Hail Resistance of Roofing ProductsBuilding Research Division, U.S. Institute for Applied Technology, 1969 - 9 pages A test was developed for evaluating the hail resistance of roofings, in which synthetic hailstones (ice spheres) of various sizes were shot at roof assemblies at their free-fall terminal v * elocities.Indentations, granule loss and roofing fracture were observed.The principal conclusion is that:All roofing materials have some resistance to hail damage, but as the size of the hail increases, a level of impact energy is reached at which damage occurs.This level lies in the range of 1 1/2 to 2 inch (3.8-5.1 cm) hailstones for most prepared roofings.(Author). |
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Page 2
... layer of low - density ice . When an ice particle becomes too heavy to be raised farther by the updraft , it starts to fall . More condensation is collected during the fall , and once it reaches an area with temperatures above the ...
... layer of low - density ice . When an ice particle becomes too heavy to be raised farther by the updraft , it starts to fall . More condensation is collected during the fall , and once it reaches an area with temperatures above the ...
Page 3
... layer of clear , high - density ice . Sooner or later , the particle encounters an- other strong updraft , starts ... layers of milky ( low density ) ice and clear ( high density ) ice . When the hailstone encounters no updraft suf ...
... layer of clear , high - density ice . Sooner or later , the particle encounters an- other strong updraft , starts ... layers of milky ( low density ) ice and clear ( high density ) ice . When the hailstone encounters no updraft suf ...
Page 4
... layer of silicone grease . The hailstones were cast in these molds in two stages , in order to permit expansion of water during freezing to occur without shat- tering the hailstones . Water was poured into the mold through the opening ...
... layer of silicone grease . The hailstones were cast in these molds in two stages , in order to permit expansion of water during freezing to occur without shat- tering the hailstones . Water was poured into the mold through the opening ...
Page 6
... layer of felt makes the shingle slightly more vulnerable . The improved performance usually involved only 14 - in ( 0.6 cm ) larger hailstones , but this represented re- sistance to 6.3 or 9.5 more foot pounds ( 8.5 or 12.8 joules ) of ...
... layer of felt makes the shingle slightly more vulnerable . The improved performance usually involved only 14 - in ( 0.6 cm ) larger hailstones , but this represented re- sistance to 6.3 or 9.5 more foot pounds ( 8.5 or 12.8 joules ) of ...
Page 7
... layers of bitumen and reinforcing membranes . Some of these roofs are surfaced with a smooth layer of bitumen and others are surfaced with a layer of pebbles , crushed stone or light weight aggregate particles in addition to a layer of ...
... layers of bitumen and reinforcing membranes . Some of these roofs are surfaced with a smooth layer of bitumen and others are surfaced with a layer of pebbles , crushed stone or light weight aggregate particles in addition to a layer of ...
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15 cents air gun apparatus Applied Technology areas of different Asbestos cement asphalt flood coat Asphalt Roofing asphalt shingles automatic data processing building damage Building Research Building Science Series Built-up roofs Bureau of Standards Cement and Concrete Center Class C shingle Coal tar Concrete Properties cracking cylinder dense decks dents DEPARTMENT OF COMMERCE diameter different vulnerability felt damage Fiberboard on 1-in Foamboard free-fall terminal velocity freezing ft 61 cm Gas cylinder Glass fiber insulation hail damage hail resistance hailstone carrier Hailstone Molds Hailstorms ice spheres indentation Institute for Applied interply asphalt Interrelations Between Cement Joules kg/m² kg/m³ large hailstones launcher lb/sq Meteorol microswitches National Bureau Nonbituminous Roofing organic felt polyethylene Portland Cement prepared roofings reported Resistance of Roofing resistant to hail shingles showed Sidney H sizes of hailstones slag solidly supported areas specimen steel decking substrates tested Type 235 shingles U.S. DEPARTMENT U.S. Government Printing velocity 9 ст