conditions, sparks can be caused by static electrical discharge. These three conditions can come together during a single-ply roofing installation and unexpectedly start a fire. Reports from the field indicate that this has been the case for more than one contractor recently, especially when weather conditions have been conducive to static electricity.

Reports from the field indicate that when relative humidity is very low, whether it be during cold, dry weather, or hot and dry weather, static electrical charges can build up during insulation roofing application. Most reports have involved steel roof decks and faced polyisocyanurate roof insulation and single-ply roofs. Static charges can be created when weather conditions are right and rigid foam insulation boards are slid or dragged across each other, when membrane sheets are moved over the installed insulation or over other thermoplastic roof membrane sheets, and just from walking on the insulation or insulated roof. If static charges have accumulated, spark(s) may occur when the metal bar of the adhesive roller or applicator handle touches the metal adhesive pail or container, or even when a worker’s skin or hand touches metal. Sometimes these sparks result in ignition of adhesive fumes and/or the adhesive itself during application. There are measures to be taken to help prevent the build-up of static charges, such as: by confirming that the existing building or building-under-construction is grounded, by taking care regarding how materials are moved and placed on the roof, wearing all cotton rather than synthetic clothing, walking carefully without shuffling, grounding equipment being used on the roof, just to name a few.

However, reports from the field where fires have occurred indicate that it is very important that the crew understand how to respond to and extinguish on-roof fires as soon as possible when they occur. It is also important for the contractor to be aware of the weather conditions that may ead to static build-up. Cold and dry winter weather is commonly associated with static build up, but if relative humidity is very low build up can also occur during hot, dry weather.

We note that this issue is not being discussed much in the roofing and waterproofing industry. However, please be aware that the issue of static-electric spark problems is mentioned by the manufacturers of adhesive application equipment, it is also referred to in OSHA bulletins, and has been mentioned in articles published in NRCA’s Professional Roofing magazine. Thorough descriptions of the problem as it relates to single-ply roofing, however, are lacking, and detailed solutions have not yet been presented.

Background Information:

This issue has come to our attention solely through reports from the field. To date, the information we have is mainly from three (3) different WSRCA Member Contractors working in the Western U.S. However, the popularity of insulated single-ply roof systems in the Western U.S. creates a growing potential for this problem to occur, and WSRCA wants to be sure it’s members are aware of the potential hazard and can then be better prepared to prevent the potential for fires on their projects, as well as be prepared to minimize the potential damage to persons, property and potential lack of calm-handling of the situation and/or potential injury to unaware roofing technicians.

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Information Bulletin 2018-LSI3: Roof-Mounted Solar Photovoltaic Systems

Posted By Western States Roofing Contractors Association, Monday, June 18, 2018

 

 

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Greetings to Members of Western States Roofing Contractors Association:

Executive Summary:
As the roof-mounted photovoltaics (PV) industry continues to expand with new products and attachment systems routinely getting introduced as the next best thing, it is imperative that roofing industry associations, such as the Western States Roofing Contractors Association (WSRCA) take a leading position and remain keenly involved to provide clear direction and recommendations for proper integration of PV systems with various roofing assemblies. WSRCA believes coordinated collaboration between the roofing and solar photovoltaic industries is paramount for shared success.

Within the collaborative environment, one of the main questions to ask as a PV system is first being considered is: "What is the condition of the existing roof system"? It may not be appropriate to install a PV system unless the anticipated life expectancies of the systems are coordinated with installation of a new roof system or a new roof covering (e.g., shingles, membrane, tile, etc.) as well. You do not want to install a new photovoltaic system over an old roofing system, only to realize a few years later that a new roof is needed and the PV system must be dismantled and removed in order to reroof. The warranty status of, and the remaining service life of an existing roof membrane system, and new Building Code requirements also need to be evaluated early in the PV system design process.

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WSRCA Informational & Alert Bulletin 2018-1W: Changes in ASTM Waterproofing Standards May Affect Contractors

Posted By WSRCA, Monday, April 30, 2018

Relatively significant developments within the industry’s waterproofing standards may potentially affect Western States Roofing Contractors Association (WSRCA) Member Contractors, as well as Member Designers of waterproofing systems, and perhaps some of our Manufacturer Members. Over the last decade or so ASTM’s Waterproofing Subcommittee D08.22 has made some rather significant advances in publishing several new standards. ASTM has also made changes to a number of existing waterproofing and waterproofing-related standards.

WSRCA members should be aware that if an ASTM standard is referenced in a project specification, the Contractor under contract for that work is typically required to comply with the requirements of the standard. It is also important to note that if current or future Codes governing a project reference an ASTM standard the design, materials, applications, and testing is to comply with the requirements of that standard. If an ASTM standard is referenced in the documents governing your project you are accountable for knowing the standard and performing construction according to the requirements of the referenced standard(s).

Some of the new standards, and changes to existing standards, if referenced by Project documents or amended into your state or locally adopted Code, could impact waterproofing contractors in ways that not everyone may be aware.

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ROOFING EDUCATION CONFERENCE

Posted By WSRCA, Tuesday, April 17, 2018



Western Roofing Expo 2018


Roofing Education Conference

WSRCA knows that you as a roofing or waterproofing contractor need to stay on top of the latest technical developments in the industry — and that's no easy feat! OSHA compliance, product issues, and best business practices are just a few of today's concerns. WSRCA has put together an amazing line-up of premium educational workshops for you - the roofing contractor - to succeed in today's competitive business environment. Earn CEU's, educate your company, and get a leg up on thecompetition!


Presented by: the Western States Roofing Contractors Association

ONLINE REGISTRATION SPONSORS


Follow WSRCA on Facebook, LinkedIn, Twitter, and Google +


   

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Did You Know? Members Can Receive Technical Advice From A Consulting Firm

Posted By Alec Ward, Western States Roofing Contractors Association, Friday, March 30, 2018

WSRCA Free Technical Advice

Did you know that as a WSRCA member, your membership provides you with complimentary technical advice from one of the most qualified professionals in the roofing and waterproofing industry? Whether you have a question about how to properly install, maintain or repair a specific roof system — or want advice on a current project, WSRCA members can contact our Technical Advisor for direct assistance.

To our members, technical advice is valued at $1,775 annually!*

* WSRCA conducted four qualitative research focus groups sessions throughout the western states (Phoenix, Los Angeles, Portland and the Bay Area) The dollar value listed is an average 'ROI' estimate by WSRCA members averaged over those sessions.

This is just one of the many ways WSRCA membership can take your company to new heights. Please contact the Western States office anytime to learn more about what we can do for you!
 
 
Regards,


Alec Ward Director of Membership
Western States Roofing Contractors Association
275 Tennant Avenue, Ste 106 - Morgan Hill, CA 95037
Local: 650-938-5441Toll Free: 800-725-0333

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FOLLOW-UP ALERT BULLETIN — Visible Knit-line Affected & Facer Irregularities in Rigid Polyisocyanurate Foam Roof Insulation

Posted By WSRCA Industry Issues Committee, Tuesday, March 27, 2018


FOLLOW-UP ALERT BULLETIN — No. 2018-II-1 — Visible Knit-line Affected & Facer Irregularities in Rigid Polyisocyanurate Foam Roof Insulation

WSRCA continues to monitor the observed quality of shipments of polyiso rigid foam insulation delivered to Members job sites over the last year or so, subsequent to WSRCA advising the roofing industry of concerns with knit-line attributed grooves and facer irregularities in the insulation. This Follow-up Bulletin is an addendum to our previous technical bulletin about this subject, and includes additional recommendations encouraging Roofing Contractors to be proactive in their approach to ordering and receiving rigid polyiso foam insulation. Following is a brief review of several key points communicated in the “2017 WSRCA Technical Bulletin - Knit-line & Facer Irregularities in Rigid Polyisocyanurate Foam Roof Insulation Bulletin No. 2017-II-1”.

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ROOF WARRANTIES – READING BEYOND THE DURATION TO COMPREHEND THE COVERAGE

Posted By Western States Roofing Contractors Association, Monday, March 12, 2018
Updated: Monday, March 12, 2018

 

By: Brian P. Chamberlain — Carlisle Construction Materials

 

INTRODUCTION

In today’s market we find significant focus from building owners on sustainable and durable roof installation. To accomplish this goal, building owners look to designers to specify durable products, supply qualified installers, and have material manufacturers offer long-term warranties. The first two conditions can be controlled and monitored to make sure that the installation is verified to have the proposed quality. The roofing warranty is looked upon by building owners and specifiers as a way to get a guarantee that these first two conditions are met. It’s very similar to an architect specifying a white membrane roof with the expectation, without any true consideration, that white membrane will help save energy associated to the operation of the building and in turn reduce the carbon footprint of the building. Unfortunately, without fully understanding how geography plays a major role in energy performance, the specifier may not design the roofing system to offer true energy performance and inadvertently increase other concerns. Studies have shown white membrane roofs need to be designed according to the building location geographically 1 . With the same consideration, it should be understood that warranties are tools to assist in selling of roofing manufacturer’s products and may not be an indicator of durability.

 

Samir K. Ibrahim, “Sustainable Roof Design: More than a Black-and-White Issue”, RCI - Building Envelope Technology Symposium, San Diego, CA, 2009

 

To understand this fully, we need to review how roofing material manufacturers promote warranties and then review the fine print of what they are covering within the language of the warranty.

 

DURABLE ROOFING ASSEMBLIES

The basic premise of a long-term warranty can be seen by how a manufacturer’s specification promotes sustainable assemblies. One of the first products we find typically required for longer term warranties is thicker membrane. Where shorter term warranties allow the use of thinner membrane such as 45-mil thick, longer term warranties are published with thicker membranes such as 90-mil thick. There is significant data to show that thicker membranes are superior to thinner membranes. For comparison, Figure 1 shows the results of a Federal Puncture Test with non-reinforced EPDM. The EPDM membrane with a 90-mil thickness has a 60% increase in puncture resistance over a 45-mil membrane.

 

Figure 1

 

Another indication of durability can be found by testing roofing materials within the Xenon Arc Weathering Test (ASTM G 155). In Figure 2 the results for a reinforced TPO membrane can be seen based on kJ/mÇ. The 80-mil thick reinforced TPO has 42% greater weatherability than a 45-mil thick reinforced TPO.

 

Figure 2

 

These results can be then compared to the proposed building location based on expected radiant exposure to determine the minimum design consideration. But just like building codes, to offer a durable long lasting assembly, the designer should go above the minimum. In most cases, the designer will find this parameter already required by the roofing materials manufacturer.

 

Figure 3

As membrane thickness is promoted by manufacturers through longer term warranties, other components of the roof assembly are promoted above the typical shorter term warranties. The splicing of EPDM membranes are specified to be either wider seams with tapes or factory applied tapes, while thermoplastic membrane assemblies promote overlayment of the seams with additional welded products. Longer term warranties promote factory manufactured flashings, such as pipe seals and premade curb flashings. Multiple layers and thickness of insulation are important to reduce energy costs in the long term and performance of the building. A single layer of insulation may assist in the initial sale of the assembly, but the typical gap left behind with energy loss could be significant over the long term as shown in Figure 4.

 

Figure 4

 

As technology improves products, they are promoted for longer term warranties. New insulation facers have been developed that offer moisture, mold, and wind uplift resistance. Figure 5 shows the typical uplift results between a fiber board, a standard black paper facer on polyisocyanurate, and a fiberglass coated facer on polyisocyanurate.

 

Figure 5

 

Manufacturers try to take into account foot traffic and unusual weather conditions that a roof assembly may experience over a long term warranty, so their roofing specifications include cover boards or higher compressive strength insulation to offer additional durability.

 

Besides warranties promoting thicker membranes, superior cover boards/insulations, and pre-fabricated accessories, there are incentives that can be included within the warranty, such as accidental puncture coverage, hail coverage, and reflective stability, if promoted enhancements by the manufacturer are specified. Some warranties will include other components, such as skylights, photovoltaic arrays, walking decks, and garden roof materials. In the case of the photovoltaic arrays, walking decks, and garden roofs, a membrane roof assembly’s components are specified to handle these additional uses of a roof area. If specified properly the manufacturer can include overburden removal and replacement within the warranty coverage, giving the owner the peace of mind that if a leak should occur, the investigation will not cost him anything additional.

 

 

WIND SPEED WARRANTY COVERAGE

Warranties also promote higher wind speed coverage and often incorporate cover boards, higher compressive strength insulation, and higher fastening density of the insulation to deal with long term performance. At times the specifier will find that the metal edging, which is the first line of defense against any wind storm, must be pre-manufactured and has been tested following the criteria within the ANSI/SPRI ES-1 and exceeds the International Building Code (IBC) standards. In higher wind locations, “Storm Strips” (a row of securement around the perimeter) might be suggested with the consideration to minimize storm damage.

 

For mechanically fastened assemblies, longer term warranties are available by specifying reduced spacing between rows of securement to increase uplift performance and fatigue on the roofing membrane. When special wind conditions are necessary for a warranty, an air barrier may be installed below the insulation on a steel deck to assist mitigating the interior pressure from the uplift, adding to the overall performance from wind.

 

WARRANTY LANGUAGE

This effort by a manufacturer to specify thicker membrane, better insulation, durable accessories, and incentives for additional coverage with a longer-term warranty increases the manufacturer’s reputation to the building owner in a positive manner. The building owner in turn assumes that the manufacturer’s warranty is an indicator of responsibility by the manufacturer and the relative life expectancy of the roof system. Unfortunately, warranties are used more as a marketing tool to assist in selling of roofing materials so even though a long-term warranty is preferable, the owner needs to review and understand what the warranty is actually offering as coverage.

 

After researching numerous published warranties and the phrases within, some warranties with equal duration do not match up with coverage. How many times have we heard, “Your 20-warranty requires additional components unlike your competitor? Isn’t all 20-year warranties the same?” Though the length of the warranty could be important, how each warranty is worded for coverage could be different allowing one roofing manufacturer more flexibility to deviate from the published specification by substituting lower performing products to have a more competitive advantage. To make sure the roofing installation has the same quality installation from either manufacturer, it becomes necessary for a building owner to understand what a warranty covers beyond the duration.

 

Once a building owner is convinced to read what is within a warranty, it can be difficult for the building owner to interpret the language. One of the reasons this is a problem is because warranties are written by the membrane manufacturer’s lawyer. The lawyer’s goal is to limit the liability of the membrane manufacturer. To make sense of what the building owner is actually receiving as coverage within a warranty, we need to focus on specific parts within a typical warranty.

 

Warranties are most often broken down into two parts. The first part is what the warranty covers which is typically referenced as the “roofing system”, defined as membrane, insulation, fasteners, flashing, and whatever additional components the manufacturer sells associated with the project. In my research I have found that the definition of “roofing system” can be altered. In one warranty the definition of the “roof system” was limited to just the roofing membrane without referring to any other associated purchased materials. Even though the warranty is titled Roof System Warranty the coverage only included the membrane, which is very similar to a material warranty. Though there is nothing wrong with a manufacturer defining a roofing system this way it can be misleading.

 

As mentioned, the first part also lists what else may be included under the coverage of the warranty. Sometimes a manufacturer does not sell a specific product required for the assembly, but is unwilling to lose the sale of their assembly, so they list these products on the warranty so as not to be excluded from the sale. This offers the flexibility necessary to keep the manufacturer in the prospect of winning the project. At the same time, they may list products that they do not cover, or the opposite simply not list such products at all, leaving the building owner with a potential hole in his expected coverage. An example would be a membrane manufacturer has the ability to sell all the components of an architecturally specified installation except for the asphalt required for insulation attachment. In this case, the manufacture may be willing to take the responsibility for the asphalt by listing this component on the warranty. If the manufacture does not want to cover the performance of the asphalt he may still offer the warranty, but list the asphalt as excluded from the coverage. Or the manufacturer will offer his warranty, but simply not mention the asphalt at all within the warrantable components. Again, none of the above is wrong, but it does reinforce the need for a building owner to read and understand the warranty coverage.

 

The second part is most often called “Terms, Condition, & Limitations” of the warranty. This section of the warranty can include numerous phrases that should be looked at closely to understand what is being offered. In this section, the membrane manufacturer offers details on how he will assist in paying for repairs. Some of the most common phrases have been “pro-rated”, “limited to original cost”, and “no-dollar limit” financial coverage. “Pro-rated” starts off with the original cost of the installation and then that amount is reduced a percentage each year based on the duration of the warranty. “Limited to original cost” limits the manufacturer’s financial responsibility to the initial cost excluding any inflation that could happen over the long term. “No-dollar limit” is the original cost with the inclusion of inflation. To see the difference between the two, Figure 6 shows an example of a 25-year pro-rated warranty versus a 20-year no-dollar limit warranty. Even though the duration of the longer warranty is 5 years, upon a catastrophic failure occurring at the 14th year the replacement cost to building owner is more than the original cost of the roof system. In this case, duration did not equal coverage.

 

Figure 6

 

In addition to how the warranty payment will be handled, the second section of the warranty includes the wind coverage. Wind speed coverage is a moving target. Historically, roofing system warranties did not offer this type of coverage. When it was thought to assist in the sales of the roofing system, warranties began to use words such as “Gale Force Winds”. The definition of this term can be found on Figure 7, a portion of the Beaufort Wind Scale.

 

Figure 7

 

Referring to Figure 7 one might be surprised to see that there are four different “Gale” type winds. The term “Gale Force Winds” referenced in some warranties is considered to be defined by the manufacturer as “Fresh Gale”, offering coverage up to 39-46 mph wind. Though the industry accepted this concept, owners demanded to know what the exact wind speed number might be, so some warranties started to actually list the wind speed as “not to exceed 55 mph”, which we can see on Figure 7 is “Strong Gale” wind coverage. When longer term warranties were introduced, they included an option of possible higher wind coverage, so 72 mph was offered, which is one mile per hour short of a hurricane.

 

With the introduction of wind coverage, building owners and specifiers have become confused about how this might relate to building codes 2. The bottom line is that they have no relationship to each other. The International Building Code does not require a wind warranty on roofs, only that they meet the allowable uplift pressures determined and calculated by using the ASCE 7. In this same respect other components such as structural walls, decking, etc. must also meet this calculated pressure, but none offer wind speed warranty coverage. Since this is the case, a warranty wind speed is not based on ASCE 7 or the ANSI/FM 4474 uplift rating test. Warranty wind speeds are typically based upon the manufacturer’s installation experience and the demands of the market.

 

Marty Gilson & Brian Chamberlain “Roofing Warranty Wind Speed Coverage versus Local Building Codes, Local Wind Speeds, and FM Global: Solving the Mystery,” Northern Illinois CSI Link, May 2007.

 

In an attempt to reduce misunderstanding roofing manufacturers can offer warranty wind speed coverage in miles per hour that equal the local wind speeds as published by the ASCE 7. It is important to remember that the ASCE 7 is referenced under the Performance or Quality Assurance section of a bidding specification, while the warranty wind speed needs to be listed in miles per hour in the Warranty section. If the requested wind speed coverage is not in the Warranty section, the contractor will bid the project at the minimum wind speed warrant coverage offer by the manufacturer. Typically when this is discovered, the roofing system has been installed and may no longer qualify for the higher wind speed warranty.

 

Values are nominal design 3-second gust wind speeds in miles per hour (m/s) at 33-ft (10m) above ground for Exposure “C” category

 

Figure 8

 

Though manufacturers include higher wind speed coverage if requested, the wording of their standard coverage can be worded to limit their liability, while at the same time offering the illusion that they are covering more. An example of this would be not listing the miles per hour in the warranty but using words like Gale Force Winds (39-46 mph). Another example would be calling out wind coverage up to “Beaufort Scale #8” (39-46 mph). In both cases, the miles per hour coverage is hidden by words and must be clarified.

 

Besides wording, where the wind speed is measured can be creative. Most warranties are measured at “Ground Wind Speed”, which is 33-ft or 10 meters from the ground surface, the same height at which airports measure wind speed. Some warranties have the phrase “Rooftop Wind Speed". The higher the roof area, the greater the wind speed, so if you are considering wind speed coverage, ground wind speed offers better coverage on a higher building. As an example, if the building is 30 to 40 feet high there is practically no difference in the coverage, but it can make a huge difference on high rise roof areas. In Figure 9, a 300 ft high roof area with a rooftop wind speed of 80 mph, the ground wind speed would be 55 mph, while a ground wind speed of 80 mph would actually cover winds up to 118 mph for the same building.

 

Figure 9

 

EXAMPLES OF WARRANTY LANGUAGE

The examples that follow are sample warranty wording that was discovered on different membrane manufacturer’s website samples.

 

In one manufacturer’s 30-year System Warranty, the financial liability of the manufacturer was “limited to the original cost”, so if the roof system cost $100,000 that would be the maximum the manufacturer would pay, not including inflation. In addition, it was listed in the warranty that the owner pays for two inspections every five years in addition to any cost for repairs required by the manufacturer. This warranty did not list any wind speed coverage, so we can assume that if the roof system is damaged by any wind greater than zero, it is not covered under the warranty. And finally this warranty was “non-transferable”. Though most schools and government buildings typically will never transfer ownership, a warehouse or office building could change hands within the 30-year duration of the warranty, leaving the new building owner with no coverage at all.

 

A 25-year warranty sample found on the web began by stating that this warranty only covered the membrane. If deterioration of the membrane was discovered, the manufacturer’s responsibility is to ship and replace “defective” membrane. The cost to the manufacturer was limited not to exceed the original cost of the membrane and shipping to the building site. Though it did offer wind coverage up to a full gale force winds (46 mph?) it was clear that it did not include any failure of the substrate under the membrane or failure of any other roofing components. How would wind cause the deterioration of the membrane? As a final note, the membrane manufacturer stated it would not cover the workmanship by the installer.

 

Another long term warranty (20-year) requires the building owner to schedule inspections with the manufacturer after 2, 5, 10, and 15 years at the owner’s expense. It did publish wind speed coverage less than 73 mph, which the Beaufort Wind Scale defines as being the lowest miles per hour for a hurricane. This warranty again was “nontransferable” and the coverage was “pro-rated”, so a $100,000 roof installation would loss coverage year after year.

 

One manufacturer published their warranty including similar language (“nontransferable” and “limited to the original cost”), but this 20-year warranty offer wind coverage with “gales excluded”. Returning back to the Beaufort Wind Scale, we see that gale force winds begin at 32 mph, so in reality, this warranty only offered coverage up to

31 mph.

 

Though there are many more warranty versions, this last one I offer is called a 20-year System Warranty and for the first 10 years has coverage is very similar to a “nodollar-limit” system warranty. But in the body of the warranty it states that after 10 years, the warranty becomes a “pro-rated” material warranty (labor not included) and lists the actual percentage of coverage. The Figure 10 below gives you an idea of financial assistance offered by the manufacturer, assuming the original installation cost $100,000.-.

 

20 Year Warranty % Coverage Cost of Installation $100,000.-

1st – 10th Year 100% Total System $100,000.-

11th Year 80% of Material $12,000.-

12th Year 60% of Material $9,000.-

13th Year 40% of Material $6,000.-

14th – 20th Year 30% of Material $4,500.-

 

 

PHRASES TO LOOK FOR

When assisting a building owner in the design of the roofing system to achieve the goal of durability, knowing the type of wording to look for in the warranty can be invaluable. Here are a few phrases that may be encountered:

 

• System Warranty: Where a Material Warranty will only cover the sheet good of the roofing system, a System Warranty typically is defined as covering all products installed offered by the manufacturer and includes the labor to install the referenced materials.

 

• Is the warranty transferable to a new owner upon the sale of the building or is there a limitation and stipulation that should be reviewed based on the owner’s plans for the future?

 

• Wording within the warranty may require the building owner to pay for periodic inspection by the roofing material manufacturer, including any costs associated to repairs found necessary during those inspections.

 

• A notation of maintenance required by the building owner, if not performed by the building owner could void the warranty. Though the above are some of the terms that should be reviewed closely below is some of the more favorable language that should be included.

 

• The warranty offers “full coverage” that includes labor to install and repair if necessary and material costs.

 

• “No Dollar Limit”, so if a catastrophic problem occurs and it is at the fault of the roof system, replacement of the roof system will cost the building owner nothing.

 

• The warranty should be “transferable” and there should be clarification of the cost and inspection requirements.

 

• Look for “wind coverage”, which should be listed in miles per hour and where the wind speed is measured should be specified.

 

• Depending on the building owner’s needs, possible additional coverage, such as hail, accidental puncture, or reflectivity should be included. This type of coverage is available but is not typically included in standard warranties. The building owner must have these needs referenced in the warranty section of the building specification.

 

In conclusion, the assemblies specified in association with a long term warranty do offer durable options for the building owner. They promote thicker membranes, stronger substrates, and better combined assemblies to match the length of the warranty and expectations of the building owner. Unfortunately, the published warranties need to be reviewed closely to make sure they match what is being offered.

 

One way a specifier could assist the building owner would be to review the warranty section of the proposed architectural specification to make sure some of favorable phrases listed earlier are incorporated in this section. Another would be to require a sample copy of the proposed warranty to be included with all bidding documents, so coverage can be reviewed along with cost. If anything within warranty wording seems amiss based on the building owner’s needs, clarification can be requested in writing from the manufacturer to clear up any confusion.

 

Keep in mind, if one manufacturer’s coverage is different than his competition, he can offer an assembly based on his warranty liability, the result could be a more cost competitive system with the building owner unaware of the potentially loss of warranty coverage. With this information, the specifier can guide the building owner away from using warranties as design criteria and focus on quality materials, proper assemblies, and verifiable workmanship.

 

 

References

Karen Warseck, “Roofing Warranties: Always Read the Fine Print,” Building Operating Management, February 2008.

 

Chuck Marvin, “Roof Warranties Moving Past Clichés,” Interface, April 2011.

 

Samir K. Ibrahim, “Inside the NDL,” PowerPoint Presentation, February 2006.

 

NRCA, “Roofing Warranties,” http://www.nrca.net/consumer/warranties.aspx

 

Republished with permission.

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