By: Brian P. Chamberlain — Carlisle Construction Materials
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.
1 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.
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.
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.
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.
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.
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.
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.
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.
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.
2 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
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.
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
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.
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.