0 Copyright 1993 by I-lxtg Engineering Co. Ail rights reserve& This material may not be reproduced or utilized in any form or by any 111ems, electronic or Inecllanicd, including photocopying, recording, or by any inf-i,rmation storage and retrieval systenl, without prior written permission from Haag Engineering Co., 2455 McIver Lane, Carrollton, Tcxas 75006.
Haag Engineering Co. is one of the oldest firms in this country specializing in the analysis of failure and damage. Mechanical, civil, structural, chernical, electrical, aerospace, architectural, and meteorological specialties are reprcscnted 011 the Hag engineering staff. Services include determining cause and/or scope of damage, computii1g costs of repair, reconstruction monitoring, reworkkstoration analysis, laboratory and fjeld testing, and legal testimony. Offices are located in Dallas and Houston. Hag Engineering Co. serves a broad spectrum of clients ranging from large and small companies and corporations throughout the world to major insurance and adjusting companies, law firms and attorneys, and individuals. Haag Engineering research data and studies have resulted in the publication and dissemination of information vita'r to persons ia?volvd in dzrrrage assessment, including a 20-year study of hail damage to cedar shingles. Other studies have been conducttxl on hail damage to various types of manufactured roofing materials... - 11 -
Scott J. Morrison, P.E. M.S. Civil Engineering B. S. Civil Engineering B.A. Architecture Scott J. Morrison graduated from Iowa State University with a B.A. in Architecture and a B.S. in Civil Engineering. He also received a N.S. in Civil Engineering (Structures) from the University of Oklahoma. Currently, he is a rnennber of the American Society of Civil Engineering, American Institute of Steel Construction, Axnerican Concrete Institute, Wind Engineering Research Council, and Chi Jipsilon, the rnational civil engineering scholastic honorary. Mr. Morrison has inspected and assessed hail- and wind-caused damage to hundreds of roofs. He participated in writing Wood Roofs: Damage and Repair, Second and Third Editions. His speaking experience includes numerous lectures on steel structures, steel connection design, steel and concrete fastening design, rcsidential and corrmcrcial roof darnage assessment, and damage to strictures.... - 111 -
I. HAIL A. 2-3 3-4 4-5 5f Figure I. 1 - Average Hail Days in United States (Source: Wcathenvise) k -1-
A frozen water droplet, piece of dust, insect, etc., is caught in an updraft and carried upward. 2. Cycling A layer of ice is added each time the hailstone is carried upward and downward through the thunderstorm cloud. This cycling continues until the stone is ti;o hi-,?vy to Ire supported by updraft winds, and it falls to asth. -8.- N -2-
Figure 11. I - Directionality of Hail -3-
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XI. IIAIL-CAUSICD DAMAGE (CONT'D.) D. Functionul damge to roofing 1. Diminishment of water-shedding capability 2. l<eduction in the expected long-term service life -5-
5 1f2" 314" 1" 1'~l~SIiOw) SEE FOR DAMAGE TO ROW, ROOFING AND DETERIORATED COMPOSITION LS'HIAJGl,ES, ESPECIALLY WfIERE UNSUPPORIED. Painted wood surfacw and deteriorated gray-black slates (especially at comers) chippcd; most altrnrinurr~ vwts, flashings, valleys, and siding dented. TXI&S OLD SIZE FOR DAMAGE TO K4OST LIGH11WEIGHT COMPOSIl7ON SHlNC;I,ES. 'illin and/or deteriorated wood shingles and shakes occasionally punctured or cracked. Deteriorated unba1l;istd built-up roofs bruised, and brittle flood coats cracked. Singlc pane wiuclows and thin skylight shells cracked or broken. 1-1/4' 1-112" 1-314" 2" 6. 'I'able 11.2 - Wail Sizc Versus Typical Damage -6-
1. Appurtenances 2. Hail-sensitive roofing areas D. Select up to four. test areas 1. Outline onc-square areas on direction-facing slopes 2. Visually observe punctures and tears; hand manipulate for bruises 4. Assess ridge and valley shingles separately -7-
- 7 A. Beginrzirzg in 1963 1. Target specific shingle area 2. Verify ice sphere weight 3. Measure ice sphere velocity 4. Calculate impact energy 5. Document impact site 6. De-asphalt shingle in vapor degreaser 7. inspect mats for darnagp (fracture, tear, CT strain over area greater than f /4-inch diameter) 0. A detailed protocci is appended as.4thchment A. 1. Hag studies 2. Proprietary threshold studies 3. Proprietary development studies -c -8-
2. Shingles producul by the same mallufacturer and of similar warranty but with organic versus fiberglass mats have demonstrated approximately the same hail threshold rcsistancc. 3. With composition shingles produced by the same manufacturer, products have not exhibited increased hailstone damage threshold sizes with increased warranty c/up~!.ions. 4. Of all cornpositiorl shingles tested, a nlodified bitumen product has demonstrated the greatest impact resistance as a function of weight. B. ASTM E 822-81: Starulurd Fructice for Uetemining Resistance of Solar Collector Covers to Huil by Impact with Propelled Ice Balls G. Urderwriters Luhorulory (under development) -9-
HAIL AND COMPOSITION SI;IINGI,ES ATTACHMENT A - 10 -
'Test panels would bc constructed to sirnulate typical roofing applications and set in a heated oven (14OoF) and kept there until the shiigles had "cooked down" and tab adhesives, bonded, approximately 48 hours. Mylar sheets would be cut to panel ditncnsions, fitted over the roofing, and marked with roofing outlines. Roofing on each panel would be imp~~cted with nlolded ice spheres propelled at no less than free-fall speeds. Projectile speeds and projectile weights would be measured, and impact energies, calculatd. Impact energies would fall within the range betwecn minus zero and plus ten perccrlt of target impact energies, or the data would be discarded. The projcctilcs would be launched perpendicular to the panels. Areas of roofing, nlatcria?s avot~ltl be targeted according to support conditiorls (unsupported, rnarginally supported, and fully supported) or geometry (field, edge, corner, upper trough, lowcr trough, etc.). Immediately after a simulated hailstone would strike a rooring xrlaterial surface, the impact area would be rnarketl. Marks latcr would be tr-ansfcrrcd to the ~nylar sheet overlays to form a ycrmment mmd. Mcwiing materids carchiiy wouk! be scrutinized for impactcaused damage. Cornposition shingle tabs would bc cut from the panels, deasphalted in a vapor-degreasing unit, anti cxamincd for damage. Damage results also would bc recorded on ihc mylar sheets. Tlrunag': to the roofing material Wouici be delcintxi as diminishment of the wat.cr-shdding capability or the reduction of expected long-tcrxn service life of the tested materials. More specifically, for composition shingles, impact-cawxi damage would be the rupture of the shingle's structural clernent, its mat (base), or strain (permanent deformation) of thebaseover an area greater tharl U4 inchindiameter. The various stages of the tcstirg procedure also would be documented photographically.... - 11 -