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). The bottom surface has a release paper to keep the sheet from bonding to itself while rolled. They do not provide for proactive replacement if a roof is clearly failing and degrading but still not leaking. Components include durable flashing materials, structural components in the SIP panel, sealants, foam, tape, gaskets, fasteners, etc. Housewrap should not be used for a vapor retarder because it has inadequate vapor flow resistance. 3. TiteBond doesn’t recommend it’s use in structural applications, so if you have some roof beams to glue, use something else (like polyurethane or epoxy, for example). Four plies of felt are recommended (if a nailed base sheet is installed, four plies are recommended in addition to the base sheet). Cold fluid adhesives may have high VOC content. The insulation is protected from ultraviolet (UV) radiation and wind blow-off by concrete pavers or large aggregate. During construction contract administration, the roof designer or the entity responsible for construction contract administration has several important tasks. With an understanding of the available system options, consideration of the following technical and non-technical criteria can lead to the selection of the most appropriate system and details for a project. (Morley), Today, SIPs are prefabricated building components for use as walls, floors, roofs, and foundations. The following tables outline the benefits and drawbacks of the most common sheathing and foam types. As there may be issues with a fleece-backed system set in asphalt, designers are advised to consult with the manufacturers before specifying or detailing fleece backed system with asphalt. The details, graphics, and related information shown in the details are intended to illustrate basic design concepts and principles only and should be considered collectively with the appropriate narrative sections of the Whole Building design Guide (WBDG). On slopes of 1:12 (8 percent) or less, it is recommended that mechanically seamed panels be specified. Mechanically attached systems may not be suitable for buildings in high wind zones. Foam is applied in any gaps resulting after the installation of electrical wiring. It is widely used in low-slope roof systems. Hence, rather than specify a modified bitumen membrane with a field-applied coating, a granule or foil-surfaced membrane is preferable to avoid future re-coating costs (see Figure 12). The service life can have a dramatic impact on the LCC analysis. With EPS and XPS foam, the assembly is pressure laminated together. When installed on low-slopes (particularly slopes approaching 1/2:12 (4 percent) or less) a metal panel system needs to provide water resistance all across the roof surface. For large slate and tile roofs, if there is sufficient cost savings, both corner, perimeter and field resistances can be specified.). Of course, it is the building owner who experiences the leak and suffers the bulk of the damages from this risk evaluation. It is therefore incumbent upon designers and contractors to be cautious when specifying and installing new products and system designs. For these reasons, fully adhered systems or mechanically attached systems are preferred over loose-laid. Besides readily lending itself to complex roof shapes, SPF roofs are exceptionally thermally efficient, since they do not have mechanical fasteners or insulation board joints, which create thermal bridges. Fumes are particularly noxious to many people and should be avoided on occupied buildings. Some manufacturers offer XPS made from recycled XPS. Veracity of manufacturer's training programs for roofing installers. At parapet and roof-to-wall details, the low-point of the roof should be drawn and a dashed line placed at the high point if the roof elevation varies. See the section on Sprayed Polyurethane Foam for more information on this type. Although the Data Sheets are not "standards" because they did not go through a consensus development process, they have essentially become de facto standards: Functional / Operational—Ensure Appropriate Product/Systems Integration, Unified Facilities Criteria (UFC) on RoofingUnified Facilities Guide Specifications (UFGS), See appropriate sections under applicable guide specifications: VA Guide Specifications, DRAFT Federal Guide for Green Construction Specifications, MasterSpec®. These newer systems included modified bitumens, single-plies, sprayed polyurethane foam, metal panels, and reinforced liquid-applied roof membranes. The coating is weathering away as expected. (See Figures 4, 5, & 6). The goal of 'Whole Building' Design is to create a successful high-performance building by applying an integrated design and team approach to the project during the planning and programming phases. Standing-seam metal roofs are often used for their appearance. The following elements are critical in communicating project requirements to the contractor: To produce good specifications, the roof designer should first acquire a suitable guide specification. Owner's expectation for warranty coverage: will the owner expect and pay for a warranty that extends all the way to the predicted wind speed. Provide exterior roof and wall ventilation/drainage plane systems. Acoustics: SIPs insulate against high frequency noise better than low frequency noise. Both one- and two-part coatings are available. Note: APP MB sheets are also available with a factory-applied adhesive on the underside of the sheet, which permit them to be self-adhering. There are three categories of roof insulation: rigid board, non-rigid (batt, blanket, or loose fiber) and sprayed polyurethane foam. When involved with landscaped roofs, consider warranties that cover the cost of removing and replacing the overburden of the landscaping to access the roof. A warranty may also enhance the likelihood that a professional contractor will install a roof. For most roofs, several different types of systems could serve quite well. Also, the following Unified Facilities Guide Specifications (UFGS) are available: Roof decks: 03 31 00.00 10 (cast-in-place concrete), 03 51 13 (pre-cast concrete), 05 30 00 (steel), 06 10 00 (wood) Figure 1: Example of SIPs used as infill with a structural steel frame, Silvis School, Illinois.Photo Credit: Steven Schaefer Associates, Inc. Some rooftop equipment and some materials, such as pallets of pavers, are very heavy. Liquid-applied membrane roof systems typically are reinforced with polyester reinforcing fabric or fleece. In other cases, perhaps two or three factors may be nearly equally as likely to end the roof's life. Recognize regional climatic and geographical factors. These initial panels were used to build test homes that were disassembled and tested after thirty years to reveal that the panels retained their initial strength values. Coal tar pitch is suspected to be carcinogenic and most owners and designers avoid it for that reason, in spite of the excellent performance characteristics. Figure 4: SIP ridge and gable end tape/gasket seal. Styrene-Ethylene-Butylene-Styrene (SEBS): SEBS polymer is blended with asphalt in a factory. The seam is sealed with sealant tape or sealant in case it becomes inundated with water backed up by an ice dam or driven by wind. Corrective action should be taken with this type of error. Asphalt Shingles: 07 31 13 Recent energy code standards require an air tight building envelope, and a SIPs building with properly sealed panel joints is inherently airtight. The observer should: Be provided with portions of the contract documents related to the roof. Openings can occur anywhere within the panel, including at the edges and corners. For example, the IBC has construction document requirements in sections 107 and 1603 (2012 edition). Products covered by some ASTM standards have a substantial range in physical properties. Tape applied seams should be used. However, there are a few design and application guides: There are a few ANSI standards that pertain to roof systems, including: Wind Loads: ASCE/SEI 7-10 Minimum Design Loads For Buildings and Other Structures (this standard is often referred to by local code requirements and regulations). As of 2005, EPDM enjoys the largest market share of the single-plies in service in North America. The designer also needs to possess adequate roof design knowledge in order to properly utilize adopted details, such as the NRCA details. ", "Thermoplastic Composite Structural Insulated Panels (CSIPS) for Disaster Mitigation Construction. It is formulated from polypropylene, polyethylene or other olefins. The panel foam can be recessed to accept 2x lumber headers. Accelerated aging testing is of limited help, as it has not progressed to the point where credible estimates of service life prediction can be made. Polystyrene: There are two types of polystyrene insulation: expanded polystyrene (sometimes referred to as EPS or bead-board) and extruded polystyrene (sometimes referred to as XPS). Fully Adhered: The membrane is adhered in a continuous layer of adhesive, preferably to a insulation cover board. Primary membrane types in this category are: Polyvinyl chloride (PVC): PVC membranes are among the oldest single-plies still available. Mineral wool is also available in configurations suitable for roofing; it has a higher compressive strength than fiberglass. This system should only be used over an air-impermeable roof deck or over an air barrier. With PUR and PIR, the liquid foam is injected and cured under high pressure. Loose-Laid Air-pressure Equalization System: The membrane is fully adhered around the roof perimeter, but elsewhere the membrane is only loose-laid. It is preferable to select a system that can be installed by contractors who have an office relatively close to the project site. Although the total time for manufacturing and assembling a SIPs structure is less than that of a framed structure, more time is required in planning. To compensate for minor air leakage between the membrane and the deck/air barrier, air-pressure equalization valves are installed at prescribed intervals. To be effective, vapor retarders must be airtight at all penetrations. The mixture is then factory fabricated into either 3 feet or 1-meter wide rolls. Consider using maximum 4 by 4 foot boards to reduce the gaps caused by shrinkage of the insulation. For re-roofs: there are many more criteria. When a BUR is installed over polyisocyanurate, a suitable cover board should be installed over the polyisocyanurate. All lap seams shall be fabricated with 6-in. Prior to 1990, asbestos fibers were used in a variety of products, including asbestos-reinforced base flashings for built-up roofs, asbestos-fibrated roof coatings and asphalt roof cements and cement-asbestos shingles. Figure 16. 4. A reinforced liquid-applied roof membrane is considered by NRCA to be a roof system. The Details section discusses and presents various details. Structural engineer to do wind uplift analysis per ASCE 7. A manufacturer's warranty establishes a direct contractual relationship between the building owner and manufacturer. Polystyrene is one of the plastic foam insulations and should be used with caution where hot roofing materials are employed. The nailer therefore lifted and caused a progressive peeling failure of the roof membrane. Verify SIP span and structural limit requirements. If a PMR system is specified, a slip-sheet recommended by the membrane manufacturer should be placed between the membrane and the XPS to prevent the insulation boards from bonding to the membrane. Hydrostatic: With hydrostatic systems the panels have standing seams, which raise the joint between the panels above the water line. The two types have distinctly different properties. Generally, when a building least dimension is 75' or less, a steep-sloped system should be selected over a low-sloped system. If the field observer is not an employee of the architect, also establish a line of communication between the observer and the architect, and establish the extent of the authority that the observer has with respect to interpretation of the contract documents and the handling of unforeseen conditions. Delete warranty language that takes away the Owner's rights, Delete warranty language that excludes other rights and remedies, Delete warranty language that sets a maximum dollar limit, Delete or modify the unfavorable items listed above in "Warranty Limitations. Only one manufacturer produces it in North America. Mineral wool: R-4 (approximate) is not seen very often in low slope roofs, except as a replacement for fiberglass insulation between roof rafters in residential construction. 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 3—Execution of the specifications, and protection of the completed roofing from work of other trades.
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