FLOOD02274

• County: Statewide
• Basin: Statewide
• Title: Hurricane Opal in Florida A Building Performance Assessment
• Date: 8/30/1996
• Prepared For: Florida
• Prepared By: FEMA
• Floodplain - Doc Type: Floodplain Report/Masterplan

foundations, one- to three-story concrete block structures, and one- to three-story wood-frame
structures founded on timber piles. Many of these structures were behind concrete sheetpile
seawalls. Typical post-FIRM structures in the study area are one-, two-, and three-story wood-frame
structures elevated on timber or concrete pile foundations. Post-FIRM structures, although
sustaining damage, performed much better than the pre-FIRM structures.

FLOOD DAMAGE AND VULNERABLE COMPONENTS

Because most of the structural damage observed by the BPAT along the Gulf of Mexico
shoreline appeared to have been caused by flood forces rather than wind forces, the team focused
on flood-induced damage. The observations of the team presented in this report address
following issues:

. storm-induced erosion and scour

. debris flow and impact

. slab foundations

. pile and pier foundations

. framing systems

. connections

. bracing

. breakaway construction and enclosures below elevated buildings

. stairs, decks, and porches

. utilities

. seawalls

. drainage and drainage structures

Other issues discussed in this report include (1) the incorporation of pre-FIRM construction
into new construction during the improvement of existing structures and (2) structures that
appear to have been built without the aid of detailed plans prepared by a design professional. The
BPAT found that poor workmanship frequently accompanied the lack of professional design in
such instances.

RECOMMENDATIONS

The BPAT developed recommendations that address observed damages and vulnerabilities
for both new construction and substantial improvements to existing structures in areas subject to
coastal and hurricane storm forces. These recommendations include the following:

. Restudies and FIRM revisions now underway for the affected communities will use updated
V-Zone mapping procedures and may result in more extensive areas being shown as V-
Zones. Consequently, until such time as revised FIRMs are completed, the affected
communities should consider studying local coastal flooding conditions that occurred
during Hurricane Opal to determine whether areas shown as coastal A-Zones on the
current FIRMs, as well as areas within several hundred feet of the Gulf of Mexico shoreline,
are actually subject to V-Zone flood forces. If such areas are identified, the affected

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EXECUTIVE SUMMARY