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Last Post 11/30/2006 10:58 AM by  dhouse
Glossary of Roofing Terminology
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Tom Toll
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11/26/2006 2:56 PM
    These terms and commentary could well help you with reporting and/or determining loss issues. I would suggest you save them in bookmarks or print to take with you in  folder.



    Glossary of Roofing Terms


    Architectural – A steep slope system that is used for visual impact or aesthetics and typically require a supporting deck with a minimum slope of 3:12. Architectural panels usually have low seam heights of 1 inch to 1-1/2” inches and do not use sealant between seams. Due to the low seam height and no sealant in the seams, architectural panels shed water but are not watertight and therefore require an underlayment below the panels to create a watertight system.

    Asymmetrical Panel – Asymmetrical panels have one leg of the standing seam panel different from the other so that these legs in adjacent panels may be joined without the use of a seam cap. These asymmetrical legs usually “snap” together in a male/female connection. Examples of Garland asymmetrical panels are R-Mer Loc and R-Mer Clad.

    BUR – The built-up roof is a multi-layer roof system that consist of multiple plies of reinforcements laid in a waterproofing bitumen. The alternating plies of reinforcement and waterproofing bitumen provide redundancy to the roof system. The reinforcements on a BUR are typically fiberglass felts, which provide strength to the BUR. The waterproofing bitumen can be asphalt or coal tar. The BUR is surfaced with gravel or a liquid applied coating.

    Cool Roofing - A cool roof is defined as a roof surface that has both high reflectivity and high emissivity. High reflectivity requires the surfacing material to reflect solar energy away from the surface. High emissivity requires radiating heat energy away from the surface. Roofs undergo significant expansion and contraction as they heat and cool throughout the day. Heat absorbed by the roof can also accelerate degradation by ultraviolet rays and water. A reflective roof can reduce the amount of thermal shock that occurs on the roof surface and make the roof last longer.

    Elongation – The ability of a membrane to be stretched and lengthened by force to accommodate movement. Roofing membranes have forces exerted on them from the building movement and the membrane must be able to accommodate these movements. If a 100 foot building expands by 3%, the walls would need to move 3 feet. This would increase the stresses on the building to the point of structural failure. The United States Army Corp of Engineers estimates that buildings move less than 1%.

    ENERGY STAR® - A registered trademark of the U.S. government. The ENERGY STAR® Program* represents a voluntary partnership between businesses and organizations and the federal government to promote energy efficiency and environmental activities. ENERGY STAR® labeled roof products are reflective and lower roof surface temperature by up to 100°F., decreasing the amount of heat transferred into a building. ENERGY STAR® labeled roof products are designed to help save money on utility bills and reduce energy waste. Ninety percent of the energy in the United States is generated by burning fossil fuels, which creates the air pollution associated with smog, acid rain, and global climate change. By reducing the amount of energy needed to cool buildings, ENERGY STAR® labeled roof products help to reduce the production of these air pollutants. Additionally, reflective roof products can help reduce the "heat island effect," a phenomenon in which cities can be 2 to 8°F. warmer than the surrounding countryside. Such heat islands occur, in large part, because many buildings and paved surfaces are designed with dark materials that absorb heat from the sun. This heat is released at night, causing the air temperature to remain high. The resulting elevated temperature leads to an increased demand for air conditioning in buildings, increased fuel use for vehicle air conditioning, increased levels of smog, and associated increased levels of heat-related and smog-related health problems. Installing reflective roofs helps reduce the heat island effect, decreasing the amount of smog in the air and benefiting the entire community.

    Fire Resistance – The ability of a roof top material to act as a barrier to the spread of fire and confine it to the area of origin. There are established test procedures for external fire exposure to classify roof systems into Class A, B, or C ratings. Underwriters Laboratories test method 790 established this procedure which ASTM adopted and named ASTM E-108. Therefore UL 790 and ASTM E-108 are the same test with different names. Factory Mutual and Warnock Hersey both use ASTM E-108 as the primary test for fire resistance.

    Flat Seam – Is a term used to describe when two metal panels are joined in a shingle fashion. The two panels can either be overlapped and fastened or folded and interlocked. Flat seam systems are made out of metal, which makes the roof durable, 100% recyclable and very low maintenance.

    Low Temperature Flexibility -The ability of a membrane to remain flexible (resist cracking) after it has been exposed to low temperatures. Roofing membranes encounter extreme weather conditions and resisting cracking at low temperatures is vital to the long-term performance of roofing membranes in colder climates. Low temperature flexibility is directly related to the amount of rubber incorporated in the membrane. Since the rubber modifier also increases UV protection, the better the low temperature flexibility, the greater UV protection a membrane will have. Therefore, low temperature flexibility is a vital criteria for warmer climates as well.

    Mechanical Finishes – Mechanical finishes are raised features on metal panels. These features are mesa patterns, pencil lines, or stucco embossing. Mechanical finishes help to reduce oil canning and strengthen the panels. Garland uses mechanical finishes to increase the performance of our metal roof systems, and also to add to their aesthetic appeal.

    Mechanically Curved – To create a curved profile in a metal panel, a machine is used to form the panel to a desired radius, hence the term, mechanically curved. This becomes important, because some manufacturers do not mechanically curve their panels; installers simply force straight panels to conform to the curve in a roof. This can cause many problems such as binding of standing seam panels on their clips, oil canning, and of course, failure. Garland has the ability to mechanically curve our symmetrical panels to the tightest radius available in the industry.

    Modified Bitumen – The modified bitumen roof system is a hybrid built-up roof. It has the benefits of the built in redundancy of the BUR, along with the added strength, flexibility and UV resistance of a modified membrane. The membrane consist of an asphalt and polymer blend which allow the asphalt to take on characteristics of the polymer. There are several surfacing option for this system which include a factory applied mineral surface, a gravel surface laid in bitumen or a liquid applied coating that is typically reflective in nature.

    Oil Canning – Oil canning is triggered by thermal expansion and contraction of metal roof panels and flashing. Oil canning can be seen as a rolling or washboard bending of a piece of metal. Causes of oil canning can be, binding of systems with limited thermal movement, and poor manufacturing techniques. To limit oil canning to a minimum, Garland designs our roofing systems with unlimited thermal movement, uses high quality roll forming equipment, and adds mechanical finishes to metal roof panels and accessories.

    Post Consumer Recycled Material - Post consumer recycled materials are those materials which have already served their initial purpose to a consumer and are then reclaimed rather than being discarded in traditional landfills. Common post consumer recycled materials include tires, aluminum cans, newspapers, plastic bottles and glass. Innovative companies are finding new ways to break down these materials and incorporate them into their processes. Post consumer waste is generally recognized as being more environmentally friendly because once materials reach the consumer they are more likely to end up in landfills.

    Post Industrial Recycled Material - Post industrial recycled materials are those materials that have been recovered or otherwise diverted from the waste stream during the manufacturing process. This does not include used, reconditioned or remanufactured components.

    Scrim – The reinforcing fabric that acts as a carrier for the polymer modified bitumen. The scrim contributes to performance characteristics of the finished product that include tensile strength, puncture resistance and fire resistance. The two primary fabrics for scrim include fiberglass and polyester. There is also a combination scrim which incorporates both of these fabrics.

    Standing Seam – Is a term used to describe the adjoining of two metal panels together with an upturned portion of the metal. The two panels are held together with concealed clips. The joinery raises the seam above the drainage plain. Standing seam systems are made out of metal, which makes the roof durable, 100% recyclable and very low maintenance.

    Structural – A low slope system that can support their own weight without a deck. Structural panels usually have high seams 1-3/4” to 3” and can handle slopes as low as 1/4:12. The panels are watertight and can span long distances. Since a deck is usually not required a structural system can end up being a lower cost alternative than an architectural panel with a supporting roof deck.

    Symmetrical Panel – A symmetrical panel design has both legs of the standing seam panel identical in size and shape. This is typically found in panel system where a cap is used to seam the panels together. Benefits of a symmetrical panel are easy replacement, and tighter curving radiuses. Examples of Garland symmetrical panels are our structural system, R-Mer Span, and our architectural system, R-Mer Seam. Due to its symmetrical design with a seam cap, R-Mer Span has the highest rated uplift pressures resistance in the industry.

    Tensile Strength – The maximum force a material can bear without tearing apart. Roofing membranes should have sufficient tensile strengths to resist the severe stresses caused by internal and external forces imposed on it. Thermal shock, caused by sudden heating or cooling of a membrane, causes stress that a roofing membrane must be able to withstand. The greater the tensile strength a membrane has, the greater resistance it will have to splitting, breaking or tearing throughout its life. Many roofing publications, including the NRCA’s Roofing and Waterproofing Manual and Dr. H.O. Laaly’s The Science and Technology of Traditional and Modern Roofing Systems, confirm that superior tensile strength has a direct correlation to the long-term performance of a membrane.

    Thermal Bridging – A condition where heat or cold can be conducted through a metal fastener or opening from the underside of the roof assembly to the outside of a roof surface. Properly designed roof assemblies will eliminate thermal bridging from occurring.

    Unlimited Thermal Movement – All materials experience the stresses related to heating and cooling of the roof surface. In some cases, temperatures of a roof surface can vary by up to 200 degrees F throughout the course of a day. The term “unlimited thermal movement” describes designing a roof system to accommodate all of the expansion and contraction that a roof may experience throughout a 200 degree cycle. With a metal roof, this movement can be in the order of several inches. The Garland Standing Seam, one-piece clip design allows the metal roof panels to move freely through an unlimited range of expansion and contraction. Garland’s flat seam metal roof system, R-Mer Lite is also designed with the unlimited thermal movement concept.

    UV Resistance – The ability of a roof top material to prevent degradation caused by exposure to Ultraviolet rays. Heat and UV are two primary causes of premature roof failure. UV rays cause the oils in a roofing membrane to dry out. These oils provide pliability and leads to the membrane cracking when they are dried out. The addition of unique polymer blends provides protection to the membrane from cracking by maintaining the membrane’s pliability. The resistance to UV degradation prevents membrane cracking which prolongs the waterproofing life of the membrane.

    Wind Uplift –A wind uplift rating is not the miles per hour of wind speed a roof system can withstand, but rather, the negative pressure (pounds per square foot) that occurs when the inside air pressure of a building is greater than the air pressure outside the building. As wind passes over a building, there is a decrease in external air pressure on roof and some down wind surfaces. As this external decrease in air pressure occurs, there is a corresponding increase in air pressure differential between the inside and the outside of the building. As the internal air pressure tries to equalize itself with the external pressure, the resulting force, identified as wind uplift forces, attempts to lift the roof off the building. Most parts of North America require a 1-60 or 1-90 uplift resistance. Coastal regions and high wind areas may require additional uplift resistance.
    Success is not final, failure is not fatal: it is the courage to continue that counts.
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    dhouse
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    11/30/2006 10:58 AM
    Thanks Mr. Toll.
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