47.5 MB - The Whole Building Design Guide

Figure 4-43:Lifted batten covers onThird District Fire Stationmetal roofAlthough the estimated wind speed in Bay St. Louis was slightlylower than the design wind speed, the wind blew off most of theroof membrane from the Hancock County EOC, located in thecity (see Figure 4-44). The damage was initiated with the separationof metal edge flashing that had an uncleated vertical face. Inaddition to roof damage, the hardware on the exterior door failedand the door blew inward. As a result of rainwater penetration andflooding, most of the interior was ruined. Although most of thefacility operations were moved before hurricane landfall, the remainingbuilding occupants had to be evacuated during the event.Jackson County EOC in Pascagoula experienced similar damageto its roofing when the metal edge flashing peeled off and liftedportions of the roof membrane. However, the roof damage didnot cause water damage, because the cast-in-place reinforced concreteroof deck was capable of resisting rainwater penetration.The building’s reinforced concrete walls and roof deck resistedthe wind loads very well. The walls and roof deck were also extremelyresistant to wind-borne debris, as was the exterior glazingretrofitted with shutters that protected the openings.The edge flashing on low-slope roofs that usually initiatesthe peeling of roof membranes can be easily retrofitted withadditional screws, to prevent it from uplifting and causing a progressivefailure of the roofing system.OBSERVATIONS ON THE PERFORMANCE OF CRITICAL FACILITIES4-59