|
Report by: PSI Environmental Geotechnical Construction
Date: October 16, 1997
Our Report Number: 198-56050-2
Remarks: A Technician from Professional Service Industries, Inc. (PSI) was present at the referenced project to witness the impact testing for the FallGuard Skylight Hail Protection Screens.
The system consisted of a FallGuard Skylight Screen covered by a steel wire mesh with 1" by 1" grid wire, 0.063 inches in diameter. The wire mesh is used for hail protection.
The system was tested by dropping two pound weights through a 3" ID PVC pipe for a vertical distance of 13.604 ft. A total of 4 weights were dropped.
The hail protection screen was inspected after each weight was dropped. No damage was observed. The welds were not broken and the wire was not visibly damaged.
Hail Damage
Hail damage to roof coverings, flashings, skylights, air conditioning units, duct work, sheet metal enclosures, etc. is significant. During the ten-year period 1975 through 1984, there were 785 Factory Mutual System losses totaling $37.9 million in property damage and business interruption.
Hail Protectors
When outdoor equipment has not been designed to resist hail impact per table 1, or does not have sufficient inherent strength to resist severe hailstorms, hail screens or guards may be placed over the equipment. This is particularly applicable to skylights. The protector may be deflected by impact; however; the energy of the stones will be considerably dissipated.
New outdoor equipment such as skylights, etc. should be designed to resist, without permanent deformation, the impact energy of a 2 inch diameter hail stone (see table 1). Due to unfavorable loss experience, skylights deserve special attention.
|
|
