By John B. Hickman W. P. Hickman Company Asheville, North Carolina Abstract Originally developed as a design guideline for use by SPRI members, ANSI Standard ES-1-98 has built upon and expanded the intent of that guideline and is now a National Standard. This paper shows how the Standard may be used to improve roof design by assuring a viable edge. The paper also discusses the reasons for developing the stan¬ dard in the first place. Worked examples show the ease with which the Standard can be used. Useful worksheets, keyed to the Standard, are also provided. Included are wind calculations, material limitations, corrosion considerations, and photographs to illustrate the points. John B, Hickman John B. Hickman is the Chairman and CEO of the W. P. Hickman Company, headquartered in Asheville, North Carolina. Mr. Hickman holds a Master’s Degree in Engineering from the University of Michigan. He is chairman of the Single Ply Roofing Institute’s (SPRI) Edge Detail Subcommittee, and is SPRI’s delegate to the Edge Detail Committee of the Roofing Industry Committee on Wind Issues (RICOWI). Mr. Hickman is a member of the Board of Directors of RICOWI, the North Carolina Quality Leadership Foundation (NCQLF), and of the North Carolina Alliance for Competitive Technologies. He has served NCQLF as a Senior Quality Examiner. Hickman is a member of CSI, RCI and NRCA and is a former Director of SPRI.
by John B. Hickman March 15, 1999 The ANSI/SPRI ES-1-98 Standard After six years of work, SPRI, the association of sheet roofing and component manufacturers achieved approval of the industry’s first comprehensive standard for roof edge design. ANSI/SPRI ES-1-98, Wind Design Standard for Edge systems Used with Low Slope Roofing Systems was approved in November 1998 by ANSI, the American National Standards Association. SPRI’s Roof Edge Detail Committee developed the new standard. That group included of representatives of RCI, The National Roofing Contractors Association (NRCA), roofing manufacturers, and the insurance industry. ANSI/SPRI ES-1-98 is the first industry sponsored roof edge design standard. It’s wind force provisions are based on ASCE 7-95, the National Wind Design Standard. Minimum metal thicknesses and corrosion considerations are also part of the new Standard. A “Commentary” section explains the engineering behind its mandatory provisions. The purpose of this paper is to explore this Standard and show how it may be used for better roof design. Reasons For Developing the Standard In The First Place Figure 1: Roof collapse after Hurricane Andrew [courtesy R. Edwards] Hugo/RICOWI Nearly ten years ago, Hurricane Hugo slammed into Puerto Rico and Charleston, South Carolina. Winds exceeded 150 mph with torrential rain. According to Factory Mutual, Hugo “caused $194 million (1990 dollars) in damage to 11,075 insured properties?” Shortly after Hugo, a group, representing various roof-related associations, formed RICOWI, the Roofing Industry Committee On Wind Issues with Charles Goldsmith, AIA, as its chairman. RICOWI’s purpose was to foster research and communication aimed at mitigating the effects of hurricanes and strong winds on roof-related building damage. Immediately, RICOWI established nineteen priorities for study. “Roof Edge Detailing” was the number two priority on that list. Subsequent hurricanes and storms have increased awareness of the need for better roof edge design. Investigators have found that relatively simple steps in edge system securement can potentially head off millions of dollars worth of windstorm damage. The Institute for Business and Home Safety (IBHS) an insurance association, has listed “adequate attachment of commercial edge metal” among its top four most wanted improvements for disaster-resilient structures11 . Each year, about 80% of construction litigation involves water damage and most of that is a direct result of wind and water leaks at the roof edge. a Riding Out the Storm, FM P9106, Factory Mutual Corporation, Norwood, MA. 1997. b IBES, 1998. Figure 3: Roof Destroyed at Edge Structural Formulae Most critical parts of a building are designed using precise structural formulae and codes. In a blow, these parts generally survive. Edges don’t. Yet they are the first defense the roof has against the wind. Once the edge goes, so does the rest of the roof. It doesn’t take a hurricane to rip up a roof edge. Last November, Des Moines was hit by a windstorm that damaged the roofs of a number of schools. The local paper said: “Some schools scrambled to send students home because of ripped up roofs. Van Roekel [a school principal] said that the edging along the roofline blew off, allowing wind under a rubber membrane.c” Figure 2: Poorly secured coping destroyed by wind [courtesy Factory Mutual] apparent to the roofing industry. Inadequate Standards Prior to the development of ANSI/SPRI ES-1-98, rules of thumb, local practices and the suggestions of a few roof edge manufacturers guided edge design advice. The Factory Mutual Research Corporation (FMRC) Property Loss Prevention Data Sheet 1 -49d has been accepted by some as a standard, but its advice is largely prescriptive and is not based on the latest wind design standards. Some have avoided FM 1-49 because it was never intended to be a national standard outside the FMRC organization, and it requires that testing be done only at FMRC’s laboratories. The need for a national design standard for roof edge details has become acutely Specifiers Seek Guidance Many specifiers see the need for better roof edge design. Without a Code or National Standard to back them up, it is difficult for them to defend a specification when a contractor urges the use of a cheapened detail because “it is just as good as” the one detailed by the designer. It is even difficult to defend specification of the edge of a reputable manufacturer. With no standard, it is difficult to compare the merits of different designs. ES-1-98 is that standard. How The Standard Can Be Used To Improve Roof ANSI/SPRI ES-1-98 is a comprehensive work providing rules for wind design, choice of materials, and other design parameters such as nailer coverage. Its wind pressure provisions, while based on the latest wind engineering are easy to follow and quickly calculated. Edges designed to comply with the standard will have adequate metal thickness, good coverage of nailers and appropriate corrosion resistance and will protect the roof from expected windstorms. The standard considers such factors as building location, building use, building environment, comer regions, substrates, and nailer coverage. It also helps a designer to decide which metal pairs to use and what thicknesses to specify. c The Des Moines Register, p4A, Des Moines, IA, November 11, 1998. d Property Loss Prevention Data Sheet 1-49, Roof Edge…, Factory Mutual Corporation, Norwood, MA. 1998. Hickman-2 Appliances Frequently, an edge detail that would have served well is compromised by the use of appliances such as signs or lightning rods that are subsequently attached to the edge. ES-1-98 requires that these be eliminated or isolated to avoid corrosive and other problems. Testing The heart of the document is its test protocols. There are three tests that may be required, depending upon the edge design. There are two blow-off tests, one for coping and one for fascia. There is also a membrane pullout test for those fascia systems that are intended to terminate ballasted or mechanically attached roofing membrane systems. Membrane Pull-Out (Test RE-1) The protocol for this test requires that the membrane be pulled at a 45° angle. A 100-pound resistance passes this test. See Figure 3. Figure 3 Membrane Tensile Test Base General Test Layout for Membrane Pullout Test Membrane Termination Detail —7 Blow-Off Tests (Tests RE-2 and RE-3) The Standard requires static tests of full-length sections of roof edge. Full-length assures that all of the components will be stressed as they would be in the field. Test RE-1 for fascias is rather straightforward. Test RE-3 for copings is complicated somewhat by the requirement that a coping be tested simultaneously in horizontal and vertical directions and that the test be run twice, once against the top and face and once against the top and back leg. The forces on the coping must be applied in the exact ratio of design pressures calculated for the top and the faces. We shall work examples of these calculations. Figure 4 shows one embodiment of the testing apparatus for RE-2 and RE-3. It is a hydraulically operated device built by W.P. Hickman Company. Other roof edge manufacturers and at least one national testing laboratory have similar devices at this writing. Worked Examples Worked examples show the ease with which the Standard can be used. Worked calculation sheets appear at the end of this paper. There is also a blank sheet, which may be reproduced as required. Figure 4: Device for performing tests RE-2 and RE-3 [W.P. Hickman Company photo] Hickman-3 Example 1, Florida High-Rise (Worksheet Appendix 1) Consider a 100-foot high hospital in downtown Lakeland, Florida. The unit is to have a 16-inch wide coping with 4-inch face and back legs. Refer to Appendix 1 to follow the calculation steps. Enter the building identification, date and designer’s initials at the top of the worksheet. Line 02 shows the average building height at the eaves of 100 feet. Enter the coping width on Line 11 and face height on Line 12. This is the basic information needed to determine the forces on the coping. The calculation steps follow: Referring to the Exposure classifications on Page 2 of ES-1, we see that Exposure “B” is appropriate for this hospital. Since a hospital is an essential facility, the Importance Classification is “IV” (Table 1 on Page 3 of ES-1). Circle these selections on lines 03 and 04. Figure 5: Florida high-rise destruction during Hurricane Andrew [courtesy Roger Edwards] © !992 Roger Ed wards Examining the wind speed map on Page 7, note that Lakeland has a Basic Wind Speed of 130 miles per hour. Enter the wind speed on Line 05. Lookup the Importance Factor (Table 3, Page 4), based on the Classification circled on Line 04. The value is 1.15. Enter it on Line 06. Then multiply line 04 by Line 06 to get Line 07, “Design Wind Speed.” Now we are ready to find the Theoretical Velocity Pressure (Table 4 on Page 5). Enter the Table for “Exposure B” (Line 03). A building 100 feet high (Line 02) and a Design Wind Speed of 150 mph (Line 07) gives a Velocity Pressure of 57 psf. Enter 57 on Line 08. Pressure coefficients are obtained from Table 5, Page 6. These coefficients correct the theoretical velocity pressures of Table 4 to actual design pressures. No safety factors are needed here. The pressure coefficients themselves provide the recommended values. Different values are needed for outward force (horizontal) and upward force (vertical). The building exceeds 60 feet, so we use the right hand column values: -1.8 for horizontal and -2.3 vertical. The negative sign denotes that the force is away from the building, tending to tear the edge device off. Enter -1.8 and -2.3 on Line 09. We may ignore the minus sign if we remember that the force is always acting away from the building. Multiply the Theoretical Velocity Pressure (Line 08) by the pressure coefficient (Line 09) to get Design Pressure (Line 10). The pressure is 102.6 psf horizontal and 131.1 psf vertical. Divide Lines 11 and 12 by 12.0 to convert inches to feet. The 4-inch face is 0.33 feet high and the 16-inch coping is 1.33 feet wide. Enter the results on Line 13. The linear resistance we seek is found by multiplying the pressure (pounds per square foot) by the height and width in feet to get pounds per linear foot (33.9 and 174.4) which are entered on Line 14. Test RE-3 (see Page 10) must result in at least 33.9 pounds per foot on the face and 174.4 pounds per foot on the top. Remember that the tests must be performed on a face and the top simultaneously. If the back leg dimension Hickman-4 differs from the face, recalculate Lines 12-13 for the different back-leg height. That result will be the performance demanded of the back leg. The designer may properly place the burden of calculation on the roof edge provider, by simply specifying that the edge comply with ANSI/SPRI ES-1-98. Other Provisions of ES-1-98 The designer may specify a minimum thickness, or simply require the roof edge provider to comply with the Standard. Frequently, dissimilar metals are used for the face and the cleats or retaining devices. Care must be exercised in selecting these materials. Allowable metal pairs are shown on Page 6. Other pairs may be chosen, but only if they can be shown to provide satisfactory galvanic compatibility (Sec. 5.3 p.6). The face of the coping must be wide enough to extend one inch below the top of the wall facing (Sec. 2.4 p.2). This provision of the Standard is to prevent blowing rain from entering the building behind the facing material. If the coping is secured to a nailer, the attachment of the nailer must be sufficient to carry the loads calculated above. This requirement can be especially troublesome in retrofitting, because the condition of the nailer may not be known during the design process. The following examples will be followed in less detail. Refer to the Appendices for calculation results. Example 2, Florida Low-Rise (Worksheet Appendix 2) Assume another Florida building. This time, it is a low-rise motel on the beach near Miami. The specification is for an 8 inch coping with 3 inch face and back leg. Notice that even though the wind zone is fiercer, the requirements are much less stringent. The reasons are: The building is not an “essential facility”; it is not a high-rise; the coping is smaller. Since the building is on the waterfront, it qualifies as an “Exposure D” location. Being a motel, however, it is neither low hazard nor critical. For that reason, it qualifies for Importance Category II. The basic wind speed in Miami, from the map, is 150 mph. These factors lead to 21.0 and 72.4 pounds per ft, roughly half of the design requirements for Example 1. Figure 6: Midwest school roof destroyed after edge failed in storm [courtesy Beavers & Assoc.] Example 3, Midwest Low Rise (Worksheet Appendix 3) Moving away from the hurricane coast, this example is a hotel in Ann Arbor, Michigan. It is set in an urban, low-rise area, so it is “Exposure is B.” Unlike the motel of the previous instance, large numbers of people can congregate in a hotel. Thus, the Importance Category is III, since it is a building that represents substantial hazard to human life in the event of a failure. The fascia for the building must be tested to 24.5 pounds per foot. Furthermore, if the fascia is to retain Hickman-5 the roofing, it must be tested under the RE-1 protocol to have a gripping power of 100 pounds per foot (Test RE-1, p.8). In addition to the face coverage, the designer must be careful to design the edge so that it doesn’t overlap the back of the nailer (see Sec. 5.3, p3). Example 4, Equipment shed (Worksheet Appendix 4) In this example, we have an equipment shed. If it collapsed, there would be scant chance of loss of human life. Its Importance Category, therefore, is I, “buildings that represent low hazard to human life.” Situated on a farm, it has an environment of open terrain with scattered buildings. Clearly, “Exposure C.” Even such a low risk building in America’s “Heartland” requires over 13 pounds per foot of horizontal resistance on the face and 34 pounds uplift. Summary These worked examples can give a sense of the pressure forces that edge systems must resist. The forces developed through these examples require resistances on the faces of the edge devices of from 26.6 psf to 102.6. They require uplift resistances of 34.2 to 131.1 psf. Figure 7: Roof and insulation blown off after edge system failed during Hurricane Hugo [W.P. Hickman Company photo] Hickman-6 IS HICKMAN ® ©1999 W.P. Hickman Company, Appendix 1 ANSI/SPRI ES-1-98 Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems Permission is hereby granted to reproduce this page as The Leading Edge® needed. *Page number of ES-1-98. Line Building Parameters DATA Page* 01 Building Description (City, State, Type of Building, Local Terrain) Hospital By: Lakeland, FL JBH Downtown location Date: 16” Coping w/ 4” Face 3/15/99 02 Building Height at Eave 100 ft 03 Exposure (Based on Local Terrain) Ci rcl e One Page A [ B | C D 2 04 Importance Classification (From Table 1) cLrcle One i i ii i in Page 3 05 Basic Wind Speed (From wind speed map) 130 mph Page 7 06 Importance Factor (Select Factor from Table 3 Based on Line 04 Above. 1.15 Page 4 07 Design Wind Speed = Basic Wind Speed X Importance Factor. 150 mph Design wind speed Wfe– 08 Theoretical Velocity Pressure Choose Table 4 Section Based on Exposure (Line 03). Enter Table 4 with Basic Wind Speed (Line 05) and Building Height (Line 02). 57 Lbs. per sqft Page 6 09 Pressure Coefficient Select from Table 5 based on Building Height (line 02). Hori – zontal Verti -cal -1.8 -2.3 tSBpWJsB 10 Design Pressure (Ignore negative) Multiply Line 08 by Line 09 102.6 PSf 131.1 PSf 11 Width of Top (Omit if Edge Is Not Coping) Wife; 16 inch • ; ‘1 12 Face Height 4 inch 13 Height and Width in Feet (Divide lines 11&12 by 12.0 to convert to feet.) 0.33 Ft 1.33 ft 14 Design Resistance Multiply Line 10 by Line 13. Edge device must be tested to meet or exceed this force. Face Top ifiK .: ■ ‘ll.I11′ 33.9 tbs. /ft outward 174.4 lbs. /ft upward Hickman-7 Appendix 2 ANSI/SPRI ES-1-98 Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems Line Building Parameters DATA Page* 01 Building Description (City, State, Type of Building, Local Terrain) Motel By: Miami Beach JBH Seaside Date: 8” Coping w/ 3” Face 3/15/99 02 Building Height at Eave 45 ft 03 Exposure (Based on Local Terrain) Ci rcl e One Page A B C pT 2 04 Importance Classification (From Table 1) Circle One 1 [ II ] III 1 IV Page 3 05 Basic Wind Speed (From wind speed map) 150 mph Page 7 06 Importance Factor (Select Factor from Table 3 Based on Line 04 Above. 1.00 Page 4 07 Design Wind Speed = Basic Wind Speed X Importance Factor. 150 mph Design Wind Speed 08 Theoretical Velocity Pressure Choose Table 4 Section Based on Exposure (Line 03). Enter Table 4 with Basic Wind Speed (Line 05) and Building Height (Line 02). 60 Lbs. per sqft Page 6 09 Pressure Coefficient Select from Table 5 based on Building Height (line 02). HOM – zontal verti -cal -1.4 -1.8 10 Design Pressure (Ignore negative) Multiply Line 08 by Line 09 84.0 Psf 108.0 Psf 11 Width of Top (Omit if Edge Is Not Coping) X 8 inch : 12 Face Height 3 inch r ^3? 13 Height and Width in Feet (Divide lines 11&12 by 12.0 to convert to feet.) 0.25 Ft 0.67 ft ” 14 Design Resistance Multiply Line 10 by Line 13. Edge device must be tested to meet or exceed this force. Face Top L t U fi 21.0 lbs. /ft I Outward 72.4 lbs. /ft Upward 13 HICKMAN The Leading Edge® ©1999 W.P. Hickman Company, Asheville NC. Permission is hereby granted to reproduce this page as needed. *Page number of ES-1-98. Hickman-8 Appendix 3 ANSI/SPRI ES-1-98 Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems Line Building Parameters DATA Page* 01 Building Description (City, State, Type of Building, Local Terrain) Hotel By: Ann Arbor, MI JBH Urban-Low Rise Area Date: 6” Fascia 3/15/99 02 Building Height at Eave 120 ft 03 Exposure (Based on Local Terrain) Ci rcle One A |b I C D Page 2 04 Importance Classification (From Table 1) circle one I | II j in | IV Page 3 05 Basic Wind Speed (From wind speed map) 90 mph Page 7 06 Importance Factor (Select Factor from Table 3 Based on Line 04 Above. 1.15 Page 4 07 Design Wind Speed = Basic Wind Speed X Importance Factor. 103.5 mph Design wind speed 08 Theoretical Velocity Pressure Choose Table 4 Section Based on Exposure (Line 03). Enter Table 4 with Basic Wind Speed (Line 05) and Building Height (Line 02). 27 Lbs. per sqft Page 6 09 Pressure Coefficient Select from Table 5 based on Building Height (line 02). Hori – zontal verti -cal -1.8 -2.3 10 Design Pressure (Ignore negative) Multiply Line 08 by Line 09 48.6 PSf X PSf 11 Width of Top (Omit if Edge Is Not Coping) wife ’I’. ■ : ■’ ■ . •H i’ X inch ills /pii 12 Face Height 6 inch 13 Height and Width in Feet (Divide lines 11&12 by 12.0 to convert to feet.) 0.50 Ft X Ft ft”’ * «• 14 Design Resistance Multiply Line 10 by Line 13. Edge device must be tested to meet or exceed this force. Face Top 24.3 lbs. /ft outward X lbs. /ft upward 13 HICKMAN The Leading Edge® ©1999 W.P. Hickman Company, Asheville NC. Permission is hereby granted to reproduce this page as needed. *Page number of ES-1-98. Hickman-9 Appendix 4 ANSI/SPRI ES-1-98 Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems _ Line Building Parameters DATA Page* 01 Building Description (City, State, Type of Building, Local Terrain) Equipment Shed By: Farm near St. Louis, MO JBH Agricultural Date: 12” Coping w/ 6” Face 3/15/99 02 Building Height at Eave 32 ft 03 Exposure (Based on Local Terrain) Ci rcl e One A B [ cj D Page 2 04 Importance Classification (From Table 1) Ci rcl e One Page I 1 II 1 III 1 IV 3 05 Basic Wind Speed (From wind speed map) 90 mph Page 7 06 Importance Factor (Sei 04 Above. ect Factor from Table 3 Based on Line 0.87 Page 4 nportance Factor. 78 mph Design wind speed Of 11 07 Design Wind Speed = Basic Wind Speed X Ir 08 Theoretical Velocity Pressure Choose Table 4 Section Based on Exposure (Line 03). Enter Table 4 with Basic Wind Speed (Line 05) and Building Height (Line 02). 19 Lbs. per sqft Page 6 09 Pressure Coefficient Select from Table 5 based on Building Height (line 02). Hori – zontal verti -cal -1.4 -1.8 .’. ‘v 10 Design Pressure (Ignore negative) Multiply Line 08 by Line 09 26.6 PSf 34.2 PSf 11 Width of Top (Omit if Edge Is Not Coping) l-aa.’.’- 12 inch -IZA*; ? BOSOr 12 Face Height 6 inch 13 Height and Width in Feet (Divide lines 11&12 by 12.0 to convert to feet.) 0.50 Ft 1.00 ft /I® 14 Design Resistance Multiply Line 10 by Line 13. Edge device must be tested to meet or exceed this force. Face Top – c – > 13.3 lbs. /ft Outward 34.2 lbs. /ft Upward IKI® ®^99 W.P. Hickman Company, Asheville NC. HI 1^.1 V 1 /Kill Permission is hereby granted to reproduce this page as The Leading Edge® needed. *Page number of ES-1-98. Hickman- 10 IS HICKMAN ® ©1999 W.P. Hickman Company, Asheville NC. Appendix 5 ANSI/SPRI ES-1-98 Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems @ Permission is hereby granted to reproduce this page as Th© Leading Edgo needed. *Page number of ES-1-98. Line Building Parameters DATA Page* 01 Building Description (City, State, Type of Building, Local Terrain) By: Date: 02 Building Height at Eave ft 03 Exposure (Based on Local Terrain) Ci rcl e One Page A B C 1 D 2 04 Importance Classification (From Table 1) Ci rcle One Page i 3 11 III | IV 05 Basic Wind Speed (From wind speed map) mph Page 7 06 Importance Factor (Select Factor from Table 3 Based on Line 04 Above. Page 4 07 Design Wind Speed = Basic Wind Speed X Importance Factor. mph Design wind speed 08 Theoretical Velocity Pressure Choose Table 4 Section Based on Exposure (Line 03). Enter Table 4 with Basic Wind Speed (Line 05) and Building Height (Line 02). Lbs. per sqft Page 6 09 Pressure Coefficient Select from Table 5 based on Building Height (line 02). HOM – zontal verti – cal 10 Design Pressure (Ignore negative) Multiply Line 08 by Line 09 psf Psf 11 Width of Top (Omit if Edge Is Not Coping) r inch 12 Face Height inch 13 Height and Width in Feet (Divide lines 11&12 by 12.0 to convert to feet.) Ft Ft 14 Design Resistance Multiply Line 10 by Line 13. Edge device must be tested to meet or exceed this force. Face Top lilll 1bs ./ft Outward tbs. /ft Upward Hickman- 11 Approved November 10, 1998 ANSl/SPRI ES-1-98 . American National Standard Wind Design Standard for Edge Systems Used with Low Slope Roofing Systems 1 INTRODUCTION (See Commentary: 1) The following standard is a reference for those who design, specify or install edge materials used with low slope roofing systems. Although it does address corrosion, this Standard focuses primarily on design for wind resistance. It is in¬ tended for use with the specifications and re¬ quirements of the manufacturers of the specific roofing materials and the edge systems used in the roofing assembly, excluding gutters. The membrane manufacturer shall be consulted for specific recommendations for making the roof watertight at the edge. This design standard addresses copings and horizontal roof edges, and the following factors shall be considered in designing a roof edge. • Structural integrity of the substrate that an¬ chors the edge • Wind resistance of the edge detail • Materials specifications 2 GENERAL DESIGN CONSIDERATIONS AND DEFINITIONS (See Commentary: 2) All materials for roof edge construction shall have sufficient strength to withstand the design wind load. The following factors apply when de¬ signing a roof edge system: Wind speed, build¬ ing height, corner and perimeter regions, edge condition, Exposure Factor, topography, galvanic compatibility and Importance Factor. 2.1 WIND SPEED (See Commentary: 2.1) Basic wind speed values used in the design cal¬ culations are 3-second gust speeds in miles per hour (m/s) measured at 33 ft (10 m) above ground for Exposure Factor C associated with an annual probability of 0.02 (50 year return). American national Standards Institute | These values are taken from the ANSI/ASCE 7-95 1 document (See attachment I) or the au¬ thority having jurisdiction. Section 6.5.5 of ASCE 7-95 1 shall be used to adjust design wind speed for the intensifying effects of valleys and other unique topographic features such as hills or escarpments. (See Commentary: 2.1 ) The au¬ thority having jurisdiction shall be contacted for verification of wind data. 2.2 BUILDING HEIGHT The building height shall be measured from ground level to the mean height of the roof sec¬ tion under design. 2.3 ROOF EDGE REGIONS Wind forces near the corner regions are of greater intensity than in the perimeter regions between corners. These regions are defined as follows: 2.3.1 CORNER REGION For buildings with mean roof height up to 60 feet (18 m), the corner region is a distance from the building corner that is 10% of the minimum build¬ ing width or 40% of the building height at the eaves, whichever is smaller, but not less than 4% of the minimum building width and not less than 3 feet (0.9 m). For buildings with mean roof height greater than 60 feet (18 m), the cor¬ ner region is a distance from the building cor¬ ner that is 10% of the minimum building width but not less than 3 feet (0.9 m). Copyright © 1998 by SPRI, 200 Reservoir Street, Needham, MA 02494. All Rights Reserved. 1 ANSI/SPRI ES-1-98 Approved November 10, 1998 Figure 1: Edge Flashing Coverage 2.3.2 PERIMETER The perimeter is the section of roof edge be¬ tween corner regions as defined in Section 2.3.1 (above). 2.4 EDGE CONDITION (See Commentary: 2.4) The edge condition includes the roof edge de¬ vice (edge flashing or coping) and the nailer or other substrate to which the edge device is at¬ tached. Coverage is the location of the lowest vertical point of the roof edge device or any extension of it, exclusive of any drip bend or other protru¬ sion. The coverage shall extend a minimum of 1 inch (25 mm) below the bottom of the nailer. The roof membrane shall not extend below the coverage. 2.5 EXPOSURE (See Commentary: 2.5) The building shall be classified into one of the following Exposures based on surrounding ter¬ rain: 2.5.1. EXPOSURE A. Large city centers with at least 50% of the build¬ ings having a height in excess of 70 feet (21 .3 m). Use of this exposure category shall be lim¬ ited to those areas for which terrain represen¬ tative of Exposure A prevails in the upwind di¬ rection for a distance of at least one-half mile (0.8 km) or 10 times the height of the building or other structure, whichever is greater. Possible channeling effects or increased velocity pres¬ sures due to the building or structure being lo¬ cated in the wake of adjacent buildings shall be taken into account. 2.5.2. EXPOSURE B. Urban and suburban areas, wooded areas, or other terrain with numerous closely spaced ob¬ structions having the size of single-family dwell¬ ings or larger. Use of this exposure category shall be limited to those areas for which terrain representative of Exposure B prevails in the up¬ wind direction for a distance of at least 1,500 feet (460 m) or 10 times the height of the build¬ ing or structure, whichever is greater. 2.5.3. EXPOSURE C. (See Commentary: 2.5.3) Open terrain with scattered obstructions having heights generally less than 30 feet (9.1 m). This category includes flat open country and grass¬ lands. 2.5.4. EXPOSURE D. Flat, unobstructed areas exposed to wind flow¬ ing over open water for a distance of at least 1 mile (1.61 km). This exposure shall apply only to those buildings and other structures exposed to the wind coming from over the water. Expo¬ sure D extends inland from the shoreline a dis¬ tance of 1,500 feet (460 m) or 10 times the height of the building or structure, whichever is greater. 2.6 IMPORTANCE FACTOR (See Commentary: 2.6) Buildings fitting one of the following criteria shall have an “Importance Factor* included in the wind design calculations. Table 1 (page 3) explains these building classifications. Refer to Section 5.1 and Table 3 for use of Importance Factor. 2 Approved November 10, 1998 ANS1/SPRI ES-1-98 TABLE 1 IMPORTANCE FACTOR CLASSIFICATION OF BUILDINGS AND OTHER STRUCTURES FOR WIND, SNOW, AND EARTHQUAKE LOADS : ’ * rux. a j _-u– ~ -n —- _->t-_ 1 V .k— Sar – ‘k_ Xi * J: . ■ ri J jk * Nature of Occupancy Category Buildings and other structures that represent a low hazard to I human life in the event of failure including, but not limited to: • Agricultural facilities • Certain temporary facilities • Minor storage facilities All buildings and other structures except those listed In Categories I, III, IV II Buildings and other structures that represent a substantial hazard to human III life In the event of failure including, but not limited to: • Buildings and other structures where more than 300 people congregate in one area • Buildings and other structures with elementary school, secondary school, or day-care facilities with capacity greater than 250 • Buildings and other structures with a capacity greater than 500 for colleges or adult education facilities • Health care facilities with a capacity of 50 or more resident patients but not having surgery or emergency treatment facilities • Jails and detention facilities • Power generating stations and other public utility facilities not included in Category IV • Buildings and other structures containing sufficient quantities of toxic or explosive substances to be dangerous to the public if released Buildings and other structures designated as essential facilities Including, but not limited to: IV • Hospitals and other healthcare facilities having surgery or emergency treatment facilities • Fire, rescue and police stations and emergency vehicle garages • Designated earthquake, hurricane, or other emergency shelters • Communications centers and other facilities required for emergency response • Power generating stations and other public utility facilities required in an emergency • Buildings and other structures having critical national defense functions From ASCE 7/951 3 SYSTEM REQUIREMENTS (See Commentary: 3) 3.1 NAILER SECURED SYSTEMS The basic attachment of the nailer shall be suf¬ ficient to carry the design wind uplift load and the load specified in Section 4.1. At outside building corners regions8, nailer securement shall be designed to carry a load two times the basic nailer attachment design load. Wood nailers shall be minimum thickness 1.5 inch (38 mm). For devices used to secure the roofing (e.g., gravel stops), the nailer shall extend at least 1/2 inch (13 mm) beyond the back edge of the horizontal flange of the roof edge device. The following fastener safety factors shall be applied to design loading. a See section 2.3 for definitions of corner regions. 3 ANSl/SPRI ES-1-98 Approved November 10, 1998 4 DESIGN OPTIONS (See Commentary: 4) Table 2 Substrate Wind Load Safety Factor Wood2 4.5 Masonry3 3.0 Steel4 1.9 The following minimum securement criteria ap¬ ply for edging systems. When building codes re¬ quire higher wind resistance, the designer shall calculate and design for the required loads ac¬ cording to local building codes. 4.1 MEMBRANE ATTACHMENT (See Commentary: 4.1) Except for Built-Up or fully adhered modified bi¬ tumen roofing, the design of the perimeter at¬ tachment, when terminating the roofing system, shall provide a minimum holding power of 100 pounds/foot (1 .46 kN/m) holding power. This force shall be measured in a direction of 45 de¬ grees back onto the roof as tested according to SPRI Test Method RE-1 (attached). Specifically for mechanically attached membrane roofing systems, the perimeter attachment loadings shall be calculated based on the force required to hold the roof system’s perimeter sheet in place for the design wind speed. The fastener spacing shall be adjusted and the edge detail shall have sufficient strength to meet and resist these loads. 4.2 WIND RESISTANCE OF EDGE FLASHING (Gravelstop) (See Commentary: 4.2 & 4.3) The vertical face of edge flashing shall be tested according to SPRI Test RE-2 (attached). Test results shall meet or exceed design wind pres¬ sures as calculated according to RE-2. 4.3 WIND RESISTANCE OF COPING (See Commentary: 4.2 & 4.3) Copings shall be tested according to SPRI Test Method RE-3 (attached). Test results shall meet or exceed horizontal and vertical design wind pressures as calculated according to RE-3. 4.4 FASTENER SPACING Fastener densities providing satisfactory results in SPRI Tests RE-2 and RE-3 shall be increased by a factor of two at corner regions (as defined in Section 2.3.2) to allow for increased velocity pressure in these regions. 5 DESIGN PROVISIONS (See Commentary: 5) 5.1 WIND DESIGN (See Commentary: 5.1) The roof edge design pressure (P) shall be cal¬ culated using the formula P = GCp x qz x I x kzt in which: P = Design Pressure, GCP = Gust Factor times Pressure Coeffi¬ cient, hereafter referred to simply as Pressure Coefficient, qz = Velocity Pressure at building height, z kzt = Topographic Factor (=1 .0 for flat terrain, see ASCE 7-95, p. 20 for other terrain) and I = Importance Factor Multiplier. The basic wind speed shall be determined from Attachment I or the authority having jurisdiction. Velocity Pressure, “qz” shall be obtained from Table 4 corresponding to the appropriate Expo¬ sure (see Section 2.5) and the basic wind speed. Where the design speed, adjusted for topo¬ graphic effects, exceeds 150 miles per hour (237 km/h) or when building height exceeds 150 feet (45 m), velocity pressure shall be calculated according to Equation 6-1 from ASCE 7-95. The importance factor, “I”, shall be obtained us¬ ing Table 3: ASCE 7-95 1 p. 17. TABLE 3 IMPORTANCE FACTOR Building Category Importance (See Table 1 .Section 2.6 Factor of this Design Standard) 1 1 0.87 II 1.00 III 1.15 IV 1.15 4 Approved November 10, 1998 ANSUSPRI ES-1-98 TABLE 4 Velocity Pressure (qz) Exposure A Exposure B ‘ – Building > \ -‘ “Maximum Wind Spe^;*^ 5<* A A A”; Height s-85s – 90/XxTAIOD^A ^^50 ’ – ‘”’A ‘A mph \X‘ mph;/i mph mph mph . mph 0-60 ft Use Exposure “C” >60 -80 ft 12 13 16 19 23 27 31 36 >80 – 100 ft 13 14 17 21 25 29 34 39 >100 – 125 ft 14 15 19 23 27 32 37 43 >125 – 150 ft 15 17 20 25 29 35 40 46 Exposure C Building Maximum Wind Speed Height 85 90 ,. 100 110 120 130 140 .150′ mph mph mph mph mph mph mph mph 0-60 ft Use 85% of Loads for Exposure “C” >60 -80 ft 17 19 24 29 34 40 47 53 >80 -100 ft 18 20 25 31 36 43 50 57 >100 – 125 ft 19 22 27 33 39 46 53 61 >125 – 150 ft 21 23 28 34 41 48 56 64 Exposure D Building Maximum Wind Speed Height 85 90 100 110’ 120 130 140 150 mph mph mph mph mph mph mph mph 0-20 ft 17 19 23 28 33 39 45 52 >20 -40 ft 19 22 27 32 38 45 52 60 >40 – 60 ft 21 24 29 35 42 49 57 65 >60 – 80 ft 22 25 31 37 45 52 61 70 >80 – 100 ft 23 26 32 39 47 55 64 73 >100 -125 ft 25 28 34 41 49 57 67 76 >125 – 150 ft 25 29 35 43 51 60 69 79 Building Maximum Wind Speed Height 85 90 100 110 120 130 140 . 150 mph mph mph – mph ■ mph . imph mph \ mph 0-60 ft Use Exposure “C” >60 – 80 ft 25 29 35 43 51 60 69 79 >80 – 100 ft 27 30 37 44 53 62 72 83 >100 – 125 ft 28 31 38 46 55 64 75 86 >125 – 150 ft 28 32 39 48 57 67 77 89 5 ANSI/SPRI ES-1-98 Approved November 10, 1998 Tables Pressure Coefficient-Gust Factor Product, GCp Buildings Buildings 60 feet high over or less 60 feet high Horizontal GCP (acting outward from the building face) -1.4 -1.8 Vertical GC„ (acting upward at the building edge) -1.8 -2.3 The Pressure Coefficient, “GCP” shall be obtained from Table 5: (See Commentary 5.1 ) In Table 5, the negative sign (-) means that the pressure is away from the building, tending to pull materials up or off. Roof edge designs shall pass tests RE-1 , RE-2 and RE-3 as appropriate for the application: Edge de¬ vices designed to act as membrane terminations shall pass SPRI Test RE-1 . Edge flashings and other edge devices for which the exposed vertical component area exceeds the ex-posed horizontal component area (edge flashings, etc.) shall pass SPRI Test RE-2. Copings and other devices for which the exposed horizontal area exceeds the exposed vertical area shall pass SPRI Test RE-3. To allow for higher wind loads at corners, double the fastening in the cor¬ ner region instead of testing corner assemblies when the straight length assembly passes RE-3. Exposed areas in the above requirements shall be those elements upon which the wind forces act di¬ rectly. 5.2 METAL THICKNESS (See Commentary: 5.2) Minimum gauges for exposed faces5 shall be de¬ termined from Table 6: 5.3 GALVANIC COMPATIBILITY AND RESISTANCE (See Commentary: 5.3) Metal edge devices (face, clip and fastener) shall be of the same kind of metal, or shall be gal¬ vanically compatible metal pairs. Compatible metal pairs shall be selected from the following list: Aluminum-Galvanized Steel Aluminum-Stainless Steel Copper-Stainless Steel or other pairs that can be shown to provide sat¬ isfactory galvanic compatibility. Copper shall not be used In combination with steel, zinc or aluminum. Fasteners shall be galvanically compatible with the other roof edge system components. 5.4 APPLIANCES Appliance attachments, such as lightning rods, signs or antennae that penetrate the water seal, induce a galvanic reaction or otherwise compro¬ mise the effectiveness of the roof edge system, shall be eliminated or isolated to prevent prob¬ lems. TABLES Minimum Metal Thicknesses for Flatness Exposed Face Galvanized Steel Cold Rolled Copper Formed Aluminum Up to 4“ (to 100 mm) 26 ga (0.022″ 0.6 mm) 16 oz (0.022″ 0.6 mm) 0.040″ 0.8 mm >4″ -8″ (>100-200 mm) 24 ga (0.028″ 0.7 mm) 16 oz (0.022″ 0.6 mm) 0.050″ 1.3 mm >8″ -10″ (>200 – 250 mm) 22 ga (0.034″ 0.9 mm) 20 oz (0.027″ 0.7 mm) 0.063″ 1.6 mm >10″ -16″ (>250 – 400 mm) 20 ga (0.040″ 1.0 mm) ‘■ 0.080″ 2.8 mm 6 Approved November 10, 1998 ANSI/SPRI ES-1-98 7 ANSI/SPRI ES-1-98 Approved November 10, 1998 SPRITest Method RE-1 Test for Roof Edge Termination of BALLASTED OR MECHANICALLY ATTACHED ROOFING MEMBRANE SYSTEMS (See Commentary: SPRI Test Method RE-1) The termination shall withstand a minimum force of 100 Ibs/ft (134 kg/m) according to Section 4.1 of the Standard when tested using the following method. A minimum 12 inch (300 mm) wide mock-up of the termination system shall be constructed and mounted on the base of a tensile testing device so the membrane is pulled at a 45° angle to the roof deck to simulate a billowing membrane (see Fig¬ ure 3). For devices in which fasteners are part of the membrane securement, at least two such fas¬ teners shall be included in a balanced sample. The jaws of the tester shall be connected to two bars that clamp the membrane securely between them so that the load is distributed uniformly along the width of the membrane (see Figure 3). The tester is loaded until failure occurs. Failure is de¬ fined as any event that allows the membrane to come free of the edge termination or the termina¬ tion to come free of its mount. The roof edge ter¬ mination strength is deemed satisfactory if the test force at failure on a 12 inch (300 mm) wide sample meets or exceeds 100 pounds per foot (1 50 kg/m). 8 Approved November 10, 1998 ANSI/SPRI ES-1-98 SPRI Test Method RE-2 Pull-Off Test for Edge flashings (See Commentary: SPRI Test Method RE-2) 1. Apparatus The description of the apparatus is general in nature. Any equipment capable of performing the test procedure within the allowed tolerances shall be permitted. A schematic drawing of this apparatus is shown in Figure 4. The test appa¬ ratus shall be constructed so that the perfor¬ mance of individual components is unaffected by edge or end constraints on the test sample. 2. Safety Precautions Proper precautions shall be taken to protect the operating personnel and observers in case of any failure. 4. Procedure 4.1 Gravity Any undue influence from gravity that does not occur during actual installation shall be omitted from the test specimen. If the test specimen is inverted, a gravity correction shall be made in the determination of the allowable superimposed loading. Tests run in an inverted position shall include data from pressure reversal or an upright specimen to show that unlatching at the drip edges will not occur in the normal orientation. 4.2 Stabilization Fascia Blow-Off Test Set Schematic (Force at Failure x Face Area = Blowoff Resistance) Fascia Figure 4: Fascia Test Schematic 3. Test Specimens All parts of the test specimen shall be full size in width and all other dimensions, using the same materials, details and methods of con¬ struction and anchoring devices (such as clips or cleats) as used on the actual building. Sample length shall be the average length de¬ signed for field use on the project with a mini¬ mum of 8 feet (2.4 m). When the longest length designed for the project is less than 8 feet (2.4 m) the longest design length shall be used. When the anchoring means at the ends of the edge flashing are normally used to restrain other additional lengths of edge flashing, then the an¬ choring means shall be modified so that only that percentage that might restrain rotational movement in the test specimen is used. A dial gauge shall be attached to the centerline of each loaded surface to detect movement. Stabilization of the test shall be when the gauge ceases to show movement. 4.3 Loading Loading shall be applied uniformly on centers no greater than 12″ (300 mm) to the vertical face of the edge flashing. Loading shall be applied on the horizontal centerline of the face. Loads shall be applied incrementally and held for not less than 60 seconds after stabilization has been achieved at each incremental load. Between incremental loads, the loading shall be reduced to zero until the specimen stabilizes, or for five minutes, whichever happens first. After a recov¬ ery period of not more than five minutes at zero load, initiate the next higher incremental load. Loading to the face of the edge flashing shall be applied in increments not to exceed 25 Ib/sq. ft. (120 kg/m2) until approximately 60 Ib/sq. ft. (300 kg/m2) is obtained. Thereafter, increments of load shall not exceed 10 Ib/sq. ft. (5 kg/m2). Loading speed shall be such that each incre¬ mental load up to and including 60 Ib/sq. ft. (300 kg/m2) shall be achieved in 60 seconds or less. Above 60 Ib/sq. ft. (300 kg/m2), incremental load¬ ing shall be aohieved in 120 seconds or less. Loading shall proceed as indicated until the test specimen either fails or exceeds the required design pressure. The increments of load appli¬ cation shall be chosen so that a sufficient num¬ ber of observations are made to determine the exact load at failure. The last sustained 60-second load without failure is the maximum load recorded as the design value. 9 ANSl/SPRI ES-1-98 Approved November 10, 1998 4.4 Failure: Failure shall be loss of securement of any com¬ ponent of the roof edge system. 4.5 Test Results The total force at the conditions described in 4.3 above shall be recorded. This force shall be converted to pressure by dividing the force by the area of the face: Force is measured in Pounds Outward Force Pressure = – — – Face Height x Face Length Force, Length is the test sample length in feet, Height is in Feet (inches/12), Pressure is in Pounds per Square Foot. If test results exceed the design outward wind pressure, the edge flashing has acceptable wind blow-off resis¬ tance. SPRITest Method RE-3 Pull-Off Test for Copings (See Commentary: SPRI Test Method RE-3) 1. Apparatus This description of the apparatus is general in nature. Any equipment capable of performing the test procedure within the allowed tolerances shall be permitted. A schematic drawing of this apparatus is shown in Figures 5 and 6. The test apparatus shall be constructed so that the per¬ formance of individual components is unaffected by edge or end constraints on the test sample. Figure 5: Coping Bi-Directional Test Schematic: Top and Face Leg. 2. Safety Precautions Proper precautions shall be taken to protect the operating personnel and observers in case of any failure. 3. Test Specimens All parts of the test specimen shall be full size in width and all other dimensions, using the same materials, details and methods of con¬ struction and anchoring devices (such as clips or cleats) as used on the actual building. Sample length shall be the average length de¬ signed for field use on the project with a mini¬ mum of 8 feet (2.4 m). When the longest length designed for the project is less than 8 feet (2.4 m) the longest design length shall be used. When the anchoring means at the ends of the edge flashing are normally used to restrain other additional lengths of edge flashing, then the an¬ choring means shall be modified so that only that percentage that might restrain rotational movement in the test specimen is used. 4. Procedure 4.1 Gravity Any undue influence from gravity that does not occur during actual installation shall be omitted from the test specimen. If the test specimen is inverted, a gravity correction shall be made in the determination of the allowable superimposed loading. Tests run in an inverted position shall include data from pressure reversal or an upright specimen to show that unlatching of the drip edges at the cleats will not occur in the normal orientation. 4.2 Stabilization A dial gauge shall be attached to the centerline of each loaded surface to detect movement. Stabilization of the test shall be when the gauge ceases to show movement. 10 Approved November 10, 1998 ANSI/SPRI ES-1-98 4.3 Loading Face and top loadings shall be applied simulta¬ neously in the ratio of (Face Height x Horizon¬ tal Cp) to (Top Width x Vertical Cp) in which the Face Height is the height of the face (front or back leg) being tested. Loading shall be applied uniformly on centers no greater than 12″ (300 mm) to the top of the coping and to one of the faces of the coping at the same time. Loads shall be applied on parallel horizontal centerlines of the surfaces tested. Loads shall be applied incrementally and held for not less than 60 sec¬ onds after stabilization has been achieved at each incremental load. Between incremental loads, the loading shall be reduced to zero until the specimen stabilizes, or for five minutes, whichever happens first. After a recovery pe¬ riod of not more than five minutes at zero load, initiate the next higher incremental load. Load¬ ing to the top of the coping shall be applied in Figure 6: Coping Bi-Directional Test Schematic: Top and Back Leg. increments not to exceed 25 Ib/sq. ft. (120 kg/ m2) until approximately 150 Ib/sq. ft. (730 kg/m2) is obtained. Thereafter, increments of load shall not exceed 10 Ib/sq. ft. (5 kg/m2). Loading speed shall be such that each incremental load up to and including 150 Ib/sq. ft. (730 kg/m2) shall be achieved in 60 seconds or less. Above 150 lb/ sq. ft. (730 kg/m2), incremental loading shall be achieved in 120 seconds or less. Loading shall proceed as indicated until the test specimen either fails or exceeds the required design pressure. The increments of load appli¬ cation shall be chosen so that a sufficient num¬ ber of observations are made to determine the exact load at failure. The last sustained 60-second load without failure is the maximum load recorded as the design value. Both face and back legs shall be tested in this manner. Separate test samples shall be used for testing the face and back legs: One sample to test the face while loading the top (See Fig¬ ure 5), and the other to test the back leg while loading the top (See Figure 6). 4.4 Failure Failure shall be loss of securement of any com¬ ponent of the roof edge system. 4.5 Test Results The total of upward and outward forces at the conditions described in 4.3 above shall be re¬ corded. Each total force shall be converted to pressure by dividing the force by the area of the surface upon which it acts: Outward Pressure = Outward Force Face Height x Face Length Upward Pressure = Upward Force Coping Width x Coping Length Pressure is measured in pounds per square foot, • Force is measured in Pounds Force, • Length is the test sample length in feet, • Height is in Feet (inches/12). • “Face” refers to back leg or front leg of the cop¬ ing specimen. If the test results meet or exceed the design up¬ ward and outward wind pressures on both front and back leg tests, the coping has acceptable wind blow-off resistance. 11 ANSI/SPRI ES-1-98 Approved November 10, 1998 COMMENTARY to WIND DESIGN STANDARD for EDGE SYSTEMS USED with LOW SLOPE ROOFING This Commentary consists of explanatory and supplementary material designed to help design¬ ers, roofing contractors and local building authori¬ ties in applying the requirements of the preceding Standard. This Commentary is intended to create an under¬ standing of the requirements through brief expla¬ nations of the reasoning employed in arriving at these requirements. The sections of this Commentary are numbered to correspond to sections of the Standard to which they refer. Since having supplementary material for every section of the Standard is not necessary, not all sections are referenced in this Commentary. 1 INTRODUCTION This Design Standard was developed for use with Built-Up (BUR), Single-Ply and Modified Bi¬ tumen roofing systems. While the Standard is intended as a reference for designers and roof¬ ing contractors, the design responsibility rests with the “designer of record.” Roof edge systems serve aesthetic as well as performance functions for a building. Aestheti¬ cally, they provide an attractive finish and some¬ times even a key feature to the exterior of a building. Of course, no matter how aesthetically pleasing, a roof edge system must act primarily as an effective mechanical termination and tran¬ sition between the roof and other building com¬ ponents such as parapet walls, vertical walls, corners, soffits, edge flashing boards, etc. A high performance roof edge system provides many benefits. It acts as a water seal at the edge. When it is also the means by which the membrane is attached to the building at the edge, it must also exhibit sufficient holding power to prevent the membrane from pulling out at the edge under design wind conditions. Fur¬ thermore, the edge system itself must not come loose in a design wind. A loose edge system not only endangers surrounding property or per¬ sons, but it also exposes the roofing to blow-off, starting at the edge. Perimeter systems considered for this Standard are differentiated into two general types: EDGE FLASHINGS: These are products or de¬ signs that complete the horizontal deck or mem¬ brane plane at its transition to a vertical wall drop, typically at a 90° angle. Normally the roof¬ ing membrane is restrained by the edge by means of a mechanical gripping of the roofing between metal flanges or by a bond between the roofing and edging. Termination devices against vertical walls in¬ board of the roof edge are not considered by this Guideline. GUTTERS: Gutters and other rain-carrying de¬ vices are beyond the scope of this Standard. However, the designer should be aware that their securement is important to the proper func¬ tioning of the building. Two general classes of materials cover nearly all perimeter systems. They are: EXTRUSIONS: Shapes or designs made by forcing heated metal or polymeric material through pre-cut custom dies. These designs are usually of a heavier gauge than formed prod¬ ucts, but many extrusions must have their fin¬ ish applied after manufacturing. FORMED METAL: Sheets of metal, usually steel, aluminum or copper, bent on press brakes or roll-forming equipment to match a desired de¬ sign or configuration. Available in many thick¬ nesses and frequently with a variety of finishes. MAINTENANCE The design engineer should consider maintenance of the roof edge. See the ARMA/NRCA/SPRI Re¬ pair Manual for Low-Slope Roof Membrane Sys¬ tems6. SUMMARY This document addresses factors that should be considered in the specification and design of roof edge systems for low slope roofing systems. Good design practice requires consideration of nailer, roof edge and membrane securement, and also selec¬ tion of materials and finishes to minimize corrosion, and metal gauges to assure strength and flatness. 12 COPINGS/CAPS: These are designs that cover the tops of parapet walls, usually with the roof¬ ing membrane terminated under them. Approved November 10, 1998 ANSI/SPRI ES-1-98 COMMENTARY 2 GENERAL DESIGN CONSIDERATIONS AND DEFINITIONS Determination of the appropriate wind force cat¬ egory shall be based on wind speed, Exposure, building height, topography and the edge detail location on the building. Location of the edge detail on the building is also important, since blow-off forces increase near the corners. 2.1 WIND SPEED Special wind regions (mountains or valleys): Refer to Section 6.5.5 of the ANSI/ASCE 7-951 Commentary. The intensifying effects of topography (hills or escarpments) are to be accounted for. Speedup over hills and escarpments is accounted for in ASCE 7-95 by means of a topographic factor, k^ that depends on the height of the building, the height and slope of the hill or escarpment, the distance of the crest upwind of the building, and whether the terrain is a hill or an escarp¬ ment. 2.3 CORNER REGION The angle at which the walls meet to constitute a corner is undefined here and in ASCE 7-95. It has been suggested that an airflow separa¬ tion effect begins to take effect when walls meet at 150°. Therefore, since most walls meet at angles more acute than this, the meeting angle in not a practical consideration for this Stan¬ dard7. 2.4 EDGE CONDITION The roof edge may also function as an air seal, when combined with an air-retarder throughout the field of the roof, by preventing air infiltration under the roofing membrane. To resist air infil¬ tration, nailers should be sealed to the building with appropriate sealant materialb. Where mul¬ tiple courses of nailers are used, these nailer courses should also be sealed to each other. Butt-joints should also be sealed. 2.5 EXPOSURE 2.5.3 EXPOSURE C Consistent with ASCE 7-95, the Standard uses Exposure “C” for all buildings with heights 60 ft. (18 m) or less. For building heights of 60 feet or less in Exposure “B,” use 15% lower load than for Exposure “C.” 2.6 IMPORTANCE FACTOR The Importance Factor, I, accounts for the de¬ gree of hazard to human life and damage to property. The Importance Factor, I, is used to modify the wind speed and, in effect, assign dif¬ ferent levels of risk based upon intended use of the structure. Category I Exposure gives a 25 year mean recurrence value while Categories III and IV give 100 year mean recurrence values. Other recurrence values can be found in the Commentary of ASCE 7-951. 3 SYSTEM REQUIREMENTS Resistance to blow-off depends not only upon the attachment of the roof edge device to the edge of the building, but also upon the integrity of the nailer or other substrate to which the edge device is attached. It is important to consider the load path from the nailer to the foundation of the building to assure proper wind load pro¬ tection. Table? Substrate Safety Factor Static Load Wind Load Wood8 6.0 4.5 Masonry9 4.0 3.0 Steel 10 2.5 1.9 Common fastener safety factors follow. Note that when designing for wind, static load safety factors may be reduced by 25%. WOOD MEMBERS The terrain surrounding a building will influence the exposure of that building to the wind. Nailers should be pressure treated wood11 se¬ cured by corrosion resistant12 anchor bolts coun¬ tersunk into the wood nailer and attached to the nailer with nuts and washers. Anchor bolts should be of sufficient size and spacing to rebAn appropriate sealant is a single or multi-component elastomeric material used to weatherproof construction joints. 13 ANSl/SPRI ES-1-98 Approved November 10, 1998 COMMENTARY sist the design load and a minimum 200 Ibf/ft (300 kg/m) vertical load. For wood nailers wider than 6″ (152 mm), bolts should be staggered to avoid splitting the wood. Each wood nailer member should have at least two fasteners. A fastener should be located approximately 4“ (100 mm) and minimum 3″ (75 mm) from each end of the wood. Additional wood members, such as edge flashings, cant strips and stacked nailers should be fastened with corrosion resis¬ tant fasteners having sufficient pullout resis¬ tance. Fasteners should be staggered, spaced at a maximum 12 inches (305 mm) on centers, and should penetrate the wood sufficiently to achieve design pullout resistance. Spacing should be on maximum 6 inches (152 mm) cen¬ ters in corner regions0. MASONRY When imbedded in masonry, anchor bolts as de¬ fined above should be bent 90° at the base or have heads designed to prevent rotation and slipping out. When hollow block masonry is used at the roof line, cores and voids in the top row of blocks should be filled with concrete hav¬ ing a minimum density of 140 Ibs/cu ft (10,900 g/m3 ). When imbedded in light aggregate block, bolts should be embedded minimum 12 inches (300 mm) into concrete fill. When heavy aggre¬ gate blocks are used, bolts should be embed¬ ded minimum 8 inches (200 mm). LIGHTWEIGHT CONCRETE AND GYPSUM DECKS Nailers should not be fastened to light weight concrete or gypsum decks. Instead, anchor nailers directly to wall structural members using fasteners whose size and locations meet the Standard under 3.1 above. STEEL DECK The steel deck should be designed to withstand the design forces specified under 3.1. Nailer at¬ tachment should be strong enough to resist 200 Ibf/ft (300 kg/m) vertical load. NAILERLESS SYSTEMS When the roof edge is attached directly to ma¬ sonry or steel without the use of a nailer, its at¬ tachment configuration should be tested to re¬ sist wind loading, using tests specified in Sec¬ tion 4 of this Standard. REROOFING For nailer security when reroofing, the contrac¬ tor should check to be sure the nailer or other substrate is in good condition and well secured to the building. Questionable members should be removed and replaced according to the above guidelines. Note that it is much more dif¬ ficult to be sure that the load path (connection of roof members ultimately to the building foun¬ dation) is secure for an existing building than it is for new construction. The roofing contractor should notify the designer if unexpected condi¬ tions or deteriorated substrate materials are dis¬ covered during the reroofing process. 4 DESIGN OPTIONS Holding power of the edge detail is divided into two considerations. The first is the resistance of the edge to outward and upward forces that tend to blow or peel the edge system off the substrate. The second is the ability of the edge to resist the pull of the roofing inwardly. Edge details may be selected from manufactur¬ ers who certify certain minimum performance to meet design requirements, based upon testing. Other designs may be used, provided they are tested and certified by an independent testing laboratory to meet the wind and pullout resis¬ tance design standards suggested in this docu¬ ment. 4.1 MEMBRANE ATTACHMENT The edge flashing may be the only restraint pre¬ venting a roof blow-off. In ballasted systems, ballast may be scoured away from the edge. Mechanically attached membranes may be at¬ tached only by the edge flashing at the building edge. The 100 Ib/ft (1 .46 kN/m) may not be suf¬ ficient if there is a large amount of scour, expos¬ ing a wide span of roofing. Consideration should be given to sealing the edge against air infiltration. Air infiltration may affect the loads on the roofing and the perim¬ eter edge detail 13 by adding a positive pressure under the roofing, thus compounding the effect of negative pressure above the roofing. cSee section 2.3 of the standard for the definition of corner regions. 14 Approved November 10, 1998 ANSI/SPRI ES-1-98 COMMENTARY 4.2 & 4.3 WIND RESISTANCE OF EDGE FLASHINGS & COPINGS Although all edge devices are to be tested ac¬ cording to the tests outlined in the Standard and its attachments, the following guidelines may be used to establish designs for testing. The guide¬ lines may be modified to achieve desired test results. Edge flashings, copings and the like should be secured with continuous cleats of 24 ga steel, 0.050 (2 mm) aluminum or metal of equivalent strength at the bottom of the face edge. Cleats should be secured with annular threaded or screw-shank nails long enough to penetrate the wood nailer at least 1-1/4″ (3 cm). Nail heads should be at least 3/16″ (5 mm) in diameter. Alternatively, cleats may be secured with mini¬ mum No. 8 (4 mm) screws long enough to pen¬ etrate the nailer 3/4″ (20 mm) or penetrate metal 3/8″ (10 mm). Where velocity pressures are less than 45 Ibs/ft2 (220 kg/m2), cleat fasteners should be placed no farther than 24* (600 mm) apart. Where velocity pressures are greater than 45 Ibs/ft2 (220 kg/m2) they should be spaced 16″ (400 mm) or closer. Fastener fre¬ quency should be doubled in corner regions. Nail heads should be larger than the narrowest dimension of the slotted holes. Where velocity pressures exceed 45 psf (220 kg/m2), add a screw through the back section of the edge flashing near the center of each section and at the center of the joint cover. Edge flashing sec¬ tions should be spaced to allow for expansion around this screw. Metal coping should be secured by a cleat at the wall exterior. Where velocity pressures exceed 45 psf (220 kg/m2), the coping should be se¬ cured on the inside with No. 10 (5 mm) galva¬ nized screw fasteners through neoprene wash¬ ers on 30″ (760 mm) or narrower centers. At higher velocity pressures, the centers should be 20″ (500 mm) or narrower. Screws should be long enough to penetrate the wood nailer at least 1 “ (25 mm). The effects of thermal expan¬ sion should be considered. Screw holes in the coping should be pre-punched or drilled oversize to allow for thermal expansion if aluminum thicker than .063″ (1 .6 mm) is used. To ensure adequate holding, edge designs should also include a drip edge that securely engages the cleat. Inadequate securement may lead to a release of the edge, resulting in the ultimate failure of the roof edge device. Fastener spacing is doubled in corner regions to account for the increased wind forces in these regions. 5 DESIGN PROVISIONS 5.1 WIND RESISTANCE TABLE 4 values have been calculated using Equation 6-1 from Section 6.5.1 of ASCE 7-951, for 1=1.0 and ^=1.0: cu = 0.00256 x Kz x Kzt x V2 x I in which: ch = Velocity Pressure (the Velocity Pres¬ sures shown in Table 4 of this Standard is actually “q/r as defined in ASCE 7- 95 and therefore are to be multiplied by “I” to obtain qz), Kz = Velocity Pressure Exposure Coefficient from Equation C-3 in the Commentary Section of ASCE 7-95 (Also shown as Table 6-3 in ASCE 7-95), = Topographical factor for buildings built on hills or escarpments (from Equation 6-2 of ASCE 7-95), V = Basic Wind Speed, mph, from Attach¬ ment I of this Standard and I = Importance factor defined in Table 3. Velocity Pressure “ch” is the pressure imparted by the energy of the wind. In practice, aerody¬ namics will cause actual wind pressures to dif¬ fer from theoretical values at certain locations on the building. A building with a flat, level (or slightly sloped) roof will experience greater forces at the corners and eaves than on interior roof surfaces because of eddy effects at the eaves. These effects are accounted for by us¬ ing the products of Pressure Coefficient and Gust Factor, GCP obtained from Table 5 (Sec¬ tion 5.1) which is taken from ASCE 7-951, Fig¬ ures 6-5 and 6-8, assuming an “effective wind area” of 10 square feet or less. The vertical component was taken from the values for Sur¬ face 2 on those Figures. ASCE-7-95 does not address the horizontal component of GCP at the roof edge. Therefore, the horizontal value of GCP was taken from the values for Surface 5, which is the vertical corner region. That surface 15 ANSI/SPRI ES-1-98 Approved November 10, 1998 was selected because it presents nearly the same geometry to the wind as would the roof edge. ASCE 7-95 suggests different pressure coeffi¬ cients in corner regions. Instead of using ASCE 7-95 pressure coefficients for corner regions in this Standard, the design method was simplified by requiring doubled fastening in these regions. 5.2 METAL THICKNESS Increased metal thickness improves the flatness reduces the “oil-can” effect of the roof edge metal. The required minimums do not address other important design factors such as fasten¬ ing pattern and frequency, continuous or inter¬ mittent cieating, stiffening ribs or brakes in the edges. Metal thickness may need to be in¬ creased for higher wind areas unless Tests RE- 2 or RE-3 have been performed. 5.3 GALVANIC COMPATIBILITY AND RESISTANCE Corrosion and strength should be considered in the choice of materials. This Standard focuses primarily on metal edge systems. When plastic materials are used, corrosion is not usually a factor (although environmental deterioration must be considered), however, strength of the materials must be considered. Corrosive potential can be roughly predicted by knowing the placement of the two metals in the Galvanic Series. The farther apart the metals are in the Galvanic Series, the greater is this potential for corrosion. Metals adjacent to each other in the Series have little potential for cor¬ rosion. In the following list (Galvanic Series), the metals high on the list are potentially corroded while those low on this list are protected. Fre¬ quently, the corrosion rate of “sacrificed” metals will be low, even if there is a potential for corro¬ sion. Thus there will generally be little corrosion between metals that are close to each other on the list, however, when they are in contact, the lower of a pair will be protected by the higher even if no perceptible corrosion is taking place. For this reason, steel, being lower on the list than zinc will be protected by the zinc, which is “sacrificed” to save the steel. Fortunately, though there is a potential for corrosion between zinc and steel, under most conditions, the rate of corrosion is minuscule so that the zinc lasts many years while electrolytically protecting the steel. Similarly, pairs of metals such as aluminum and zinc or aluminum and stainless steel will show no perceptible corrosion between them, because of their proximity to each other on the list. On the other hand, pairing copper with zinc or alu¬ minum or even steel must be avoided because copper is far from them on the Galvanic Series and the potential for corrosion is great. In extremely corrosive environments such as salt water environments, chemical plants or paper mills, corrosion resistant materials such as stain¬ less steel shall be used. Table 8 Galvanic Series14 Anodic or Least Noble (Corroded End) Magnesium Zinc Aluminum Cadmium Steel Stainless Steel Lead Tin Copper Titanium Silver Gold Cathodic or Most Noble (Protected End) TEST METHOD RE-1 The method with which the edge of the roofing membrane is terminated (edge flashing, nailer, or other) is the last anchor point to hold the membrane in place should the membrane hap¬ pen to separate from the roof deck during a high wind. When this happens, the roof system will put a load on the termination. Therefore, the termination must withstand a minimum force of 100 Ibs/ft (134 kg/m) when tested using the method. This value has been adopted from the ANSI RP-4 Standard. This is a new procedure. The precision and bias of the test measure has not been determined. 16 Approved November 10, 1998 ANSI/SPRI ES-1-98 TEST METHODS RE-2 and RE-3 4.2 Stabilization Stabilization is necessary during loading to in¬ sure that the specimen has reached equilibrium before considering a sustained load for a period of 60 seconds. As the specimen approaches its ultimate capacity, stabilization of the specimen will generally take longer to achieve. 4.3 Loading These test methods consist of applying loads on surfaces of a test specimen and observing de¬ formations and the nature of any failures of prin¬ cipal or critical elements of the coping or edge flashing system profiles or members of the an¬ chor systems. Loads are applied to simulate the static wind loading of the members. Test RE-2, for edge flashings, requires loads on only the vertical face since the uplift wind loading on a edge flashing member is considered to be neg¬ ligible. Since corners are difficult to test with these methods, corner areas are best handled by designing a device to pass RE-2 or RE-3 as appropriate and doubling the number of fasten¬ ers in corner regions. A recovery period between increases in incre¬ mental loading is allowed for the test specimen to attempt to assume its original shape prior to applying the next load level. The rate of loading can be a critical issue when specimens are subjected to continuously in¬ creasing load until failure is achieved. Loading rate has little meaning in RE-2 and RE-3 be¬ cause these methods employ incrementally in¬ creased loads sustained for relatively long times followed by brief recovery periods. This incre¬ mental method is more stringent than continu¬ ous loading because of the requirement of hold¬ ing a load for 60 seconds. The Standard requires full length specimens be¬ cause end conditions of discreet sections of copings and edge flashings can play a profound role in the failure mode of the materials. Fur¬ thermore, those products having noncontinuous cieating can exhibit different performance under testing than in the field if the cleats do not act upon the products as they would in the field. For example, if a product requiring two cleats in a 144 inch (5669 mm) length were tested as a 36″ (914 mm) sample with one cleat, the cleat would act over a larger percent of the product than would be experienced in the field, render¬ ing the results difficult to translate to the field. These are new procedures. The precision and bias of these test measures have not been de¬ termined. 4.4 Failure Some examples of “component failure that will not enable the edge flashing to perform as de¬ signed” would be: • Full nail pull-out at some point • Collapse of a cleat, fascia or cover • Disengagement of a face or coping at the drip-edge 5.2 Metal Thickness Table 6 was developed from NRCA and Factory Mutual recommendations. The table has been constructed to simplify its use over the Factory Mutual table and to extend the range of fascia widths beyond that given by NRCA. EXAMPLE Consider a 95 foot (30 m) high suburban confer¬ ence-type hotel building in Suburban Atlanta. At¬ tachment I is a map showing basic wind speeds for most of the United States. Basic Wind Speed from the Map is 90 mph. The “Exposure” for such a building according to the definitions given on Page 3 of the Design Standard is Exposure “C.” Consulting Table 4 for Exposure “C,” at 90 mph, the velocity pressure, qz, for a 95 foot structure at 90 mph is 26 pounds per square foot (psf). Velocity Pressure = 26 psf The Importance Factor (see Table 1 and Table 3) would be that of a Category II building (occupancy by more than 300 people in one room). The im¬ portance factor I, is 1.15 for this building. Importance Factor Multiplier (I) = 1.15 Velocity Pressure is multiplied by the Importance Factor Multiplier to obtain an Adjusted Velocity Pressure: Adjusted Velocity Pressure = 26 x 1.15 = 30 psf Using a Pressure Coefficient (GCp) from Table 5 of -2.3 for the vertical direction and -1 .8 horizontally, the following design force is calculated: Vertical Design Pressure: -2.3 x 30 Ib/sq. ft. = -69 Ib/sq. ft 17 ANSl/SPRI ES-1-98 Approved November 10, 1998 Horizontal Design Pressure: -1.8 X 30 Ib/sq. ft. = -54 Ib/sq. ft In this case, a coping must be tested to withstand 54 psf (Ib/sq. ft.) outward force and 69 psf uplift force. If the cooing had 4″ legs and a cap width of 18 inches, the cap would be required to withstand an upward force of: 1.5 sq. ft/ft x 69 Ib/sq. ft. = 104 Ib/ft and outward forces of: .33 sq. ft./ft x 54 Ib/sq. ft. = 18 Ib/ft on each face. The coping is to be tested according to SPRI Test RE-3 run on straight lengths. Doubling fasteners in the comer region will be sufficient instead of test¬ ing corner assemblies if the straight length assem¬ bly passes RE-3. Note that in testing the edge de¬ vice, upward forces and outward forces on a face are to be applied simultaneously and both face leg and back leg tests are to be run. If the perimeter were an edge flashing instead of a coping, it would need to withstand an outward de¬ sign force of 54 psf. If the edge flashing had a 6“ (0.5 sq. ft./ft) face, the design resistance would need to be 0.5 sq. ft ./ft x 54 Ib/sq. ft = 27 Ib/ft. The edge flashing is to be tested according to SPRI Test RE-2 run on straight lengths. Doubling fas¬ teners in the corner region will be sufficient instead of testing corner assemblies if the straight length assembly passes RE-2. Furthermore, the edge flashing must be tested according to SPRI Test RE- 1 to restrain a 45° pull of 100 pounds per foot if it is the termination of Single-Ply or Modified Bitumen Membrane. A roof edge may be designed and tested to meet the above criteria, or one may be selected that has been previously certified to meet the minimum de¬ sign requirements of this Standard. 18 Approved November 10, 1998 ANSl/SPRI ES-1-98 REFERENCES 1. Minimum Design Loads for Buildings and Other Structures, ASCE 7-95, American So¬ ciety of Civil Engineers, New York, 1996. 2. National Design Specifications for Wood Con¬ struction, NFPA, Washington, 1991. 3. Drilling and Anchoring Systems Design Manual, Rawlplug Company, Mississauga, ON. 4. Cold formed Steel Manual, AISI, 1986. 5. Adapted from NRCA Roofing and Waterproof¬ ing Manual, National Roofing Contractors As¬ sociation, Rosemont, IL, 1996, and Loss Pre¬ vention Data Sheet 1-49, Factory Mutual Re¬ search Corporation, Nonwood, MA. 1985. 6. Repair Manual for Low-Slope Roof Membrane Systems. ARMA/NRCA/SPRI, 1997. 7. James R. McDonald, Texas Tech University, Private communication with John Hickman, August, 1997. 8. National Design Specifications for Wood Con¬ struction, NFPA, Washington, 1991. 9. Drilling and Anchoring Systems Design Manual, Rawlplug Company, Mississauga, ON. 10. Cold formed Steel Manual, AISI, 1986. 11. Standard C15-96 Wood for Commercial-Resi¬ dential Construction, Preservative Treatment, American Wood-Preservers Association, Granbury, TX, 1996 12. Procedure for Evaluation of Corrosion Resis¬ tance of Steel Fasteners, SPRI, Needham MA, 1988. 13. A Guide to Achieve the Secured Single Ply, Technical Note No. 20, Dow Chemical Com¬ pany, Granville, Ohio, 1986. 14. Perry ed. Chemical Engineers Handbook, McGraw-Hill, New York, 1963. Table 23-1. An American National Standard implies a consensus of those substantially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether he has approved the stan¬ dard or not, from manufacturing, marketing, purchasing or using products, processes, or procedures not conforming to the standard. American National Standards are subject to periodic review and users are cautioned to obtain the latest edi¬ tions. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the American National Standards Institute. CAUTION NOTICE: This American National Standard may be revised or withdrawn at any time. The procedures of the American National Standards Institute require that action be taken to reaffirm, revise or withdraw this standard no later than five years from the date of approval. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute 19
