Hence, modification of the details to delete propriety names will typically be necessary. Most EPDM sheets are black, although white sheets are available. However, the IBC also includes provisions pertaining to general serviceability, such as minimum roof slope. The block spline is a thin and narrow SIP assembly that is inserted into recesses in the foam along the panel edges. Greater emphasis on the importance of controlling airtightness. Non-rigid insulations are typically used in attic spaces and in pre-engineered buildings. If slate is specified, a very durable underlayment is recommended, so that it does not prematurely degrade. To avoid the pecking, granules are commonly broadcast into the coating while it is wet. Since the 1970s, many warranties have become marketing tools rather than true reflections of demonstrated roof system performance. HCFC had a much lower ozone depletion potential than CFC. It is therefore incumbent upon designers and contractors to be cautious when specifying and installing new products and system designs. Figure 5: Example of SIPs used for roof panels showing seeping of sealant at SIP joint, Breckenridge, CO.Photo Credit: CW Associates, PLLC, (CWA Architecture), Figure 6: Example of SIPs used for wall and roof panels showing seeping of sealant at SIP joints, Winter Park, CO.Photo Credit: CW Associates, PLLC, (CWA Architecture). Detail shop drawings shall be provided by the manufacturer for coordination and to address the General Detail Principles as mentioned above. The base sheet should be adhered when decking is non-nailable. To date, the tallest structure constructed exclusively of SIPs is four stories. If the roof membrane is monolithic (i.e., a membrane roof) it serves as an air retarder. Four plies of felt are recommended (if a nailed base sheet is installed, four plies are recommended in addition to the base sheet). In addition, all panel joints, openings around windows and doors, and other chases should be properly sealed and/or flashed to prevent moisture infiltration. These details should be considered as only a starting point in creating project specific details. After completion of all building construction, but before occupancy, consideration should be given to NDE of the roof to check for excessive moisture within the roof system. Solvent-based adhesive and hot asphalt disintegrate EPS. This PMR has of two layers of XPS. Based on Spline, Block Spline, or Cam lock panel joint connections. For example, the IBC has construction document requirements in sections 107 and 1603 (2012 edition). We wantâ¦â For example, if a 40-year service life is assumed, but the roof fails after 15 years, the true roofing costs will be much higher than calculated. (See Figures 4, 5, & 6). Plywood and oriented strand board are occasionally used if required for high-wind speed uplift warranties. Minor imperfections may be accommodated with careful, skilled installation. Finally, ballasted systems should not be used in high wind or hurricane areas because the ballast tends to become airborne, causing massive damage to adjacent buildings. Complete voiding of the warranty if an "unapproved" roofer makes even a small modification. PUR and PIR panels can be made up to 8-1/4 inches thick. There are six primary methods for securing single-ply roofing systems to the roof deck or other substrate: 1. Around the early 2000s, a variety of self-adhering single-ply membranes emerged, along with renewed interest in self-adhering, modified bitumen membranes. It is better to avoid the situation all together and use rigid insulation on top of the deck with a water-resistant air and vapor retarder membrane below and cover board or sheathing above. Because water vapor can migrate through the foam, the aggregate surfacing option should not be specified in situations where the annual net vapor flow is downwards. Shop Drawing Coordination: Require SIP wall installation shop drawings showing all adjacent construction and related work, including flashings, gaskets, sealants, structural components in the SIP's, attachments, and indicate sequencing of the work. Figure 10. 4) Is the roof accessible for repair? Also, field research has demonstrated that they have exceptionally good wind resistance. Without a warranty, the Owner might have to pursue legal action to obtain relief. Some early formulations of PVC suffered from plasticizer leaching out over time and experienced catastrophic failures. These systems are typically not recommended due to shifting of the insulation board that commonly occurs and the difficulty in detecting leak locations due to the free flow of water underneath. Allowable deflection tolerances set by the manufacture of the panels and sealants should be consulted when designing the foundation. For example, in areas where deep accumulation of slush under snow is anticipated, the height of base flashings should be increased above the typical 8" (200 mm). In other instances, there has been a move to water-based rather than solvent-based products. ", Structural Insulated Panel Association, ". Although tapes offer performance advantages over liquid-applied adhesives, the contractor still needs to exercise care in cleaning the EPDM prior to tape application, priming the EPDM and diligently executing the seam work as recommended by the manufacturer. The fate of many prematurely failed roofs is often set by poorly prepared documents (Figure 14). The following are examples of changes to standard warranties that should be considered for all projects: Figure 14. Otherwise the secondary layer could easily detach. Built-up roof membranes are composed of alternating layers of bitumen (either asphalt or rarely coal tar) and reinforcement sheets (felts). Full-length panels eliminate this problem area. Another method of application uses fleece-backed EPDM, which is set in low-rise sprayed polyurethane foam adhesive. PVDF is typically specified since if offers a large range of colors and is extremely resistant to color change over time. However, EPDM is susceptible to swelling when exposed to aromatic, halogenated, and aliphatic solvents, and animal and vegetable oils such as those exhausted from kitchens. It is recommended that the guidance should be included in the contract drawings or referenced in the specifications). Cover boards should be placed over the primary thermal insulation (typically one of the plastic foam insulations) in order to provide enhanced physical characteristics, such as improved fire and compressive resistance, prevention of delamination of facers due to traffic on the roof, provision of improved wind uplift resistance, and to avoid blistering or avoid a compatibility problem. The physical characteristics of asphalt are actually not well suited to roofing; they are not UV stable, get brittle with age and cold, crack, alligator, and otherwise degrade relatively quickly. It is more difficult to achieve a reliable and long-lasting watertight system on a low-slope roof with metal than it is with the other low-slope membrane materials. Write daily reports and give them expeditiously to the contractor (and to the roofing designer if the observer is not an employee of the structural firm that designed the roof). Figure 7. If specification of a warranty is being considered, review the warranty section of NRCA's Low-Slope Roofing Materials Guide (or the Steep-Slope Roofing Materials Guide). Interior and exterior temperature/humidity parameters. Structural panels may be specified if a solid deck is provided. Therefore for example, a system that requires re-coating more frequently than every 15 years is not recommended. They are also highly dependent on the reinforcement within the sheet. Mesh reinforced elastomeric coating installation. The following should be undertaken at the conference: Review the salient features of the specifications, including schedule, product delivery, storage, and handling, roof loading, weather conditions, unique or critical items specified in Part 3âExecution of the specifications, and protection of the completed roofing from work of other trades. Vapor retarders may also be required to prevent condensation under white or light-colored membranes (cool roofs) in cold climates because the temperatures of such membranes may be so low that even occupancies with low or average interior humidity can cause condensation in such circumstances. If fastener pullout tests were specified, verify that the results are acceptable. Hand-held, hot-air welders are used to weld seams at flashings and penetrations. The NRCA has a section and details for this type of roofing in The NRCA Roofing Manual: Membrane Roof Systems. Figure 12. After a suitable roof system has been selected, appropriate specifications and drawings need to be prepared to help ensure that the roof designer's design concept is understood and executed by a professional roofing contractor. However, because there is only one layer of waterproofing, they do not offer the reliability of multiple layers. Underwriters Laboratory (UL) and FM Global have also developed a number of standards pertaining to test methods. Low slope roofing is sometimes accomplished by using a Plaza Deck or an Extensive Vegetative Roofs. Because of its permeability, the ECH manufacturer recommends placing ECH over an EPDM membrane. The surface spline connection and the block spline connection result in a continuous foam core across the panels, eliminating air infiltration at the joints. It was not until introduction of the third generation blowing agent, hydrofluorocarbon (HFC) that a blowing agent with a zero ozone depletion rating was available. When the deck is used as an air barrier, deck penetrations such as plumbing vents should be sealed, and the deck should be sealed at parapets. EPDM sheets are resistant to the effects of UV radiation and are very durable. Verify SIP span and structural limit requirements. Along with new choices of membrane materials, plastic foam roof insulations also emerged in the 1970s. Low voltage electronic leak detection may be employed continuously to monitor roofs to warn of leaks before they migrate to the building interior. The foam core is generally one of the following: expanded polystyrene (EPS), extruded polystyrene (XPS), and polyurethane foam (PUR). ASTM standard D312 is the product standard for asphalt used in roofing. The following membranes are typically used on low-slope roofs, but may also be used on steep-slope roofs. Insecticides are added to the panels during manufacturing or later on site. However, slate is heavy and very expensive. An additional secondary seal air seal of tape or gasket should be provided at the interior face of the panel, especially in cold climates. Furthermore, they do not ensure that damage caused by hail or wind, or another type of damage will not occur. APP MB membranes can also be used in a protected membrane roof (PMR) configuration, also called inverted roof membrane assembly (IRMA). Each sheathing material and foam type has its benefits and drawbacks. This section addresses metal panels suitable for use on slopes of 3:12 (25 percent) and less. With the wider sheets, fewer rows of membrane fasteners are required and there are fewer time-consuming field seams to fabricate. Atactic polypropylene (APP): APP polymer is blended with asphalt and fillers. The presence of a vapor retarder can make it difficult to find leaks, as they can carry water great distances from the source of the leak. Openings can occur anywhere within the panel, including at the edges and corners. The membrane is constructed by spraying a two-part liquid onto a substrate. The low-density product is relatively inexpensive. To avoid mistakes such as this, this type of detail should be discussed at the pre-roofing conference, as it involves coordination between the plumbing and roofing contractors. In many instances, the reinforcing fibers and products that were initially introduced to replace asbestos offered very poor performance. (See Figures 1, 12 & 13). The agenda for both conferences is generally the same. Another example is a penetration detail that the foreman desires to flash differently than detailed. SA membranes self-seal around nails and other penetrations, can be exposed to sunlight for extended periods, and aggressively sticks to just about any material. KEE sheets are similar to PVC. It is preferable to select a system that can be installed by contractors who have an office relatively close to the project site. SIPA recently completed Technical Bulletin 008, Wall Aspect Ratios for SIPs, which provides the necessary data for compliance with the IRC and IBC requirements. This section provides a brief overview of the primary roof deck, air barrier, vapor retarder, insulation, and roof covering materials used in the U.S. For further information on these materials, refer to The NRCA Roofing Manual (published by the National Roofing Contractors Association).
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