ROOF DECK SECUREMENT AND ABOVE-DECK ROOF COMPONENTS

Transcription

1 FM Global Property Loss Prevention Data Sheets 1-29 September 2010 Page1of40 ROOF DECK SECUREMENT AND ABOVE-DECK ROOF COMPONENTS Note to Insureds of Factory Mutual Insurance Company: Contact the local FM Global office before beginning any roofing work. Table of Contents Page 1.0 SCOPE Changes LOSS PREVENTION RECOMMENDATIONS Introduction Construction and Location General Vapor Retarders (Barriers)Design and Installation Recommendations Roof Insulation Insulation and Roof Cover Fasteners Recover and Reroof ConstructionDesign and Installation Recommendations Structural Concrete, FM Approved Fiber Reinforced Cement and Lightweight Insulating Concrete (LWIC) Decks: Design and Installation Recommendations Single-Ply Membrane Covers and Multi-Ply covers with Mechanically Attached Base Sheets Asphalt and BUR Installation Recommendations Roof Covers Adhered to Mechanically Attached Base SheetsFastener Installation Recommendations Liquid Applied Roof CoversInstallation Recommendations Mechanically Fastened Base Sheet Assemblies Over Wood DecksDesign and Installation Recommendations Roof Deck Span and Securement for Wind Loads Lightweight Insulating Concrete Roof Decks Cementitious Wood Fiber Roof Deck Recommendations Lumber and Plywood Deck Structural Concrete Roof Deck Recommendations Torch Application of Modified Bitumen Roof Covers Field Wind Uplift Tests Cold-Process Adhesives Fiberglass Reinforced Plastic (FRP) Roof Deck SUPPORT FOR RECOMMENDATIONS Supplemental Information Class 1 and 2 Roof Decks Wind Uplift Resistance, Non-Ballasted Roof Covers Wind Uplift Resistance, Ballasted Systems Compatibility With Substrate External Combustibility Recover Construction Wind Uplift Wind Damage Inferior Construction Steel Deck No part of this document may be reproduced, stored in a retrieval system, or transmitted, in whole or in part, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission of Factory Mutual Insurance Company.

2 Page 2 FM Global Property Loss Prevention Data Sheets 4.0 REFERENCES FM Global Others APPENDIX A GLOSSARY OF TERMS APPENDIX B DOCUMENT REVISION HISTORY List of Figures Fig. 1. Hailstorm hazard map for United States (areas between dashed lines subject to severe hailstorms and need an SH hail rated roof) Fig. 2. Insulation and vapor barrier mechanically fastened to steel deck Fig. 3. Fastener placement 2 4 ft ( m) boards Fig. 4. Fastener placement 3 4 ft ( m) boards Fig. 5. Fastener placement 4 4 ft ( m) boards Fig. 6. Fastener placement 4 8 ft ( m) boards Fig. 7. Alternate corner increase for mechanically attached single-ply membranes Fig. 8. Fastener layout for 36 in. (914 mm) wide base sheet Fig. 9a. Side lap fastening: interlocking seam Fig. 9b. Side lap fastening: overlap seam Fig. 10. Two deck fasteners per support, one into each bar joist top flange Fig. 11. Torch application of upper ply to a mechanically fastened base sheet Note adhesive pooling at the leading edge of the roll Fig. 12a/12b. 4 4 ft ( m) insulation boards secured with nine fasteners per board List of Tables Table 1. Recommended Rating of Field, Perimeter, and Corner Areas (Zones 1, 2, and 3) for Enclosed Buildings... 5 Table 2. Weight Needed of No. 3 Round Stone Ballast, Parapet 36 in. (914 mm) Table 3. Weight Needed of No. 3 Round Stone Ballast, Parapet > 36 in. (914 mm) Table 4. Weight Needed of Paver Blocksnot T&G, Beveled or Strapped to Each Other, Parapet 36 in. (914 mm) Table 5. Weight Needed of Paver Blocksnot T&G, Beveled or Strapped to Each Other, Parapet > 36 in. (914 mm) Table 6. Weight Needed of Paver BlocksT&G, Beveled or Strapped to Each Other, Parapet 36 in. (914 mm) Table 7. Weight Needed of Paver BlocksT&G Beveled or Strapped to Each Other, Parapet > 36 in. (914 mm) Table 8. Base Sheet Fastener Coverage for Non-FM Approved Combinations, ft 2 per Fastener Table 9. Standard 36 in. (0.9 m) Base Sheet Fastening (Non-FM Approved Components). (See Fig. 8.). 24 Table 10. Minimum Metal Disk or Fastener Head Size (Base Sheet Fasteners) Table 11. Allowable 2 Uniform Uplift Pressure Table 12. Nail pullout strength per in. (25 mm) of penetration... 31

3 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page SCOPE This data sheet provides recommendations for the proper securement of various roof decks to supporting members, and for the proper design and installation of above-deck roof components. Items covered include roof covers, insulation, vapor retarders, fasteners, and recover assemblies. This data sheet is intended to be used in conjunction with Data Sheet 1-28, Wind Design. Prefabricated panel roofs, lap seam, and standing seam roofs are covered in Data Sheet 1-31, Metal Roof Systems. Other data sheets with information on roofing include: Data Sheet 1-28, Wind Design Data Sheet 1-30, Repair of Wind Damaged Roof Systems Data Sheet 1-32, Existing PVC Roof Covers Data Sheet 1-33, Safeguarding Torch-Applied Roof Installations Data Sheet 1-49, Perimeter Flashing Data Sheet 1-52, Field Uplift Tests Data Sheet 1-54, Roof Loads For New Construction (which covers positive [snow, ponding] loads) For roofs of buildings divided by maximum foreseeable loss (MFL) fire walls, refer to Data Sheet 1-22, Criteria for Maximum Foreseeable Loss Fire Walls and Space Separation. 1.1 Changes September Minor editorial changes were made for this revision. 2.0 LOSS PREVENTION RECOMMENDATIONS 2.1 Introduction The recommendations provided in this document are not intended to supersede the requirements of any FM Approval (see Appendix A for definition). FM Approval listings outline the field-of-roof securement requirements. Some listings also may contain specific roof corner/perimeter fastening methods. This data sheet outlines other roof perimeter/corner fastening methods. Use the recommendations to supplement the listings in the Approval Guide, a publication of FM Approvals. Where appropriate, recommendations are grouped in each section as Design, Installation, and Maintenance. Roof systems are FM Approved only for certain wind uplift ratings. All recommendations are for systems used within their FM Approval limits. Generally, recommendations regarding internal fire ratings (Class 1 or 2) are not applicable to structural concrete and gypsum roof decks, as these decks are rated noncombustible (internally) regardless of the above-deck components due to the substantial thermal barrier offered by the deck itself. Form boards used with gypsum decks may themselves be combustible. 2.2 Construction and Location General These recommendations are applicable to all systems except as noted Design Recommendations Except for ballasted systems that are not FM Approved, ensure all installations use components and systems (roof deck, insulation, fasteners, roof cover, etc.) that are FM Approved for use together on the particular deck. Use of individually FM Approved components, not FM Approved for use together, does not

4 Page 4 FM Global Property Loss Prevention Data Sheets constitute an FM Approved or recommended assembly. Use of FM Approved systems is universally recommended and is implied for all applicable assemblies whether or not specifically stated in the recommendation All FM Approved materials are required to have the FM Approval mark on the packaging or the material itself. Materials without proper labeling are not FM Approved and cannot be accepted Ensure the roof deck design and installation are in accordance with the Approval Guide, RoofNav and Data Sheets 1-28, Wind Design, 1-49, Perimeter Flashing (and 1-31, Metal Roof Systems, where applicable) Use FM Approved perimeter flashing systems, where available. Secure wood nailers in accordance with Data Sheet 1-49, Perimeter Flashing, and follow other guidelines in that document where FM Approved flashings are not available Ensure roof slope is a minimum of 1 ( 1 4 in./ft, 21 mm/m). This can be accomplished by varying the column heights or using an FM Approved tapered insulation system. Refer to Data Sheet 1-54, Roof Loads for New Construction Installation Recommendations It is essential that thorough supervision by the building owner s qualified representative is provided during all roof construction to ensure quality of workmanship and adherence to FM Approval standards and project specifications When installing torch-applied roof covers, follow the recommendations in Data Sheet 1-33, Safeguarding Torch-Applied Roof Installation, and recommendation Do not store combustible roofing materials in buildings under construction unless an adequate sprinkler system is in service. Use combustible adhesives and solvents with caution. Use FM Approved safety cans where appropriate. Do not allow smoking on roofs at any time. Do not allow flammable liquids or solvents to enter confined spaces. Ensure the facility s emergency response team oversees all roofing work Make a minimum of two 10 lb (4.5 kg) ABC fire extinguishers available on the roof during roof construction and repairs Due to possible high concentrated loads from the rolls of membrane and gravel carts, caution is needed when moving these materials across the roof. To prevent over-stressing the deck when the weight of individual rolls of single-ply membrane exceeds 1100 lb (500 kg), use precautions such as shorter deck spans or plywood sheets over steel deck to reduce point loads Fill the space between nailers in roof expansion joints with noncombustible, compressible insulation such as glass, mineral, or ceramic fiber type Provide adequate separation and/or noncombustible insulation between hot exhaust stacks and combustible roof deck and above deck roof components. See DS 1-13, Chimneys, for details Ensure roof insulation or cover boards are dry and surfaces are free of debris or dirt prior to adhering roof covers to them. This will help ensure complete adhesion of the cover to its substrate Maintenance Recommendation Inspect roof systems and flashing semi-annually and after storms. During inspection, note and repair any holes or deterioration of the covering, opened seams, backed-out fasteners, loose anchorages, loose flashing, membrane shrinkage, etc. Replace any wet insulation when making roof repairs. Inspect and clean drains as needed. Maintain written records Wind Uplift Resistance: Design Recommendations Determine the roof wind uplift design pressure and recommended FM Approvals wind uplift ratings for roof assemblies (decks and above-deck components) per Data Sheet 1-28, Wind Design or RoofNav Ratings Calculator. Do not use any system beyond its FM Approval rating, except where enhancements are allowed by this document.

5 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page Ensure all new, re-roof, and recover construction uses an appropriate wind-uplift-rated FM Approved roof system where available. Ensure the roof field fastening is per FM Approvals RoofNav listing. Note: For ballasted systems, see sections to Because there are higher uplift forces on the roof corners and perimeter, these areas need additional securement over that, which is FM Approved for the field of the roof. Refer to Data Sheet 1-28 for corner/perimeter definitions and dimensions. Ensure any whole or partial insulation board or roof cover/base sheet width (when the roll is parallel to the building edge) that falls within the calculated perimeter or corner has the increased securement applied over the entire board or roof cover/base sheet width. There are several acceptable methods for increasing the uplift resistance of the roof in the corners and perimeters. Do one of the following: Where the FM Approvals RoofNav listing includes a roof perimeter and/or corner fastening method, it can be used. Use a roof system with the appropriate FM Approval wind uplift rating in each area per Table 1. Use the appropriate prescriptive recommendation noted in section , within the limits of acceptability. An alternative is to use an adhered roof cover (adhered across the entire roof) that is adequately wind rated for the field of the roof and, in the perimeter and corner areas, use a mechanically attached roof cover (see Table 1 and ) that is either: a) FM Approved for wind pressures in the perimeter and corner areas, or b) FM Approved for the field of roof pressure per Table 1 and enhanced in the perimeter and corner areas per recommendation by reducing the distance between rows of fasteners. In either case a) or b) above, fasten a termination bar over the cover or base sheet (with suitable weatherproofing provided) and into the deck every 6 in. (150 mm) on center. Use minimum no. 15 screws at the junction of the fully adhered areas with the adhered and mechanically fastened areas. Table 1. Recommended Rating of Field, Perimeter, and Corner Areas (Zones 1, 2, and 3) for Enclosed Buildings Minimum Wind Rating for FM Approved Deck/Above-Deck/Entire 1 Assembly Roof Field Area Design Pressure, p, (psf) 2 Roof Field Area Enclosed Bldg. Roof Perimeter Area Enclosed Bldg. Roof Corner Area Enclosed Bldg. p <p < p <p < p <p < p <p < p <p < p <p < p <p < p Base the minimum wind rating on the roof field area rating when perimeter/corner areas are enhanced per this data sheet and other pertinent FM Global Data Sheets (1-29, 1-31, etc.). Base the minimum wind rating on the respective area rating when perimeter/corner area enhancements are not done, or are not acceptable. 2 For roofs with higher field area design pressures, or to interpolate needed perimeter and corner ratings when the field requirements are between levels, multiply the needed field area design pressure from Table 3, 4 or 5 (of D.S. 1-28) by a safety factor of 2.0 and the respective pressure coefficient per Table 6 of D.S. 1-28, and round up to the next highest 15 psf rating interval. 3 Ratings above apply to enclosed buildings, with roof slopes 7 and roof heights 60 ft (18 m).

6 Page 6 FM Global Property Loss Prevention Data Sheets Prescriptive Enhancement Options: Perimeter and Corner a) For all deck types, where roof covers are adhered to some combination of mechanically fastened insulation, cover board, or thermal barriers, prescriptive enhancements may be used for securement of the perimeter and corner areas, as long as one of the conditions below applies: 1. The building is in a non-hurricane prone region where the design wind speed does not exceed 90 mph and the roof height does not exceed 75 ft (23 m). Note the roof height is limited to 30 ft (9.1 m) if the building is located in surface roughness exposure D (see DS 1-28) and the building is partially enclosed. Or, 2. The recommended field of roof rating needed per DS 1-28 does not exceed Class 1-75 (3.6 kpa). Or, 3. The building is in a non-hurricane-prone region (see Appendix A) and the recommended field of roof rating per DS 1-28 does not exceed Class 1-90 (4.3 kpa). For any of the three conditions above, increase the number of fasteners per board over the FM Approved field-of-roof spacing by the following: 50% minimum in the roof perimeter, but at least one fastener per 2 ft 2 (1 per 0.19 m 2 ). It is not necessary to install fasteners closer than one per 1 ft 2 (1 per 0.09 m 2 ). One fastener per 1 ft 2 (1 per 0.09 m 2 ) in corner areas. Round up to the next whole number of fasteners, if necessary b) For all locations (including hurricane-prone regions), where a Class 1-90 wind rated system is needed for the field-of-roof, use the following generic assemblies in the perimeter and corner areas to provide acceptable wind resistance in those areas: Option 1 Minimum in. (38 mm) thick, FM Approved, Class 1 insulation laid loose directly on the deck. Minimum 1 2 in. (12. 7 mm) thick, FM Approved, water resistant, primed (factory or field primed) gypsum cover board over the insulation. Primer can be omitted if roof cover / coverboard combination meets a Class or greater without a primer. Through-fasten both layers to the steel deck with FM Approved minimum No. 14 ( 1 4 in., 6.4 mm) screws and flat-bottom metal stress plates. Use 24 fasteners per 4 by 8 ft (1.2 by 2.4 m) board in the perimeter, and 32 fasteners per 4 by 8 ft (1.2 by 2.4 m) board in the corners. Roof cover a fully mopped, minimum 3-ply BUR; or a minimum 2-ply mod bit system with all plies fully mopped and/or torch applied per FM Approval requirements. Option 2 Minimum 2 in. (50 mm) thick, FM Approved, Class 1 insulation laid loose directly on the deck. Note: a lesser insulation thickness may be used if included in any Class 1 fire-rated assembly with the other components above it, but not less than in. (38 mm) thick. Minimum 7 16 in. (11.1 mm) thick, oriented strand board (OSB) cover board over the insulation. Ensure the OSB is APA (American Plywood Association) rated for Exposure 1, with exterior type adhesive. Through-fasten both layers to the steel deck with FM Approved minimum No. 14 ( 1 4 in., 6.4 mm) screws and flat-bottom metal stress plates. Note: if screws have oversized heads and are specifically approved for OSB or OSB composite boards, stress plates are not required. Use 24 fasteners per 4 by 8 ft (1.2 by 2.4 m) board in the perimeter, and 32 fasteners per 4 by 8 ft (1.2 by 2.4 m) board in the corners. Roof cover a minimum 3-ply BUR or minimum 2-ply mod bit system with all plies fully mopped, per FM Approval requirements.

7 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page 7 c) For areas where the criteria in the recommendations above are exceeded, ensure the roof system used in the perimeter and corner areas is FM Approved for the specific wind rating recommended in the perimeter and corner areas (see Table 1). Alternatively, install either a mechanically attached single-ply membrane, or a multi-ply roof cover with a mechanically attached base sheet in accordance with Note: Insulation and thermal barriers under mechanically fastened roof covers in assemblies that DO NOT incorporate air or vapor retarders do not have to increase the insulation fastening over the field of roof spacing For components adhered with urethane-based adhesives, asphalt, or other adhesives in ribbons, spots, etc., reduce the spacing between ribbons or spots over the FM Approved field-of-roof spacing as noted below (round down to a dimension that is practical with respect to board sizes, etc.): In the roof perimeter, not more than 60% of the field-of-roof spacing between rows or area In the roof corners, not more than 40% of the field-of-roof spacing between rows or area Note: If the FM Approval rating for wind meets the criteria in Table 1 for the perimeter or corner area, no further reduction is needed in those areas. Example: A particular roof cover as FM Approved is adhered with a urethane-based adhesive in ribbons at 1 ft (0.3 m) on center in the field of the roof. The perimeter would need a ribbon spacing of 6 in. (150 mm) and the corners would need a ribbon spacing equal to 4 in. (100 mm) on-center. Note: these spacings were rounded down slightly for practicality For mechanically attached single-ply membranes, and multi-ply covers with a mechanically attached base sheet, refer to section For mechanically attached base sheets, refer to section or if the base sheet is fastened directly to a wood deck For ballasted systems, refer to section For steel decks, increase the number of deck fasteners at each joist or purlin support over the field-of-roof FM Approvals RoofNav listing in accordance with Shorter spans that yield an equivalent increase in deck securement strength are acceptable, but may not always be practical External Fire ResistanceDesign Recommendations Assemblies having an American Society for Testing and Materials (ASTM) E108 Class A rating are preferred in all cases, and are specifically recommended as follows: a) Where the exterior fire exposure to the roof is severe. b) On the entire roof of buildings subdivided by MFL fire walls. Refer to Data Sheet 1-22, Criteria for Maximum Foreseeable Loss Fire Walls and Space Separation, for details on additional surface protection needed adjacent to the wall and roof protection for buildings where MFL space separation is a factor. c) For occupancies particularly susceptible to smoke or water damage ASTM E108 Class C rated assemblies are not recommended on any roofs >10,000 ft 2 (930 m 2 ) The use of pea gravel surfacing installed in accordance with is considered to provide a Class A exterior fire exposure rating. While not normally recommended in hurricane-prone regions due to its potential to become windborne debris, it may be accepted in hurricane-prone regions (such as where required adjacent to fire subdivisions), provided that all gravel remaining at the end of the installation is fully embedded into the bitumen and there is no loose gravel nested on top. The following method will provide such compliance: a) Aggregate is applied into a flood coat of hot bitumen, and allowed to cool and harden. b) Loose aggregate is pushed away, a second flood coat is applied, and the loose gravel is applied back into the second flood coat and allowed to cool and harden. c) Any remaining loose gravel is removed from the site.

8 Page 8 FM Global Property Loss Prevention Data Sheets Hail Resistance: Design Recommendations Use only FM Approved roof cover systems meeting the severe hail (SH) criteria in the hail storm hazard area shown in Figure 1. Unless specifically FM Approved with other surface treatments, built-up roofs (BUR) may be used in SH and MH areas, provided: they are covered with gravel at a minimum of 400 lb per square (19.5 kg/m 2 ) or slag at a minimum of 300 lb per square (14.6 kg/m 2 ). (See Appendix A, Glossary, for definition of square.) aggregate is in accordance with ASTM D1863. aggregate is applied into a minimum 60 lb per square (2.9 kg/m 2 ) bitumen flood coat. Note: Do not use pea gravel in regions prone to hurricanes, typhoons ancd tropical cyclones except where installed in accordance with section Otherwise, use FM Approved coatings in lieu of pea gravel For U.S. locations outside the hail area, MH or SH rated systems can be used At locations outside the U.S., MH rated systems can be used unless local weather records indicate the need for greater hail resistance. Generally, consider SH rated systems for locations with an average of three or more hail storms per year Internal Fire ResistanceNoncombustible, Class 1, and Class 2 AssembliesDesign and Installation Recommendations As all FM Approved roof systems are Class 1 or noncombustible, Class 1 or noncombustible assemblies are recommended in all cases. When there is an existing Class 2 deck and an unsprinklered concealed space below the deck, refer to Data Sheet 1-12, Ceilings and Concealed Spaces, for fire protection guidance Class 2 steel roof decks can be converted to Class 1 by applying an FM Approved undercoating. If this is done, adhere to the following recommendations: Ensure the underside of the deck is clean before coatings are applied. Ensure FM Approved coatings are applied by applicators licensed by the coating manufacturer. Do not use cellulose-based undercoatings in high humidity occupancies as the fire retardant chemicals are water soluble and can leach out of the coating. Do not use steel deck undercoatings where combustible residue can accumulate on the surface Vapor Retarders (Barriers)Design and Installation Recommendations These recommendations outline vapor retarder applications that maintain Class 1 and appropriate wind uplift ratings If a vapor retarder is used, ensure it is FM Approved and applied in a single layer placed directly on the deck. Side and end laps are sealed using FM Approved adhesive. The remaining roof components are then installed with fasteners driven through the retarder into the deck (Fig. 2). The components above the FM Approved vapor retarder can be any combination of materials FM Approved for use together on the particular deck. Some systems are FM Approved with the retarder installed above a base layer of insulation; see section below On panel-type decks (decks with seams such as steel, wood, pre-cast planks, etc.), if a vapor retarder is installed below the insulation or coverboard of a mechanically secured single-ply membrane (per recommendation above), secure the insulation or coverboard with FM Approved insulation fasteners and plates using one of the following options: 1. A rate of 1 per 2 ft 2 (1 per 0.19 m 2 ) throughout the entire roof area, OR 2. A rate throughout the entire roof area that will obtain a minimum 1-90 uplift FM Approval with an adhered single-ply roofing membrane as specified in a RoofNav listing. The insulation/coverboard type used below the mechanically secured membrane must match that specified by the RoofNav listing for the adhered membrane, and the thickness of the insulation/coverboard must be equal to or greater than that specified by the RoofNav listing. A vapor retarder is located on the warm side of the roof or sandwiched between insulation layers. The vapor retarder is sealed to the exterior walls of the building, but not necessarily to the underside of the roof cover.

9 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page 9 Gander Churchill St. Johns Hudson Bay Buchans Gulf of St. Lawrence Ja mes Bay Sidney Charlottetown Chatham Halifax Quebec Sioux Lookout Bangor Montreal Winnipeg Seattle Port Arthur Spokane Montpelier Ottawa Portland In ternational Falls Concord Saranac Lake Boston Duluth Toronto Helena Fargo Bismarck Albany Baker City Providence Hartford Aberdeen Buffalo Boise Philadelphia Ludington Sheridan Pierre Minneapolis Pittsburgh Detroit Trenton Milwaukee Pocatello Harrisburg Sioux Falls Eureka Baltimore Cleveland Red Bluff Lander Chicago Washington DC Fort Wayne Moline Reno Columbus Cincinnati North Platte Sacramento Salt Lake City Indian apolis Kahoka San Francisco Norfolk Charleston Springfield Kansas City Topeka Saint Louis Louisville Wytheville Fresno Knoxville Wichita Ashville Springfield Las Vegas Nashville Joplin Memphis Santa Fe Chattanooga Charleston Amarillo Atlanta Phoenix Birmingham San Diego Savannah Montgomery Tucson Dallas Mobile El Paso Jacksonville New Orleans Tampa San Antonio Houston Gulf of Mexico Miami NEWFOUNDLAND Prince Rupert CANADA Prince George Edmonton The Pas Prince Albert Amherst Saskatoon Kamloops C algary Vancouver Penticton Kapuskasing Regina Nelson Cranbrook Medicine Hat Gulf of Maine Havre Sault St Marie Huntsville Lake Superior Marquette London Green Bay Souix City Des Moines Cheyenne Richmond Denver Williston Lake Huron Billings Lake Michigan Atlantic Ocean Raleigh Pueblo Fort Smith Little Rock Shreveport Jackson Columbia Los Angeles Oklahoma City Gulf of California MEXICO Fig. 1. Hailstorm hazard map for United States (areas subject to severe hailstorms and need an SH hail rated roof) H ecate Strait Clayoquot Victoria Pacific Ocean Exposure to Damaging Hailstorms Moderate Severe No Data Kilometers Miles 2009 Factory Mutual Insurance Company. All rights reserved

10 Page 10 FM Global Property Loss Prevention Data Sheets Fig. 2. Insulation and vapor barrier mechanically fastened to steel deck. An air barrier is used with a mechanically fastened roof cover and is located directly above the roof deck. The air barrier is sealed to the underside of the roof cover, but not necessarily to the exterior walls of the building. In theory, an air barrier improves wind uplift resistance of the roof assembly by preventing air flow into the space below the roof cover and transferring a portion of the uplift load to the insulation. It should be noted that even for properly installed air barrier systems, roof penetrations made after the installation of an air barrier system can hamper the wind performance of an air barrier system if the air barrier is not sealed to the underside of the roof cover after the penetration cut is made. Consequently, there are special FM Approval restrictions on air barrier systems Fastener penetration of the vapor retarder can be avoided by using an FM Approved fastened/adhered assembly. Ensure all materials are FM Approved for use in combination. Ensure substitution of materials is not made Do not mop asphalt/felt vapor retarders directly on to any deck (this would result in a Class 2 roof) except structural concrete Roof Insulation Design Recommendations Ensure insulation boards are FM Approved for the specific application, including specific roof cover, fasten/mop construction, multiple layers, etc. Using assemblies that are not FM Approved can result in a Class 2 and/or inferior roof construction. However, combinations that may not be FM Approved but can be accepted are noted in sections , , and It is acceptable to use multiple layers of FM Approved insulation, mechanically secured through all layers, provided all of the following are true: All layers are the same insulation. The total insulation thickness is not greater than the maximum FM Approved thickness of the insulation. The mechanical fastening and wind uplift rating are per the FM Approval of the top layer. The roof cover/insulation/fastener combination is FM Approved Insulation board sizes listed in the Approval Guide are the minimum FM Approved sizes. Boards up to 4 8 ft ( m) can be used except as noted in section (with a proportional increase in fasteners, adhesive ribbons, etc. rounding up to the next whole number). Do not use boards smaller than FM Approved except per section

11 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page The maximum recommended insulation board size, if the board is adhered with asphalt or adhesive, is 4 4 ft ( m). Exception: Flexible boards such as maximum 1 2 in. (13 mm) thick wood fiber or 5 8 in. (16 mm) gypsum board may be adhered at board sizes up to 4 8 ft ( m) Installation Recommendations Stagger insulation board joints in one direction (the shorter sides staggered if boards are not square). Support the two opposite sides of each board on steel deck flanges, as close as practical to the center of the flange with a minimum bearing width of 1 in. (25 mm). Trim board edges if they veer off the flange center When insulation boards are cut, as is common at the roof edge to produce staggered joints, secure each piece with the appropriate number of fasteners, adhesive ribbons, etc. for the full board times the percentage area of the piece, rounding up to the next whole number Install only as much insulation or gypsum-based board as can be covered each working day. Seal loose roof cover edges at the end of each day to minimize moisture damage. Do not allow water to run in steel deck ribs under completed roof sections Ensure insulation is set on pallets or dunnage and protected from the weather and sunlight prior to installation. Do not allow plastic to cover the insulation as it can allow condensation. A breathable material, such as canvas, is recommended Ensure FM Approved job-mixed material (like LWIC) is installed by applicators licensed by the manufacturer. Steel deck that meets the insulation manufacturer s span and gauge requirements is necessary to support the application equipment. Such systems are a possible option when penetration of the deck with mechanical fasteners is not desired Provide preliminary securement of insulation boards when mechanically fastened roof covers are used (single-plies or multi-plies with fastened base sheets). Install a minimum of two fasteners per4x4ft(1.2 x 1.2 m) board or four fasteners per 4x8ft(1.2 x 2.4 m) board, unless the manufacturer requires a greater number. Additional insulation fastening is not required in the perimeter and corner areas. Where a vapor retarder is used below a mechanically fastened roof cover, see section Insulation and Roof Cover Fasteners Design Recommendations FM Approved insulation fasteners are the only FM Approved and recommended method of securing insulation boards or other boardstock materials to steel deck. Some fasteners are FM Approved for other deck materials When fastener pull-out tests are performed on new construction to evaluate the deck integrity or evaluate decks that are not FM Approved, run a minimum of five tests and use the average value. See section for the number of tests for recover/reroof construction When pull-out tests are done, base the fastener density on the more conservative of either the FM Approved spacing for the fastener plate/insulation/roof cover combination, or the spacing needed based on the average pull-out performance. Example: An existing deck is oriented strand board (OSB). The fastener/insulation/roof cover combination is FM Approved for 4 fasteners per 4 4 ft ( m) board for Class 1-90 on steel deck. The calculated load per fastener would be 360 lb (1600 N) ([4 ft 2 /fastener][90 psf] = 360 lb/fastener). If the proposed fastener achieved a pull-out resistance of 360 lb (1600 N) or more in the deck, the FM Approved spacing would be used. If the fastener achieved a resistance of less than 360 lb (1600 N), for example 300 lb (1335 N), calculate the spacing as follows: (16 ft 2 )(90 psf)/(300 lb) = 4.8 fasteners per board; use five fasteners per board in the roof field. Additional fasteners would be needed in the corners and perimeter per section The percentage increase would be applied to five fasteners per board, not four Installation Recommendations Install fasteners only through dry substrates. Wet constructions can cause deterioration of fasteners, including FM Approved corrosion-resistant fasteners. Exception: Fasteners FM Approved for use in new lightweight insulating concrete decks are designed to be tolerant of the moisture present at the time of installation.

12 Page 12 FM Global Property Loss Prevention Data Sheets Use only FM Approved fastener/plate combinations. Do not install stress distribution plates from one manufacturer with another manufacturer s fastener unless the combination is FM Approved Fasteners must be driven perpendicular to the deck to be effective. Particular caution is needed with tapered insulations Use the manufacturer s proprietary installation tool. A less desirable option is a properly adjusted screw gun, having a depth-sensing clutch, to avoid over-driving or under-driving screw-type fasteners Recommended Fastener Embedment: Sructural concrete: 1to1 1 2 in. (25-38 mm), Wood decks: Minimum 1 in. (25 mm). Note: For 3 4 in. (19 mm) thick plywood deck, approximately 1 4 in. (6 mm) of the screw will protrude through the deck underside. Steel deck: For screw-type fasteners in new construction, use the shortest screw that is at least 3 4 in. (19 mm) longer than the assembly being secured. Ensure fasteners engage the deck top flange. For recover steel deck construction, the fastener must be long enough to be driven through the existing roof system and into the deck at least 3 4 in. (19 mm). While top flange engagement is recommended in all cases, for recover construction, it is acceptable for insulation fasteners to engage the bottom flange of the deck. Ensure fasteners securing mechanically attached roof covers engage the top flange of the deck in all constructions. For other deck types: Follow the FM Approval requirements and manufacturers specifications Ensure insulation fastener placement is per Figures 3, 4, 5, and 6. If a particular insulation has a different required FM Approved fastener pattern, use that. Each fastener must engage the intended deck flange. This results in a spacing tolerance of approximately ± 1.5 in. (± 38 mm) for wide-rib deck if the edge of the board was at the centerline of the deck top flange. For smooth decks, such as plywood or concrete and steel deck in the direction of deck ribs, a maximum tolerance of ± 1.5 in. (± 38 mm) is acceptable.

13 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page 13 Fig. 3. Fastener placement 2 4 ft( m) boards.

14 Page 14 FM Global Property Loss Prevention Data Sheets Fig. 4. Fastener placement 3 4 ft ( m) boards.

15 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page 15 Fig. 5. Fastener placement 4 4 ft ( m) boards.

16 Page 16 FM Global Property Loss Prevention Data Sheets Fig. 6. Fastener placement 4 8 ft ( m) boards. For fastening densities not shown, the following guidelines apply: Ensure edge fasteners are 6 in. (152 mm) from the board edges, with tolerance as above. Ensure fasteners are evenly distributed over the board area. Ensure all fasteners engage the top flange of steel deck. (See note for recover construction, section above.) Recover and Reroof ConstructionDesign and Installation Recommendations This section covers planned recover and reroof operations. For repairs after wind damage has occurred, refer to Data Sheet 1-30, Repair of Wind Damaged Roof Systems Reroof ConstructionRemoval and Replacement of Above-Deck Components Reroof construction is generally preferred to recover construction due to the potential for moisture damage with recover construction from existing wet insulation inadvertently left in place.

17 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page When reroofing, inspect the existing deck securement and, if necessary, fasten the deck per Data Sheet 1-28, Wind Design, prior to installation of the above-deck components When reroofing over a steel deck where the original assembly had been adhered with asphalt, do one of the following: Use an insulation specifically FM Approved for reroofing; that allows up to 15 lb per square (72 kg/100 m 2 ) of asphalt to remain on the deck. Remove all asphalt from the deck and install a system FM Approved for new construction Recover ConstructionExisting Components Remain All recover recommendations and FM Approvals are based on the assumption that there is only one existing roof system. If more than one roof system is in place (building has already been recovered), use reroof construction If recover construction is considered, perform the following actions: Remove all wet materials prior to application of the new roof system, with wet insulation being replaced with dry material. Cut out blisters. Roof cover blistering or rusting deck may be an indication that the existing insulation is wet. When this is observed, take one of the following steps: Reroof, as opposed to recover. See section Conduct an infrared or nuclear examination to detect any high-moisture content. If moisture is detected with one of these nondestructive methods, confirm the results by cutting out 1 1ft ( m) samples or roof cores as needed to determine the extent of wet insulation Recovermechanically attached recover systems. If the existing construction is dry, an FM Approved recover system can be applied over it. Ensure the entire assembly (insulation, fasteners, and roof cover) is FM Approved in combination for recover construction on the particular deck Ensure the thickness of the recover system is within the FM Approval limits. Most systems are limited to a maximum 1 in. (25 mm) thick roof insulation. A greater thickness may affect the Class 1 fire rating of the completed system. Installation of an FM Approved Class 1 recover assembly over an existing Class 2 roof system will not upgrade the assembly to Class 1. However, it would be possible to upgrade the external fire resistance rating (E108) with the addition of an FM Approved roof cover system When brooming gravel from the roof, do not pile it in one area. This can overload structural members causing collapse Do not use recover constructions using additional plies adhered directly to an existing BUR unless the entire assembly is FM Approved. This would essentially result in a 6- or 7-ply BUR over the insulation (3- or 4-ply existing BUR plus 3 plies added), most likely creating a Class 2 roof assembly When reroofing or recovering over gypsum, cementitious wood fiber, or lightweight insulating concrete decks, verify fastener pull-out performance with field tests. Perform 5 pull-out tests per 50,000 ft 2 (4650 m 2 ) using FM Approved fastening or a minimum of 5 tests. Run additional tests if inconsistent results are obtained. On larger roofs, the number of tests above the minimum can be reduced if consistent results are obtained. Fastener spacing is calculated per section It is not necessary to run pull-out tests of fasteners FM Approved for installation in steel deck, structural concrete, nominal 3 4 in. (19 mm) plywood, or nominal 2 in. (51 mm) lumber decks, unless the condition of the deck is in question Structural Concrete, FM Approved Fiber Reinforced Cement and Lightweight Insulating Concrete (LWIC) Decks: Design and Installation Recommendations NOTE: also see section for LWIC and for Structural Concrete Decks When an FM Approved asphaltic adhesive or asphalt is used to secure components to these decks, prime the deck with an FM Approved primer at the FM Approved rate, or with an ASTM D-41 asphalt cut-back primer at 0.75 to 1.25 gal per square (3.0 to 5.1 L/10 m 2 ).

18 Page 18 FM Global Property Loss Prevention Data Sheets Single-Ply Membrane Covers and Multi-Ply covers with Mechanically Attached Base Sheets Loss experience has shown that even properly secured single-ply roof covers can be damaged by windborne debris such as metal panels and broken glass. In areas prone to hurricanes, typhoons and tropical cyclones (see DS 1-28), use more durable roof covers. This would include multi-ply roof covers or single-ply membranes that are considerably thicker than the FM Approved minimum. Many single-ply membranes are manufactured in thicknesses up to to in. vs. the minimum FM Approved thickness of to in General Single-ply membranes can deteriorate when exposed to certain materials commonly discharged onto the roof. Also separate these membranes from incompatible substrate materials. In particular, ensure single-ply membranes do not come into contact with asphalt or coal tar-based materials. Ensure EPDM membranes are not exposed to gasoline, oil, solvents, or animal fats. Ensure PVC membranes are not in direct contact with EPS. Follow the manufacturer s recommendations for protection or separation Some FM Approved single-ply membranes are formulated with fire retardants on the top side only. Install these systems with that surface up. Membranes with this requirement are labeled on the underside THIS SIDE DOWN/IN Mechanically Attached Single-ply Membranes and Multi-Ply Covers with Mechanically Attached Base Sheets: Design Recommendations In the roof corners and perimeter, ensure the distance between rows of roof cover fasteners or batten bars are the following maximum percentages of the FM Approved spacing. Use the reduced spacing in all FM Approval classifications: Roof Perimeter: Distance between rows is 60% of the FM Approved roof field spacing, or one row of intermediate fasteners is provided in between. Roof Corners: Distance between rows is 40% of the FM Approved roof field spacing or two rows of intermediate fasteners are provided in between. An alternative for Class 1-90 and below (on steel deck) is to install perimeter fastener rows (60% of roof field as above) in both directions in the corners (any wind class acceptable for other types of decks). Refer to Figure 7. When the cover overlaps in the corner areas, install these fasteners from above the uppermost cover layer. For single-plies fastened along the side laps: Increased fastening density for single-ply membranes is often obtained by using narrower sheets. For single-ply membranes or base sheets, intermediate rows of fasteners may be installed through the sheet with a cover strip or additional plies applied over the fasteners, in accordance with the manufacturer s instructions. Use one intermediate row in the perimeter and two intermediate rows in the corners. Fastening increase is not always obtained by increasing the number of fasteners along each row, unless substantiated by FM Approval test data or otherwise done to provide a more practical spacing and distribution of wind loads. In some cases, such as over wood decks (see ) or LWIC, or with mod bit base sheets in high wind areas, enhanced securement for base sheets is provided by reducing the fastener spacing within and between rows in order to provide a uniform distribution (see section for examples). When steel deck is used, the fastener spacing across the deck ribs must be in even multiples of the deck rib spacing (6 in. or 150 mm for in. or 38 mm deep deck) to ensure the fastener engages the top deck flange. See Example 1. For point-attached membranes: Increased fastening density is obtained by decreasing the spacing between fastener points in one or both directions. Ensure total tributary area to each fastener is no more than 60% and 40% in the perimeter and corners, respectively, of the FM Approved roof field spacing. See Example 2. Example 1: A batten-attached system with FM Approved fastener spacing for Class 1-60 of rows 6 ft (1.8 m) on center and screws 6 in. (152 mm) on center would use 3.6 ft (1.1 m) maximum on center row spacing, with 6 in. (152 mm) on-center screw spacing in the perimeter and 2.4 ft (0.7 m) maximum on-center row spacing with 6 in. (152 mm) on-center screw spacing in the corners. In this case, rows of roof cover fasteners should extend across the deck ribs in all areas to properly distribute the load to points of deck securement. Since the needed wind uplift rating is limited, an option would be to use row spacing of 3 ft (0.9 m) maximum in both directions in the corners per Figure 7, and

19 Roof Deck Securement and Above-Deck Roof Components 1-29 FM Global Property Loss Prevention Data Sheets Page 19 Notes: 1. Fastener spacing along all rows is the same as field spacing. 2. See section for restrictions on fastener rows parallel to steel deck ribs. 3. If two layers of membrane are installed in the corner areas, all fasteners must secure the top layer. Fig. 7. Alternate corner increase for mechanically attached single-ply membranes. Note: Fastener spacing along all rows is the same as field spacing.

20 Page 20 FM Global Property Loss Prevention Data Sheets Example 2: A point-attached system with FM Approved fastener spacing for Class 1-90 of in. ( mm) could use a spacing of in. ( mm) in the perimeter. A in. ( mm) spacing may be needed for steel deck applications depending on deck rib direction. A spacing of in. ( mm) in the corners could be used. A in. ( mm) may be needed for steel deck applications depending on deck rib direction Mechanically Attached Single-Ply Membranes and Multi-Ply Covers with Mechanically Attached Base PliesInstallation Recommendations Ensure all roof cover fasteners engage the top flanges of steel deck Install batten bars and fastener rows perpendicular to steel deck ribs. Exception: for Class 1-75 and below, fastener rows and batten bars can be installed parallel to the building edge within the defined building perimeter width if: a) the distance between fastener rows in this area is 3 ft (0.9 m), and b) two FM Approved deck fasteners or minimum 5 8 in. (16 mm) diameter welds are installed through each lower deck flange (every 6 in., 150 mm on center) Where acceptable to the roof cover manufacturer, in lieu of seaming numerous partial single-ply membrane sheets in the rake areas, an FM Approved batten bar may extend across the perimeter width, midway between rows of fasteners and be fastened to the deck. Adhere a membrane strip of a minimum width as recommended by the manufacturer over the batten bar and the edges caulked to maintain water-tightness, if needed. Similar enhancements may be provided in the corner areas using two intermediate batten bars Provide deck securement as follows when the FM Approved (field-of-roof) spacing between rows of roof cover fasteners exceeds 6 ft (1.8 m): a) Use only FM Approved deck fasteners to secure the deck. Ensure the spacing within rows of deck fasteners in the field-of-roof does not exceed the spacing within rows of roof cover fasteners. b) Double the deck fastening in the roof perimeter. For example, if roof cover fasteners are 12 in. (300 mm) on center in the field, provide deck fasteners 12 in. on center in the field (per a.) and provide deck fasteners at 6 in. (150 mm) centers in the perimeter. If cover fasteners are 6 in. (150 mm) on center in the field, provide deck fasteners at 6 in. centers in the field (per a.) and provide two deck fasteners at 6 in. (150 mm) centers in the perimeter. c) In corner areas, use the same number of deck fasteners as for the perimeter, but with ¾ in. diameter washers. Ensure washers are carbon steel with a in. (8.4 mm) center hole and are minimum in. (1.6 mm) thick Ballasted Single-Ply Membrane: Design Recommendations Do not use stone-ballasted roofs on buildings taller than 150 ft (46 m) high, or in areas with design wind speeds 100 mph (45 m/s) (See Data Sheet 1-28, Wind Design) or beyond the acceptable limits of Tables 2 or 3. These limitations do not apply to paver ballasted systems To ensure the quality of the materials, component compatibility, and Class 1 undeside fire exposure ratings, ensure individual components in ballasted systems are FM Approved for use in combination. Typically, the combination would be FM Approved for adhered or mechanically attached applications. Use only FM Approved membranes in ballasted applications Ensure stone ballast in loose-laid systems is clean, smooth, well-rounded gravel meeting the gradation requirements of Standard Size No. 3 for Coarse Aggregate per ASTM D448 (nominal 1 to 2 in. [25 to 50 mm] diameter) Ensure the density of stone ballast is approximately 165 pcf (2650 kg/m 3 ). Do not use lightweight stone such as limestone Apply stone ballast per Table 2 or 3. Install paver blocks per Tables 4 to 7. Ensure square edge pavers are a minimum of 1 ft 2 (0.1 m 2 ). Ensure beveled/strapped pavers are a minimum of 0.89 ft 2 (0.08 m 2 ) (8 16 in., [ mm]). All weights are the minimum recommended weights.