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Johns Manville
Commerical Industrial Roofing Systems\Roof Insulations
Roof Insulations - Page 1
Commerical Industrial Roofing Systems\Roof Insulations
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Roof Insulations |
Contents Section I: Product Information Product, Design and Installation Considerations
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Page 9-1 9-1 |
Fesco Board 9.1 Product Information
Effective roof insulation helps lower overall energy consumption, reduces HVAC equipment requirements, and brings about improved comfort for the occupants of a building.
JM provides these benefits with a full line of high performance insulations for built-up and modified bitumen roofs. The section that follows reviews the JM product line. Prior to product selection, it is recommended that the product performance, design and installation concepts of the roofing system be considered to ensure the correct product selection.
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This Paper Recycling Symbol indicates that JM has joined other manufacturers of commercial and consumer goods throughout the United States in the utilization of recyclable materials. |
In the Fesco products that bear this symbol, JM has incorporated recycled cellulose in the manufacturing process. The minimum recycled content is 25% by weight.
9.2 Guarantees
It is also important to protect a roofing system with a guarantee of performance. JM offers a wide variety of Roofing System Guarantees, including many 20-year No-Dollar-Limit (NDL) specifications which are available from NDL Approved Contractors only. Check with a JM Technical Service Specialist for the names of approved NDL Contractors in your area and details on NDL guarantees.
9.3 Product Considerations
9.3.1 Insulation Characteristics. Roof insulation performs two basic functions in any roof system. It is the primary thermal barrier for the top surface of the building envelope, and it serves as a base for the roofing system. In order to perform these two functions successfully, any roof insulation should have the following characteristics:
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Sufficient thermal resistance ("R" Value) to meet the designer’s needs. |
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Resistance to indentation, compression and crushing during installation of the roof membrane and during periodic maintenance, once the roof is completed. |
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Rigidity to support the roof membrane and to span the rib openings of metal roof decks. |
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Resistance to moisture absorption. |
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Dimensional stability. |
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Compatibility with common roofing systems and attachment techniques. |
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Resistance to wind uplift, and pull-through of mechanical fasteners. |
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Acceptability by Underwriters Laboratories, Factory Mutual and Code Agencies. |
9.4 Design Considerations
9.4.1 Drainage. Proper drainage must be provided on all roof systems. Standing or ponded water hastens the deterioration of any roof system since the water can work its way through laps or any minor application flaw in the membrane. For information on tapered insulation systems, see page 9-15.
9.4.2 Double Insulation Layers. Installing roof insulation in multiple layers provides the designer with improved thermal performance. It also contributes to the overall performance of the roof system for the following reasons:
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Recent studies indicate that as much as 8% of the thermal efficiency of the insulation can be lost through the insulation joints and exposed insulation fasteners of single layer installations. Insulation joints that are staggered in multiple layer installations block the flow of heat. |
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Multiple layer insulation installation reduces the stress accumulation of a thick, single insulation joint and distributes the stress more evenly over the multiple, thinner insulation joints. |
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The bottom side of the membrane is protected from physical damage from insulation plates and fasteners by the second layer of insulation. |
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Roof decks are stiffened. |