huangyhg

roofing hail damage
does anyone know of any good sources for info on hail damage to roofing systems? additionally, is anyone ever heard of the haige engineering standards, and do they have a web site?
need to know what kind of roof system. hail damage is different for different systems. for shingles, most significant impact (forgive the pun) is loss of granule surfacing, resulting in premature aging. insurance companies don't like to pay anything for this because it is difficult to prove. i usually look for indicative damage that shows the severity and quantity of hail impact such as dings on flashings, windows, sheet metal, etc. from this you may conclude a relative level of damage to roof surfacing. for concrete tile roofs, damage to surface coating is likely, but can be readily seen. for clay tile, cracking and sudden movement from temperature drop are most common problems. same for concrete tile.
for built-up, modified bitumen, or single ply systems the damage will depend upon the type of surfacing (if any) and the type of membrane. as an example, a gravel surfaced built-up roof is not significantly affected by the initial hail impact, but as the hail accumulates, the asphalt approaches a freezing temperature which then allows fracture by subsequent impact if large enough. difficult to spot and characterize though. thermal impact can be significant to any membrane system. surface temperature can go from 150f to 40f in a matter of minutes, impacting the structure and the membrane.
an excellent paper on this subject is "hail damage to roofing: assessment and classification", by william c. cullen, national roofing contractors association (nrca).
the paper summarizes many sources of hail testing data and proposes kinetic energy as a means of quantifying hail resistance. the required impact energy to cause material indentation, surface fracture, and puncture is presented for asphalt shingles and built-up roofing (bur).

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