47.5 MB - The Whole Building Design Guide

Figure 4-27:Metal roof covering peeledaway at a St. Stanislauscampus buildingFor buildings located in flood hazard areas, especially areas notsubject to storm surge, elevation well above the predicted floodlevel is the most effective damage-reduction measure. Dry floodproofingmay be used to provide some degree of protection,although if floodwaters rise higher than the designed level ofprotection, the damage can be catastrophic. This technique, generallyfeasible for flood depths of only 2 or 3 feet, is expensiveand difficult to implement on existing buildings. Depending onthe expected depth of water, local soil properties, and the sizeand location of openings, the facilities can be designed to limitwater infiltration through the walls, openings, and conduits, andprevent envelope failure due to excessive hydrostatic pressure.Dry floodproofed buildings must have detailed emergency plans,with clear instructions for deployment of devices and other measures.Lack of periodic maintenance can render floodproofingmeasures ineffective.Another alternative for minimizing structural damage to existingbuildings is to provide wet floodproofing. This approach, which isnot allowed for new construction, allows water to flood the lowerfloors protected with water-resistant materials and finishes thatcan be easily cleaned and restored.4-38 OBSERVATIONS ON THE PERFORMANCE OF CRITICAL FACILITIES